After three half-lives, 1/8 or 0.125 of the initial quantity of strontium-90 remains, indicating that 87.5% has decayed.
To calculate the fraction of strontium-90 that remains after three half-lives, we need to understand the concept of half-life. The half-life of a radioactive substance is the time it takes for half of the initial quantity to decay.
The half-life of strontium-90 is about 29 years. After one half-life (29 years), half of the strontium-90 would have decayed, leaving only half remaining.
After two half-lives (58 years), half of the remaining strontium-90 would decay again, leaving one-fourth (half of half) of the original amount. Similarly, after three half-lives (87 years), half of the remaining strontium-90 would decay, leaving only one-eighth (half of one-fourth) of the initial quantity.
Therefore, after three half-lives, the fraction of strontium-90 remaining would be 1/8, which can also be expressed as 0.125 or 12.5%.
It's important to note that the rate of decay remains constant regardless of the initial quantity, so after each subsequent half-life, the fraction remaining will be halved again.
Learn more about Strontium-90
brainly.com/question/31391222
#SPJ11
Covalent bonds do not play an important role in protein
structure, why?
A. Only one amino acid, cysteine, can fo covalent bonds in
protein structure
B. Covalent bonds are highly susceptible to hydro
The correct answer is option A: Only one amino acid, cysteine, can form covalent bonds in protein structure.
Covalent bonds do play a vital role in protein structure. A covalent bond is a bond that is formed by sharing electrons between two atoms, and it is very strong.
Amino acids, which are the building blocks of proteins, are held together by covalent bonds in a linear chain. The covalent bonds between amino acids are known as peptide bonds.The only amino acid that can form covalent bonds in protein structure is cysteine. It is a sulfur-containing amino acid that forms a disulfide bond.
Cysteine residues can form disulfide bonds with one another, which contribute to the three-dimensional structure of proteins.The primary structure, secondary structure, tertiary structure, and quaternary structure of proteins are all defined by the covalent bonds that hold the amino acid chains together.
Consequently, covalent bonds play a crucial role in the structure and function of proteins.
Thus, the correct answer is option A.
To learn more about proteins :
https://brainly.com/question/10058019
#SPJ11
specifically blocks the release of ach from axon terminals at the injection site
Botulinum toxin specifically blocks the release of ACh from axon terminals at the injection site. Option B is correct.
This is a kind of protein toxin produced by the bacterium Clostridium botulinum. This toxin blocks the release of acetylcholine, a neurotransmitter, from the axon terminals at the injection site, thereby paralyzing the target muscle(s) and causing flaccid paralysis.
Curare is a drug that blocks the receptor sites for acetylcholine on the motor end plate. Tetrodotoxin is a potent neurotoxin that binds to fast voltage-gated sodium channels, inhibiting the flow of sodium ions into cells and resulting in the prevention of action potential initiation and propagation.
Cocaine interferes with the reuptake of dopamine, serotonin, and norepinephrine, increasing the synaptic concentrations of these neurotransmitters and resulting in the characteristic “high” associated with the drug.In the case of botulinum toxin, it blocks the release of ACh from axon terminals at the injection site.
ACh is a neurotransmitter that plays a critical role in muscle contraction, and when its release is blocked, the muscle(s) affected by the toxin are unable to contract, leading to flaccid paralysis. The given question is a part of the topic neuromuscular junction and action potential.
Therefore, Option B is correct.
Learn more about Botulinum -
brainly.com/question/28538555
#SPJ11
A tank contains 6 liters of water in which is dissolved 24 grams of chemical. A solution containing 1 g/L of the chemical flows into the tank at a rate of 4 L/min, and the well-stirred mixture flows out at a rate of 3 L/min. Let x(t) be the amount of the chemical in the tank after t minutes since the solution containing the chemical begins to flow into the tank.
How long will it take to reduce the chemical concentration in the tank to 2 g/L?
It will take 8 minutes to reduce the chemical concentration in the tank to 2 g/L.
Let x(t) be the amount of the chemical in the tank after t minutes since the solution containing the chemical begins to flow into the tank.
There are 6 liters of water in which 24 grams of chemical is dissolved. So, the concentration of the chemical in the tank is `24/6 = 4 g/L`.
Let t be the time in minutes it takes to reduce the concentration of the chemical to 2 g/L.
During the time interval from 0 to t minutes, the amount of chemical in the tank decreases from 4t grams to 2t grams.
The change in the amount of chemical in the tank is:
`x'(t) = - 4t/6 + 1 x 4/60`
Simplifying gives:
`x'(t) = -2t/15 + 1/15`
Now, let's solve for t such that
x(t) = 2 g/L.
Since x'(t) is the rate of change of x(t), we have:
`x'(t) = (dx)/(dt)``dx/dt
= -2t/15 + 1/15``2x/15 - x/15
= t``t = x/15`
We want to find the time t it takes to reduce the chemical concentration in the tank to 2 g/L.
The concentration of the chemical in the tank is 4 g/L initially, so the amount of chemical to be removed is:
`24 - 2 * 6 = 12`
The rate of removal of the chemical is 3 L/min, so it will take:`12/(3 * 2) = 2 minutes`
to remove all the chemical.
Therefore, the time it will take to reduce the chemical concentration in the tank to 2 g/L is:
`t = x/15 = 2/15 x 60 = 8 minutes`
Learn more about time interval from the given link:
https://brainly.com/question/28238258
#SPJ11
For a particular reaction, the standard entropy change is 531
J/K and the standard enthalpy change is 322 kJ. At what temperature
will this reaction become spontaneous?
