The given question is incomplete, the complete question is:
Suppose the amount of a certain radioactive substance in a sample decays from 1.30 mg to 100. ug over a period of 29.5 days. Calculate the half life of the substance Round your answer to 2 significant digits.
Answer:
The correct answer is 7.974 days.
Explanation:
Based on the given question, the concentration of a radioactive substance present in a sample get decays to 100 micro grams from 1.30 milligrams in 29.5 days. There is a need to find the half-life of the substance.
Radioactive decay is an illustration of first order reaction.
K = (2.303 / t) log [a/(a-x)]
Here a is 1.30 mg and (a-x) is 100 micrograms = 100 * 10^-3 mg or 0.1 mg, and t is 29.5 days. Now putting the values we get,
K = (2.303 /29.5)log (1.30/0.1)
= 2.303/29.5 log13
= 2.303/29.5 * 1.1139
K = 0.0869
The half-life or t1/2 is calculated by using the formula, 0.693 / K
= 0.693 / 0.0869
= 7.974 days.
What is the probability that an offspring will have a
heterozygous genotype? |
Answer:
25,50,25
Explanation:
Describe why some acids are strong while other acids are weak
Answer:
I hope this help you. Mark me as brainliest and rate pleaseExplanation:
the terms strong and weak as applied to acids. As a part of this it defines and explains what is meant by pH, Ka and pKa.
It is important that you don't confuse the words strong and weak with the terms concentrated and dilute.
As you will see below, the strength of an acid is related to the proportion of it which has reacted with water to produce ions. The concentration tells you about how much of the original acid is dissolved in the solution.
It is perfectly possible to have a concentrated solution of a weak acid, or a dilute solution of a strong acid.
Which statement BEST describes how a golf club does "work" on a golf ball?
(A) When the club hits the ball the club transfers all of its kinetic energy to the ball.
(B) All of the kinetic energy from the club is transferred to the ball as they both move through the air.
(C)
Some of the kinetic energy from the golf club is transferred to the ball and some transforms into sound
and heat, but the total energy remains the same.
(D) The golf club loses kinetic energy when it hits the ball and the ball gains kinetic energy from the air as it
travels
Answer:
C
Explanation:
It looks pretty reasonable to me
What mass of salt would you need to add to 1.00kg of water to achieve a freezing point of -5 degrees C
Answer:
The type of salt to be added to the water is not known from the question but no worries, I will try to give you the step by step procedure to answer any type of question similar to this.
To answer this question, we should know some facts.
1. the molar freezing point depression constant of water (Kf) = 1.86 K kg/mol
2. the molar mass of the salt if NaCl = 58.5 g/mol ; KCl = 74.5 g/mol
3. since the salt can dissociate if NaCl or KCl into two ions, the Van't Hoff factor ( i )= 2
Note that: the change in freezing point, molarity, deepression constant and van't Hoff factor are related by this formula;
ΔTf = i Kf m
So lets take NaCl as the salt:
Molar mass = 58.5 g/mol
Van't Hoff factor = 2
1. calculate the number of moles
So we can calculate the molarity of the salt NaCl from the formula;
m = ΔTf / i Kf
m = 5 / 2 * 1.86
m = 5 / 3.72
m = 1.344 mol/kg
2. calculate the number of moles of the salt required
Next is to multiply the molarity by the mass of water. Density of water = 1kg/L
number of moles = 1.344 mol/kg * 1 Kg/L * 1 kg water
number of moles = 1.344 moles.
3. calculate the mass of the salt.
numner of moles = mass / molar mass
mass = number of moles * molar mass
mass = 1.344 * 58.5
mass = 78.624 g of NaCl salt.
You can follow these steps to solve for the type of salt you are given in the question.
Consider the following reaction where Kc = 2.90×10-2 at 1150 K: 2 SO3 (g) 2 SO2 (g) + O2 (g) A reaction mixture was found to contain 4.71×10-2 moles of SO3 (g), 5.00×10-2 moles of SO2 (g), and 4.53×10-2 moles of O2 (g), in a 1.00 liter container.