The spontaneity of a chemical reaction is determined by the change in Gibbs free energy, which is determined by the equation ΔG = ΔH - TΔS. If ΔG is negative, the reaction is spontaneous, while if ΔG is positive, the reaction is non-spontaneous.
The equation can also be written as ΔG = ΔG° + RTlnQ, where ΔG° is the standard free energy change, R is the gas constant, T is the temperature, and Q is the reaction quotient. If ΔG° is negative, the reaction is spontaneous under standard conditions (1 atm pressure and 298 K).
If the standard entropy change is positive, it means that the disorder or randomness of the system is increasing. This is a favorable condition for spontaneity since spontaneous processes tend to lead to greater disorder. Therefore, if the standard entropy change for a reaction is positive, it increases the likelihood that the reaction will be spontaneous.
However, the sign of the standard enthalpy change (ΔH°) must also be considered, as it can either increase or decrease the spontaneity of the reaction. If ΔH° is negative (exothermic reaction), it will increase the spontaneity of the reaction, while if ΔH° is positive (endothermic reaction), it will decrease the spontaneity of the reaction. Therefore, both the signs of ΔH° and ΔS° must be considered when determining the spontaneity of a reaction.
If the standard entropy change (ΔS°) is 531, it indicates that the disorder of the system is increasing, which favors spontaneity. However, the sign of ΔH° is not given, so it cannot be determined whether the reaction is spontaneous or non-spontaneous based on this information alone. Further information is needed to determine the spontaneity of the reaction.
To know more about Gibbs free energy, here
https://brainly.com/question/13795204
#SPJ11
3. (25 pts.) As an extension of \# 2 , consider tropolone ( 1 below). Tropolone is a compound that can act as an acid by donating a proton ({H}^{+}) via attack by generic b
Tropolone is an organic compound with a molecular formula of C7H5O. This compound can act as an acid by donating a proton, {H}+ via attack by a generic base. Tropolone can act as a weak acid due to the presence of a hydroxyl group.
It has a chemical structure in which a cycloheptatrienone ring is substituted with a hydroxyl group in the 2 position, as well as a keto group in the 4 position. Tropolone is a colorless to yellow solid that is used in the synthesis of other organic compounds. Tropolone is capable of forming coordination complexes with many metal ions, including aluminum, iron, and cobalt.
These complexes are stabilized by the presence of the hydroxyl and keto groups on tropolone, which can act as electron donors to the metal ion. Tropolone is a versatile ligand that is used in coordination chemistry and as a metal ion chelator. Additionally, tropolone has antibacterial and antifungal properties, making it a useful compound in the development of new pharmaceuticals. In conclusion, tropolone is a fascinating organic compound that can act as an acid by donating a proton and is used in a wide range of applications.
To know more about cycloheptatrienone visit:
https://brainly.com/question/33320240
#SPJ11
1. Which of the following structures is nod consistent with rules for drawing Lewis structures? (AIl nonbonding lome pairs of electrons and atoms are drawn ar intended.)
In the following Brønsted-Lo
To represent nitrous acid (HNO2) using its Lewis structure, we can follow certain rules:
1. Determine the total number of valence electrons in the molecule. Nitrous acid consists of one hydrogen atom (H), one nitrogen atom (N), and two oxygen atoms (O). The total number of valence electrons is calculated as follows: 5 (N) + 2(6) (O) + 1 (H) = 14.
2. Connect the atoms with single bonds.
3. Arrange the remaining electrons in pairs around the atoms to satisfy the octet rule (or the duet rule for hydrogen). In this case, we need to place the remaining 12 electrons in six pairs around the three atoms: N, H, and O.
4. Count the number of electrons used in bonding and subtract it from the total number of valence electrons to determine the number of non-bonding electrons or lone pairs.
5. Check the formal charge of each atom. In the Lewis structure of nitrous acid, the formal charges are: N = 0, O1 = -1, O2 = 0, and H = +1.
To know more about electrons visit:
https://brainly.com/question/15885173
#SPJ11
numbers of isomers in the Alkane family
The number of isomers in the alkane family depends on the number of carbon atoms present in the molecule. Alkanes are hydrocarbons with only single bonds between carbon atoms, and they follow the general formula CnH2n+2, where n represents the number of carbon atoms.
For a given number of carbon atoms, the number of isomers increases exponentially. Here are the number of isomers for different numbers of carbon atoms:
1. Methane (CH4): Only one possible structure. No isomers.
2. Ethane (C2H6): Again, only one possible structure. No isomers.
3. Propane (C3H8): There are two possible structures: a straight-chain structure and a branched structure. These are isomers.
4. Butane (C4H10): There are two isomers: two straight-chain structures and one branched structure.
5. Pentane (C5H12): There are three isomers: three straight-chain structures and two branched structures.
6. Hexane (C6H14): There are five isomers: five straight-chain structures and three branched structures.
7. Heptane (C7H16): There are nine isomers: nine straight-chain structures and five branched structures.
As the number of carbon atoms increases, the number of possible isomers increases dramatically. The exact number of isomers for a given alkane can be determined using principles of organic chemistry and structural isomerism. The branching of the carbon chain can lead to different arrangements and configurations, resulting in multiple isomers.
It is important to note that the number of isomers mentioned above represents the structural isomers, where the carbon chain arrangements differ. However, there can also be other types of isomers, such as stereoisomers, for compounds with more complex structures.
The number of isomers continues to increase with larger alkane molecules, making it impractical to list all the possible isomers for higher members of the alkane family. However, the general trend is that as the number of carbon atoms increases, the number of isomers also increases exponentially.
for more questions on alkane family
https://brainly.com/question/32392756
#SPJ8
A chemist must dilute 82.5mL of 521.mM aqueous aluminum chloride
AlCl3 solution until the concentration falls to 103.mM . He'll do
this by adding distilled water to the solution until it reaches a
cer
Chemists often have to dilute concentrated solutions to specific concentrations using distilled water. This procedure is useful to create standardized solutions and to decrease the reactivity of strong reagents.
A chemist has to dilute 82.5 mL of a 521.0 mM aqueous aluminum chloride (AlCl3) solution until the concentration falls to 103.0 mM by adding distilled water to the solution until it reaches a certain volume.SolutionThe number of moles of AlCl3 initially in 82.5 mL of 521.0 mM solution is calculated using the formula below:
The formula for the final volume can be written as follows:Final volume = Amount of solute / Final concentrationAmount of solute = 0.0429 molesFinal concentration = 0.1030 moles/LFinal volume = (0.0429 mol) / (0.1030 mol/L) = 0.416 L (or 416 mL)The final volume is obtained by adding a certain amount of water to 82.5 mL of the 521.0 mM AlCl3 solution. The amount of water required to obtain a total volume of 416 mL is: Volume of water required = Total volume - Initial Volume of water required = 0.416 L - 0.0825 L = 0.3335 L (or 333.5 mL)
Therefore, a chemist must add 333.5 mL of distilled water to 82.5 mL of 521.0 mM AlCl3 solution to get a 103.0 mM solution.
To know more about strong reagents visit:
brainly.com/question/31147542
#SPJ11
(1) The total heat capacity of a Bomb-type calorimeter, C, can be obtained from a sample with a known value of reaction heat. Assume that 0.500 g of benzoic acid (C 3
H 3
COOH .
molar mass is 122.12 g/mol ) completely burns in a steel bomb (with oxygen) of a bomb calorimeter containing 1209 g of water. The temperature of the system increases from 296.35 K to 298.59 K. It is known that the reaction heat effect of complete combustion of benzoic acid under these conditions is −3226KJ/mol. The specific heat capacity of water is 4.184 J/g/K. Try to calculate the heat capacity of the Bomb-type calorimeter.
The heat capacity of the Bomb-type calorimeter is approximately -5897 J/K. To calculate the heat capacity of the Bomb-type calorimeter (C), we can use the equation:
Q = C * ΔT
where Q is the heat absorbed or released by the system, C is the heat capacity, and ΔT is the change in temperature.
In this case, the heat absorbed by the system (Q) can be obtained from the reaction heat of combustion of benzoic acid. The reaction heat effect of complete combustion of benzoic acid is -3226 kJ/mol.
First, we need to calculate the number of moles of benzoic acid used:
Number of moles = Mass / Molar mass
Number of moles = 0.500 g / 122.12 g/mol
Number of moles ≈ 0.004098 mol
Next, we need to calculate the heat absorbed by the system (Q):
Q = -3226 kJ/mol * 0.004098 mol
Q ≈ -13.220 kJ
Since 1 kJ = 1000 J, we convert the heat absorbed to joules:
Q = -13.220 kJ * 1000 J/kJ
Q ≈ -13,220 J
Now, we can calculate the change in temperature (ΔT):
ΔT = Final temperature - Initial temperature
ΔT = 298.59 K - 296.35 K
ΔT ≈ 2.24 K
Finally, we can calculate the heat capacity of the Bomb-type calorimeter (C):
C = Q / ΔT
C = -13,220 J / 2.24 K
C ≈ -5897 J/K
Therefore, the heat capacity of the Bomb-type calorimeter is approximately -5897 J/K.
To know more about heat visit :
https://brainly.com/question/13860901
#SPJ11
Given the equalities below, how many unicorns (or parts of unicorns) can Jen get if she has 336.4 bags of glitter? 1 kitty cat =3.00 flufy bunnies 6.50 bags of glitter = 1 fluffy bunny 0.145 unicorns =1 kitty cat
According to the information we can infer that Jen can get approximately 2.501 unicorns (or parts of unicorns) if she has 336.4 bags of glitter.
How many unicorns can Jen get if she has 336.4 bags of glitter?To solve this problem, we need to use the given equalities as conversion factors and perform the necessary calculations. Here are the steps:
Convert bags of glitter to fluffy bunnies using the conversion factor:
336.4 bags of glitter * (1 fluffy bunny / 6.50 bags of glitter) = 51.754 fluffy bunniesConvert fluffy bunnies to kitty cats using the conversion factor:
51.754 fluffy bunnies * (1 kitty cat / 3.00 fluffy bunnies) = 17.251 kitty catsConvert kitty cats to unicorns using the conversion factor:
17.251 kitty cats * (0.145 unicorns / 1 kitty cat) = 2.501 unicornsAccording to the above we can conclude that Jen can get approximately 2.501 unicorns (or parts of unicorns) if she has 336.4 bags of glitter.
Learn more about conversion factors in: https://brainly.com/question/6988886
#SPJ4
rank the following in order of decreasing δ and energy of light absorbed. a: [cr(en)3]3 b: [cr(cn)6]3− c: [crcl6]3−
The order of decreasing δ and energy of light absorbed for the compounds [Cr(en)3]3+, [CrCl6]3-, and [Cr(CN)6]3- is as follows: [Cr(en)3]3+ > [CrCl6]3- > [Cr(CN)6]3-.