Answer:
The reaction is not in equilibrium and must move in a backward manner i.e towards the reactant so that it will attain equilibrium
Explanation:
The complete question is as follows;
Consider the following reaction where Kc = 2.90×10-2 at 1150 K: 2 SO3 (g) 2 SO2 (g) + O2 (g) A reaction mixture was found to contain 4.71×10-2 moles of SO3 (g), 5.00×10-2 moles of SO2 (g), and 4.53×10-2 moles of O2 (g), in a 1.00 liter container.
Is the reaction at equilibrium? If not, what direction must it run in order to reach equilibrium? The reaction quotient, Qc, equals . The reaction A. must run in the forward direction to reach equilibrium. B. must run in the reverse direction to reach equilibrium. C. is at equilibrium.
Solution
The first thing to do here is to calculate the pressure of each of the gases. This would be useful in the equilibrium calculations. We calculate this by dividing the respective number of moles by the volume of the container.
Now, since the volume of the container is 1L, then the number of moles will be equal to the pressure of the gaseous substances, although units will be different.
So, [SO3] = 4.71 * 10^-2 mol/L
[SO2] = 5.00 * 10^-2 mol/L
[O2] = 4.53 * 10^-2 mol/L
The equation of the reaction is as follows;
[tex]2SO_{3(g)}[/tex] ⇆ [tex]2SO_{2(g)}[/tex] + [tex]O_{2(g)}[/tex]
We proceed to calculate the reaction quotient Qc
Mathematically Qc for this reaction = [[tex]SO_{2}[/tex]]^2 × [[tex]O_{2}[/tex]]/ [[tex]SO_{3}[/tex]]^2
Qc = {(5 * 10^-2)^2 * (4.53 * 10^-2)}/ (4.71 * 10^-2)^2 = 5.11 × 10^-2 mol/L
Now, we are given that the value of Kc = 2.9 * 10^-2 which is less than Qc
Since Kc < Qc, the backward reaction is favored.
Now to the question;
The reaction is not in equilibrium and must move in a backward manner i.e towards the reactant so that it will attain equilibrium
Hcl and 1-isopropylcyclohexane formation
Answer:
Spahgetti
Explanation:
Give the full electron configuration for sulfur.
electron configuration:
Answer:
[Ne] 3s² 3p⁴
Electrons per shell: 2,8,6
Answer : 2,8,6 (Sulphur Atom)
2,8,8 (Sulphur Ion)
Wax melts when it is heated which most likely describes what is true of the result of this reaction
Answer:
Was is a hydrocarbon therefore when heated some co2 escapes but later solidifies
Explanation:
Hope it helps
Which of the following are not created by an arrangement of electric charges
or a current (the flow of electric charges)?
A. An electric field
B. A magnetic field
C. A quantum field
D. A gravitational field
Answer:
gravitational and quantum ARE NOT, but electric and magnetic ARE. there is a similar question to this but it's the exact opposite, so don't get confused
Select the correct answer. What is heat of vaporization?
A. It is the heat required to change a substances temperature by 1C
B. It is the heat required to change a gram of substance from a solid to a liquid
C. It is the heat required to change a substance from a solid directly to a gas
D. It is the heat required to change a gram of substance from a liquid to a gas
E. It is the heat required to separate one substance into two substances
Answer:
D) it is the heat required to change a gram of substance from a liquid to a gas
Explanation:
idk i think its correct but if its wrong just let me know
An attempt at synthesizing a certain optically active compound resulted in a mixture of its enantiomers. The mixture had an observed specific rotation of 14.1°. If it is known that the specific rotation of the R enantiomer is –28.4°, determine the percentage of each isomer in the mixture. g
Answer:
The percentage of the R-enantiomer is 26.18% while the percentage of the S-enantiomer is 73.82%
Explanation:
If the specific rotation of R enantiomer = -28.4, then the specific rotation of S = +28.4
Now, let us have x = % R, thus
% S = 100-x =y
Hence;
{- 28.4x + 28.4( 100 -x)}/100= 14.1
Thus;
-28.4x + 2840 -28.4x = 1410
-56.8x + 2840 = 1410
-56.8x = 1410-2840
-56.8x = -1430
x = 1430/56.8
x = 26.18%
y = 100-26.18% = 73.82%
Which correctly lists the three processes that are affected by freeze and thaw cycles?
creep, landslide, and deposition
deposition, creep, and weathering
landslide, slump, and deposition
O slump. weathering, and creep
Answer:
slump. weathering, and creep
Explanation:
Freezing and thawing cycle in geology is the process in which water gets in between soil space or rock cracks, freeze in a cold season, and then melt in a warmer season, exerting a force on the soil or rock around it. This force is due to the expansion and contraction of water when it changes from ice to liquid water.