In the given order, [Cr(en)3]3+ has the highest value of δ and absorbs light with the highest energy. This can be attributed to the presence of the ethylenediamine ligands (en), which are strong field ligands. The strong field ligands cause a larger splitting of the d-orbitals in the central chromium ion, resulting in a higher energy gap between the ground state and excited states. Therefore, [Cr(en)3]3+ exhibits a higher δ and absorbs light with higher energy.
On the other hand, [Cr(CN)6]3- has the lowest value of δ and absorbs light with the lowest energy. This is because cyanide ligands (CN) are weak field ligands, leading to a smaller splitting of the d-orbitals and a lower energy gap. As a result, [Cr(CN)6]3- has the lowest δ and absorbs light with lower energy compared to the other two compounds.
In between these, [CrCl6]3- falls in the middle with intermediate values of δ and energy of light absorbed. Chloride ligands (Cl) are moderately strong field ligands, causing a moderate splitting of the d-orbitals and an intermediate energy gap.
In summary, the order of the compounds with decreasing δ and energy of light absorbed is [Cr(en)3]3+ > [CrCl6]3- > [Cr(CN)6]3-. This order is determined by the strength of the ligands and the resulting splitting of the d-orbitals, which influences the energy gap and the energy of light absorbed by the compounds.
cyanide https://brainly.com/question/13246521
#SPJ11
if
you could explain the answer, thank you!
1. Draw all the important resonance structures for the following ion showing all lone pairs of electrons, foal charges and double bonds. Show the electron flow by using arrows for full credit. (6 po
The given ion is not mentioned in the question; therefore, I am unable to provide the exact resonance structures for that ion. However, I can provide you with an example of how to draw resonance structures for an ion and illustrate the electron flow using arrows. Let's consider the nitrate ion (NO3-). Resonance structures are drawn to explain the delocalization of electrons and the stability of ions.
Resonance structures are formed by shifting electron pairs from double bonds and lone pairs to form new multiple bonds and achieve octet configurations. Below are the resonance structures for the nitrate ion, along with the electron flow indicated by arrows:
Resonance structures for the nitrate ion (NO3-):
- Electron flow by using arrows:
In the above resonance structures, each oxygen atom is equivalent, and there is no double bond character in the molecule. All the atoms in these structures have full octet configurations, and the formal charge on each oxygen atom is -1. The arrows represent the movement of electron pairs. A double-headed arrow is used to indicate the movement. In the first structure, the double bond between one of the oxygen atoms and the nitrogen atom breaks, and the two electrons move towards the nitrogen atom. In the second structure, the lone pair on the nitrogen atom moves to form a double bond between nitrogen and one of the oxygen atoms. In the third structure, the double bond between another oxygen atom and the nitrogen atom breaks, and the two electrons move towards the nitrogen atom. These resonance structures illustrate the delocalization of electrons and the stability of the nitrate ion.
To know more about electrons visit:
https://brainly.com/question/12001116
#SPJ11
2.13. Explain how the results of the gold-foil experiment led Rutherford to dismiss the plum-pudding model of the atom and create his own model based on a nucleus surrounded by electrons.
According to the information we can infer that the results of the gold-foil experiment led Rutherford to dismiss the plum-pudding model of the atom and propose his own model with a nucleus surrounded by electrons.
How the results of the gold-foil experiment led Rutherford to dismiss the plum-pudding model of the atom and create a new model?The gold-foil experiment conducted by Rutherford involved firing alpha particles at a thin sheet of gold foil. The results showed that most alpha particles passed through the foil with only a small fraction being deflected or bouncing back.
This observation was inconsistent with the prevailing plum-pudding model of the atom. Rutherford concluded that there must be a tiny, dense, positively charged region within the atom, which he called the nucleus.
Also, he proposed a new model of the atom where the nucleus is surrounded by orbiting electrons. This led to the development of the nuclear model of the atom, replacing the plum-pudding model.
Learn more about Rutherford in: https://brainly.com/question/33646524
#SPJ4
An aqueous solution is 22.0% by mass
ethanol,
CH3CH2OH, and has a density
of 0.966 g/mL.
The molality of ethanol in the solution is
The molality of ethanol in the aqueous solution is 0.399 mol/kg.
the molality of ethanol in the solution, we need to calculate the amount of ethanol in moles and divide it by the mass of water in kilograms.
Mass percent of ethanol = 22.0%
Density of the solution = 0.966 g/mL
We need to determine the mass of ethanol and water in the solution.
Assuming we have 100 grams of the solution, the mass of ethanol would be 22.0 grams (since it is 22.0% by mass).
The mass of water can be calculated by subtracting the mass of ethanol from the total mass of the solution:
Mass of water = Total mass of solution - Mass of ethanol
Mass of water = 100 g - 22.0 g
Mass of water = 78.0 g
We convert the mass of ethanol and water to moles.
Molar mass of ethanol (CH3CH2OH) = 46.07 g/mol
Number of moles of ethanol = Mass of ethanol / Molar mass of ethanol
Number of moles of ethanol = 22.0 g / 46.07 g/mol
We need to calculate the molality.
Molality (m) = Number of moles of solute / Mass of solvent in kg
Mass of solvent in kg = Mass of water / 1000 (since 1 kg = 1000 g)
Substituting the values:
Molality = (22.0 g / 46.07 g/mol) / (78.0 g / 1000)
Molality ≈ 0.399 mol/kg
Therefore, the molality of ethanol in the aqueous solution is 0.399 mol/kg.
To know more about molality refer here
https://brainly.com/question/30640726#
#SPJ11
which of the following changes would result in an increase in the entropy of the system? select all that apply.