The three geological processes slump, weathering and creep all depend on thawing and freezing cycle among other factors.
Slump: Slump is a type of geological process that occurs when coherent mass of loosely consolidated materials or a rock layer moves a short distance down a slope. The movement of a slump is characterized by sliding along a concave-upward or planar surface. Causes includes earthquake shocks, thorough wetting, freezing and thawing, undercutting, and loading of a slope.Weathering: This is a geological process that results in the gradual disintegration of rocks into smaller sizes. It is one of the most important soil formation process, and is different from erosion by the degree of movement of the soil formed. Weathering does not move the soil from its origin. Thawing and freezing cycle plays a major role in weathering by helping crack up the rocks and by also tearing the rock apart. plays a major role.Creep: This is the slow, often imperceptible downslope movement of soil or other debris. The effects of creep is often seen in the presence of physical characteristics like bent trees, tilted fences, and cracked walls. Creep is caused by multiple factors, of which heaving is likely the most important process. Heaving involves the expansion and contraction of rock fragments, and occurs during cycles of wetting and drying, as well as freezing and thawing.Answer:
It is slump, weathering and creep
Explanation:
Took the test on edg
A gas occupies a volume of 180 mL at 35 °C and 95.9 kPa. What is the volume of the gas at conditions of STP?
Answer:
the volume of the gas at conditions of STP = 151.04998 ml
Explanation:
Data given:
V1 = 180 ml
T1 = 35°C or 273.15 + 35 = 308.15 K
P1 = 95.9 KPa
V2 =?
We know that at STP
P2 = 1 atm or 101.3 KPa
T2 = 273.15 K
At STP the pressure is 1 atm and the temperature is 273.15 K
applying Gas Law:
[tex]\frac{P_1V_1}{T_1} =\frac{P_2V_2}{T_2}[/tex]
putting the values in the equation of Gas Law:
[tex]V_2=\frac{P_1V_1T_2}{T_1P_2}[/tex]
V_2 =[tex]\frac{95.9\times180\times273.15}{308.15\times101.3}[/tex]
V2 = 151.04998
therefore, V2 = 151.04998 ml
Answer:
151 mL is the correct answer to the given question .
Explanation:
We know that
[tex]PV =n RT[/tex]
Where P =pressure ,V=volume and T=Temperature
Given
P=95.9 kPa.
V=[tex]180 * 10 ^{-3}[/tex]
R=25/3
T=273 + 35 =308k
Putting these value into the equation we get
[tex]95.9\ * 180\ *\ 10^{-3} \ =\ n * \frac{25}{3} * 308[/tex]
n=[tex]6.72 * 10^{-3}[/tex]
Now using the equation
[tex]n= \ \frac{V}{22.4}[/tex]
[tex]6.72 * 10^{-3} =\frac{V}{22.4}\\ V\ =\ 150.6mL[/tex]
This can be written as 151mL
In general,for a gas at a constant volume?
Answer:
The pressure of a gas is directly proportional to its Kelvin temperature if the volume is kept constant. At constant volume and temperature, the total pressure exerted by a mixture of gases is equal to the sum of the partial pressures of the component gases.
Explanation:
3. Are all amino acids are chiral? Why or why not? Protein only contain ____ (L-/D-) amino acids. Which organic molecule is the standard molecule for L-/D- configuration system? The chiral carbon in L-Alanine is ______ (R- /S-) configuration, but in D-Alanine is ________ (R-/S-) configuration.
Answer:
Protein are essential in body cells for the repair of worn out tissues. Amino acid is gotten when protein is broken down under certain conditions.
All amino acids are chiral with the exception of glycine. This means they have a central carbon atom with the R-, -COOH, and -NH2 group attached to it.
Protein contain only L amino acid because the L amino acid is the only type used by cells.