A crystal of sodium chloride is heated from 275K to 290K, an ice cube melts at 273K and a tire is punctured, releasing the gas trapped inside would result in an increase in the entropy of the system. All the options are correct.
The following changes would result in an increase in the entropy of the system:
An ice cube melts at 273KWhen ice cubes are subjected to heat, they melt and convert into liquid water. This process of melting increases the disorder of the ice cubes, and therefore, the entropy of the system increases. A tire is punctured, releasing the gas trapped inside.
When the tire is punctured, the pressure inside the tire drops, and the gas trapped inside the tire escapes into the surroundings. This process increases the disorder of the gas molecules and therefore, the entropy of the system increases. A crystal of sodium chloride is heated from 275K to 290K When a crystal of sodium chloride is heated, the disorder of the atoms/molecules in the crystal increases, but the order of the crystal structure remains the same.
Therefore, All the options are correct.
Learn more about entropy -
brainly.com/question/419265
#SPJ11
A
is scientific knowledge established through direct observation and remains constant. Scientific knowledge can change when scientists
.
Answer:
Explanation:Scientific knowledge is knowledge in, or in connection with, any of the sciences or technology, that is accumulated by systematic study and organized by general principles. Scientific knowledge refers to a generalized body of laws and theories to explain a phenomenon or behavior of interest that are acquired using the scientific method⁴. Laws are observed patterns of phenomena or behaviors, while theories are systematic explanations of the underlying phenomenon or behavior.
Scientific knowledge is not established through direct observation alone, nor does it remain constant. Scientific knowledge can change when scientists discover new evidence, test existing hypotheses, revise existing theories, or develop new methods or technologies. Science is a dynamic and ongoing process that seeks to understand the physical world and its phenomena in a rigorous and objective way.
5.7 In table format, list two uses for sulphuric acid and two uses for calcium oxychloride. (4 ma
Sulphuric acid is a colorless and odorless liquid. Its chemical formula is H2SO4. It is commonly used in many industries due to its reactivity and acidic nature.
Here are two common uses for sulphuric acid: Manufacture of fertilizers: Sulphonic acid is used to produce fertilizers such as ammonium sulphate, superphosphate of lime, and ammonium phosphates. These fertilizers help increase crop yield and improve soil fertility. Industrial cleaning agent: Sulphonic acid is used to clean metals and other materials in many industries. It is also used to clean iron and steel before they are coated or painted .Calcium oxychloride is a white powder. Its chemical formula is Ca(ClO)2.
To know more about chemical formula visit:
brainly.com/question/18441768
#SPJ11
Briefly explain (a) why there may be significant scatter in the fracture strength for some given ceramic material, and (b) why fracture strength increases with decreasing specimen size. 240 The tensile strength of brittle materials may be deteined using a variation of Equation 8.1. Compute the critical crack tip radius for an Al 2
O 3
specimen that experiences tensile fracture at an applied stress of 275MPa (40,000 psi). Assume a critical surface crack length of 2×10 −3
mm and a theoretical fracture strength of E/10, where E is the modulus of elasticity.
The critical crack tip radius for an Al2O3 specimen that experiences tensile fracture at an applied stress of 275MPa (40,000 psi) is approximately 0.27 mm.
There may be significant scatter in the fracture strength for some given ceramic material due to the following reasons:
Homogeneity: Ceramic materials are often heterogeneous, and the structure of materials is not uniform. So, stress concentration and crack growth differ from region to region. Surface condition: The strength of a material is highly dependent on the surface condition. Surface flaws such as pores, scratches, or roughness may produce local stress concentrations that cause the material to fail at lower loads.
Defects: Cracks, pores, and other defects are common in ceramics. Defects in materials weaken their strength. Fracture toughness: Ceramics are brittle materials and have low fracture toughness. Due to this property, they fail quickly and catastrophically when subjected to external loads.
b) The following are the reasons why fracture strength increases with decreasing specimen size:Due to specimen size, the effect of the surface flaws is reduced. As the sample size decreases, the total surface area of the sample also decreases. There is less chance of a major defect on the surface that can initiate the fracture process. Smaller specimens have a smaller volume that can dissipate the energy of fracture.
As the specimen size decreases, the volume decreases, and the strain energy that is released during fracture is distributed over a smaller volume. Therefore, the energy per unit volume increases, causing an increase in fracture strength. Here's how to compute the critical crack tip radius for an Al 2O3 specimen that experiences tensile fracture at an applied stress of 275MPa (40,000 psi):
Given data:Surface crack length, a = 2 x 10-3 mm.
Theoretical fracture strength,
[tex]\alpha _f[/tex] = E/10
= E/10
= 4000 MPa (given that E is the modulus of elasticity)
Applied stress, σ = 275 MPa (40,000 psi), Critical crack tip radius, [tex]r_c[/tex] =?.
According to the Griffith theory, the tensile stress required to propagate a crack is given
byσ = [tex](2E *[/tex] [tex]y_(crack)_(tip)[/tex])) / [tex](\pi * r_c)[/tex] ... [1] where [tex]y_(crack)_(tip)[/tex]) is the surface energy per unit area.
At criticality, the stress required to propagate a crack is equal to the theoretical fracture strength.
Therefore, [tex]\alpha _f[/tex] = σ = [tex](2E[/tex] [tex]*[/tex] [tex]y_(crack)_(tip)[/tex]) /[tex](\pi * r_c)[/tex]... [2]
Rearrange Equation [2] to solve for [tex]r_c[/tex].= [tex](2E *[/tex] [tex]y_(crack)_(tip)[/tex]) / [tex](\pi * \alpha _f)[/tex]
Substitute E = 400 GPa, [tex]y_(crack)_(tip)[/tex][tex]= 2100 J/m2[/tex]
= 2.1 × 10-6 J/mm2, and [tex]\alpha_f[/tex]= 4000 MPa.
[tex]r_c[/tex] = ([tex]2 * 400 * 103 MPa * 2.1 * 10-6 J/mm2[/tex]) /[tex](\pi * 4000 MPa)[/tex]
≈ 0.27 mm:
The critical crack tip radius for an Al2O3 specimen that experiences tensile fracture at an applied stress of 275MPa (40,000 psi) is approximately 0.27 mm.
To know more about Fracture strength visit-
brainly.com/question/29557147
#SPJ11
a solution is made by dissolving 4.50 g of nacl in enough water to make 70.0 ml of solution. what is the concentration of sodium chloride in units of weight/volume percent?
To calculate the weight/volume percent concentration of sodium chloride in the solution, we need to determine the mass of sodium chloride and the volume of the solution.
Given to us is:
Mass of sodium chloride (NaCl) = 4.50 g
Volume of solution = 70.0 ml
First, we need to convert the volume of the solution from milliliters to liters:
Volume of solution = 70.0 ml = 70.0 ml × (1 L / 1000 ml)
Volume of solution = 0.070 L
Next, we can calculate the weight/volume percent concentration using the formula:
Weight/volume percent = (Mass of solute / Volume of solution) × 100
Plugging in the values:
Weight/volume percent = (4.50 g / 0.070 L) × 100
Weight/volume percent = 64.29%
Therefore, the concentration of sodium chloride in units of weight/volume percent is approximately 64.29%.
Learn more about concentration here:
https://brainly.com/question/10720472
#SPJ 4
Two reactions and their equilibrium constants are given.
A+2B2C↽−−⇀2C↽−−⇀DK1K2=2.15=0.130A+2B↽−−⇀2CK1=2.152C↽−−⇀DK2=0.130
Calculate the value of the equilibrium constant for the reaction D↽−−⇀A+2B.
The value of the equilibrium constant (K) for the reaction D ↽−−⇀ A + 2B can be calculated using the given equilibrium constants (K1 and K2) for the reactions A + 2B2C and 2C ↽−−⇀ D, respectively.
The equilibrium constant for a reaction can be determined by multiplying the equilibrium constants of individual steps if the reactions are combined. Therefore, the equilibrium constant for the reaction D ↽−−⇀ A + 2B can be calculated as K = (K1 * K2).
Given equilibrium constants:
K1 = 2.15
K2 = 0.130
To find the equilibrium constant for the reaction D ↽−−⇀ A + 2B, we multiply the equilibrium constants of the individual reactions involved.
K = K1 * K2
K = 2.15 * 0.130
K = 0.2795
Hence, the equilibrium constant (K) for the reaction D ↽−−⇀ A + 2B is 0.2795. This value represents the ratio of the concentrations of the products (A and 2B) to the concentration of the reactant (D) at equilibrium.
Learn more about equilibrium constant
https://brainly.com/question/31321186
#SPJ11
the calcite in limestone will dissolve slowly over time in the presence of slightly acid water. this reaction creates:\
The reaction of calcite in limestone slowly dissolving over time in the presence of slightly acid water creates calcium ions [tex](Ca_2^+)[/tex] and bicarbonate ions [tex](HCO_3^-)[/tex].
Calcite is a mineral that is the primary component of limestone. When limestone comes into contact with slightly acid water, such as water containing carbon dioxide [tex](CO_2)[/tex] or weak acids, it undergoes a chemical reaction known as dissolution. In this reaction, the calcite in limestone reacts with the acid to form soluble calcium ions [tex](Ca_2^+)[/tex] and bicarbonate ions [tex](HCO_3^-)[/tex]. The dissolution of calcite leads to the gradual breakdown or erosion of the limestone structure over time.
This process is an example of chemical weathering, where the interaction between water and minerals in rocks results in their gradual breakdown and alteration. The release of calcium and bicarbonate ions into the water can have implications for the composition of the water and its potential to contribute to the formation of features such as caves or sinkholes in limestone-rich areas.
To know more about chemical weathering
brainly.com/question/29616569
#SPJ11
If you had added 1.5 mL of methanol (M.W. 32.0, d0.791 g/mL ) to a 25 mL round-bottom flask, how many millimoles of methanol would you have used? Enter your answer using no decimal places (45). Include the correct areviation for the appropriate unit Answer: If you had added 1.5 mL of methanol (M.W. 32.0, d0.791 g/mL ) to a 25 mL round-bottom flask, how many millimoles of methanol would you have used? Enter your answer using no decimal places (45). Include the correct areviation for the appropriate unit Answer:
The number of millimoles of methanol used by adding 1.5 mL of methanol (M.W. 32.0, d0.791 g/mL) to a 25 mL round-bottom flask is 37.08 mmol.
To calculate the number of millimoles of methanol used, we need to use the given information about the volume (1.5 mL), molar mass (32.0 g/mol), and density (0.791 g/mL) of methanol.
First, we calculate the mass of methanol added to the flask using the density and volume: mass = volume × density = 1.5 mL × 0.791 g/mL = 1.1865 g.
Next, we convert the mass to moles using the molar mass of methanol: moles = mass / molar mass = 1.1865 g / 32.0 g/mol = 0.03708 mol.
Finally, we convert moles to millimoles by multiplying by 1000: millimoles = moles × 1000 = 0.03708 mol × 1000 = 37.08 mmol.
learn more about Molar mass here:
https://brainly.com/question/22997914
#SPJ11
If a reaction starts woith 0.480 mol Mg, how many moles of silver are produced?
Answer:
The reaction you are referring to is:
Mg + 2AgNO3 → Mg(NO3)2 + 2Ag
0.960 moles of silver will be produced
Explanation:
The balanced equation shows that 1 mole of Mg reacts with 2 moles of AgNO3 to produce 2 moles of Ag.
If we start with 0.480 moles of Mg, then we will produce 0.480 * 2 / 1 = 0.960 moles of Ag.
Here is the calculation:
Number of moles of Ag produced = (Number of moles of Mg) * (Moles of Ag produced per mole of Mg)
= 0.480 moles * 2 moles/mole
= 0.960 moles
Therefore, 0.960 moles of silver will be produced if the reaction starts with 0.480 moles of Mg.
Solvolysis of bromomethylcyclopentane in methanol gives a complex product mixture of the following five compounds. Propose mechanisms to account for these products.
Solvolysis is the process of reacting an organic compound with a solvent, especially one that has a high dielectric constant.
When bromomethyl cyclopentane undergoes solvolysis in methanol, a complex product mixture of the following five compounds is obtained. Here's a proposed mechanism to account for these products:
Firstly, the bromine atom present in bromomethyl cyclopentane gets replaced by a methanol molecule. As a result, a carbocation is formed in the first step.
Step 1: Bromomethyl cyclopentane + Methanol → Carbocation + Hydrogen bromide
Step 2: the carbocation undergoes attack by a methanol molecule. This attack can occur in two different positions, leading to two different products.
Step 2a: Carbocation + Methanol → Compound 1
Step 2b: Carbocation + Methanol → Compound 2
Step 3: the carbocation is attacked by a molecule of methanol to form an intermediate. The intermediate then undergoes a shift of the C-C bond, resulting in two more compounds.
Step 3a: Carbocation + Methanol → Intermediate → Compound 3
Step 3b: Carbocation + Methanol → Intermediate → Compound 4
Finally, the intermediate undergoes another methanol molecule attack, leading to the formation of the final product.
Step 4: Intermediate + Methanol → Compound 5T
Therefore, this is the mechanism proposed to account for the five products obtained from the solvolysis of bromomethyl cyclopentane in methanol.
Learn more about solvolysis:
https://brainly.com/question/29555642
#SPJ11
Name two safety precautions you will take while perfoing this lab. A metal sample weighing 38.30 g and at a temperature of 100.0 ∘
C was placed in 50.22 g of water in a calorimeter at 23.3 ∘
C. Once at equilibrium, the temperature of the water and the metal was 29.6 ∘
C. 2. What was the ΔT for the water? △T=TG−Ti 3. What was the ΔT for the metal? (can be a negative number!) 4. Knowing that the specific heat of water is 4.18 J/g ∘
C, calculate how much heat, q, flowed into the water? q=( sp. heat ) * mass * ΔT 5. Knowing how much heat flowed into the water from the metal, calculate the specific heat of the metal. (Remember, qwater = - qmetal!)
The specific heat of the metal is -0.493 J/g ∘C. Two safety precautions that one should take while performing this lab is as follows: One should use gloves while working with the metal sample that has been heated.
This is to ensure that there is no direct contact between the skin and the heated metal sample. One should keep a safe distance while heating the metal sample. This is to avoid any kind of accidental injury in case the metal sample is heated to a very high temperature.
To calculate the heat that flowed into the water, the following formula is used:q=( sp. heat ) × mass × ΔTsp.
heat of water = 4.18 J/g ∘Cmass of water (m) = 50.22 gΔT = 6.3 ∘Cq = (4.18) × (50.22) × (6.3) = 1322.84 JThus, the heat that flowed into the water is 1322.84 J.
To calculate the specific heat of the metal, the following formula is used:qwater = - qmetalqmetal = - qwaterqmetal = -(1322.84 J)qmetal = - (-1322.84 J)qmetal = 1322.84 Jsp.
heat of metal = qmetal / (mass × ΔT)mass of metal (m) = 38.30 gΔT = -70.4 ∘Csp. heat of metal = 1322.84 J / (38.30 g × (-70.4) ∘C) = -0.493 J/g ∘C
Thus, the specific heat of the metal is -0.493 J/g ∘C.
Learn more about mass of metal Here.
https://brainly.com/question/28730262
#SPJ11
g the solubility product constant for sodium fluoride is > 1. if sodium fluoride is dissolved in water you can say that the equilibrium concentrations of sodium and fluoride ions are:
When sodium fluoride is dissolved in water, the equilibrium concentrations of sodium and fluoride ions are relatively high due to the solubility product constant being greater than 1.
The solubility product constant (Ksp) is a measure of the extent to which a solid substance dissolves in water to form ions. For sodium fluoride (NaF), the Ksp is greater than 1.
When sodium fluoride is dissolved in water, it dissociates into sodium (Na+) ions and fluoride (F-) ions. The equilibrium concentrations of these ions depend on the solubility product constant and the initial concentration of the sodium fluoride.
Since the Ksp for sodium fluoride is greater than 1, it indicates that the equilibrium concentrations of the sodium and fluoride ions are relatively high. This means that a significant amount of sodium fluoride dissolves in water and forms a large concentration of sodium and fluoride ions.
To give you an example, let's say you have a solution of sodium fluoride with an initial concentration of 0.1 M. After it dissolves, the equilibrium concentrations of sodium and fluoride ions might be 0.08 M and 0.08 M, respectively. These concentrations would reflect the fact that a significant amount of sodium fluoride has dissociated into its ions.
You can learn more about solubility products at: brainly.com/question/1419865
#SPJ11
, Describe how ozone is formed naturally in the stratosphere?
5, Explain why ozone levels fluctuate seasonally in the stratosphere?
6, Identify the types of compounds that are most responsible for the thinning of the stratospheric ozone layer?
Ozone is formed naturally in the stratosphere due to the photodissociation of oxygen. The photodissociation of oxygen molecules that occurs when they absorb high-energy ultraviolet radiation, specifically radiation with a wavelength between 240 and 310 nanometers (nm), causes the formation of ozone.
However, ozone levels fluctuate seasonally in the stratosphere due to the changes in temperature, wind patterns, and the amount of sunlight that enters the atmosphere. During the winter season in polar regions, the stratosphere experiences extreme cold temperatures that cause polar stratospheric clouds to form. These clouds lead to the formation of chlorine and bromine compounds that can destroy ozone. As a result, the ozone layer thins, and there is a seasonal hole in the ozone layer over Antarctica,
which is more than 100 times larger than the average size of the United States. Thinning of the stratospheric ozone layer is primarily due to the release of human-made compounds called halocarbons, including chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and other halogenated compounds. These compounds break down and release chlorine and bromine, which can destroy ozone.
To know more about radiation visit:
https://brainly.com/question/31106159
#SPJ11
When tydrogen sulfide gas is tuled into a Part A solution of sodium hydroxide, the reaction fos sodium sulfide and water. How mary grams of sodium sultide are foed +150 g of hydogan sudtide is bishiod into a stilenn containing 200 g of sodam trydroxide, assuming that the soourn sult ide is made in 92.6% yied?
So, 318 grams of sodium sulfide are produced by reacting 150 grams of hydrogen sulfide with 200 grams of sodium hydroxide, assuming a 92.6% yield.
The balanced equation of the given chemical reaction is as follows: [tex]H2S(g) + 2NaOH(aq) → Na2S(aq) + 2H2O(l)[/tex]. The molar mass of [tex]NaHS[/tex] is 56 g/mol (23 + 1 + 32).
One can use the molar mass of [tex]NaHS[/tex] to calculate the moles of [tex]H2S[/tex] by using the following formula:moles of [tex]H2S[/tex] = mass of [tex]H2S[/tex] / molar mass of [tex]H2S[/tex]= 150 g / 34 g/mol= 4.41 moles of H2S. Now, the balanced equation shows that for every 1 mole of [tex]H2S[/tex] reacted, we get 1 mole of [tex]Na2S[/tex] .
So we can safely say that there are 4.41 moles of [tex]Na2S[/tex] produced. Since 92.6% yield is obtained, we need to multiply this value by 0.926, which results in the actual amount of [tex]Na2S[/tex] produced.4.41 × 0.926 = 4.08 moles of [tex]Na2S[/tex] . The molar mass of [tex]Na2S[/tex] is 78 g/mol (2 x 23 + 32).
One can use the molar mass of [tex]Na2S[/tex] to calculate the mass of Na2S by using the following formula:mass of [tex]Na2S[/tex] = moles of [tex]Na2S[/tex] × molar mass of [tex]Na2S= 4.08 × 78= 318 g[/tex]. So, 318 grams of sodium sulfide are produced by reacting 150 grams of hydrogen sulfide with 200 grams of sodium hydroxide, assuming a 92.6% yield.
To know more about chemical reaction here
https://brainly.com/question/22817140
#SPJ11
design synthetic ,using retrosynthetic.
provide all conditions
any other commercially available precursors that contain only {C}, {H} and {O}
To design a synthetic route using retrosynthesis, we need to start by identifying the target molecule and breaking it down into simpler precursors. In this case, the target molecule is not specified, so I cannot provide a specific synthetic route. However, I can explain the concept of retrosynthesis and how it is used.
Retrosynthesis is a technique used in organic chemistry to plan the synthesis of complex molecules by working backwards from the target compound to simpler starting materials. It involves breaking down the target molecule into smaller fragments or precursors, which can then be obtained through known reactions or commercially available compounds.
When designing a synthetic route using retrosynthesis, you need to consider the following steps:
1. Identify the target molecule: Determine the structure of the molecule you want to synthesize.
2. Break it down: Mentally break the target molecule into smaller fragments or precursors. These fragments should ideally contain only carbon (C), hydrogen (H), and oxygen (O) atoms, as mentioned in your question.
3. Identify known reactions: Identify known reactions that can be used to assemble the precursor fragments. This requires knowledge of various functional group transformations and reaction mechanisms.
4. Plan the synthesis: Once you have identified the precursors and known reactions, plan the synthesis by working backwards from the target molecule to the starting materials. This involves connecting the precursors in a logical sequence using the known reactions.
5. Consider conditions: When designing the synthetic route, consider the reaction conditions required for each step. This includes factors such as temperature, pressure, solvent, and catalysts. The specific conditions will depend on the reaction being used.
6. Consider commercially available precursors: Check if any of the precursors required for the synthesis are commercially available. If so, it can simplify the synthesis by eliminating the need to prepare those precursors from scratch.
#SPJ11
functional groups of the reactant and product. https://brainly.com/question/30598839
The individual markings on the metric side of your ruler are blank apart. When measuring the length of the object is placed as close as possible to blank. The other end of the object will be somewhat between two of the markings, which allows one to measure the length to the nearest blank of a blank.