The chiral carbon in L-Alanine is S-configuration and D-Alanine is R-configuration.
The metalloid that has three valence electrons is .
Answer:
Boron
Explanation:
Answer: a. boron
Explanation: bc the Boron Family is named after the first element in the family. atoms in this family have 3 valence electrons. this family includes a metalloid (boron), and the rest are metals.
Match the following aqueous solutions with the appropriate letter from the column on the right. 1. 0.13 m FeCl3 A. Highest boiling point 2. 0.19 m Mg(CH3COO)2 B. Second highest boiling point 3. 0.30 m KI C. Third highest boiling point 4. 0.53 m Glucose(nonelectrolyte) D. Lowest boiling point An error has been detected in your answer. Check for typos,
Answer:0.30 m KI ---- A. Highest boiling point
0.19 m Mg(CH3COO)2 ---- B. Second highest boiling point
0.53 m Glucose(nonelectrolyte) ---- Third highest boiling point-C
0.13 m FeCl3---- Lowest boiling point-D
Explanation:
Using the boilng point elevation formula
ΔTb=m* kb *i
where m= molality
kb= elevated boiling point constant( here kb values will be same for all soluton)
i= vant hoff factor = number of ions present in a solution
Using the number of ions and molarity present in a solution as a collagative property, since kb is constant, we can determine which of the species has the highest boiling point.
1.) 0.13 m FeCl3= Fe³⁻ + Cl⁻
i=4
ΔTb=m* kb* i= molarity x number of ionsx Kb= 0.13 x 4= 0.52kb
2) 0.19 m Mg(CH3COO)2 = Mg²⁺ + CH₃COO⁻
i= 3
ΔTb=m* kb* i= molarity x number of ions= 0.19 x 3= 0.57kb
3. 0.30 m KI = K⁺ + I⁻
i= 2
ΔTb=m *kb *= imolarity x number of ions xKb= 0.30x 2= 0.60kb
4. 0.53 m Glucose(nonelectrolyte) =
i= 1 for nonelectroytes
ΔTb=m* kb* i = molarity x number of ionsx Kb= 0.53 x 1= 0.53Kb
therefore,
0.30 m KI ---- A. Highest boiling point
0.19 m Mg(CH3COO)2 ---- B. Second highest boiling point
0.53 m Glucose(nonelectrolyte) ---- Third highest boiling point
0.13 m FeCl3---- Lowest boiling point
Two hypothetical ionic compounds are discovered with the chemical formulas XCl2 and YCl2, where X and Y represent symbols of the imaginary elements. Chemical analysis of the two compounds reveals that 0.25 mol XCl2 has a mass of 100.0 g and 0.50 mol YCl2 has a mass of 125.0 g. (a) What are the molar masses of XCl2 and YCl2
Answer:
THE MOLAR MASS OF XCL2 IS 400 g/mol
THE MOLAR MASS OF YCL2 IS 250 g/mol.
Explanation:
We calculate the molar mass of XCL2 and YCL2 by bringing to mind the formula for molar mass when mass and amount or number of moles of the substance is given.
Number of moles = mass / molar mass
Molar mass = mass / number of moles.
For XCL2,
mass = 100 g
number of mole = 0.25 mol
So therefore, molar mass = mass / number of moles
Molar mass = 100 g / 0.25 mol
Molar mass = 400 g/mol.
For YCL2,
mass = 125 g
number of mole = 0.50 mol
Molar mass = 125 g / 0.50 mol
Molar mass = 250 g/mol.
So therefore, the molar mass of XCL2 and YCL2 IS 400 g/mol and 250 g/mol respectively.
Identify the particle represented by each symbol as an alpha particle, a beta particle, a gamma ray, a positron, a neutron, or a proton.
a. 11P
b. 42He
c. +10e
Answer:
[tex]_1^{1} {P}[/tex] is symbol for proton emission in the nucleus.
[tex]_2^{4} {He}[/tex] symbolises alpha emission, equivalent to helium atom emission of a radioactive particle
[tex]+_1^{0} {e}[/tex] is the radiation symbol for positiron particle. which occurs when beta + radioactive decay occurs
A sample of thallium(III) peroxide, Tl2(O2)3, contains 2.45 mol of thallium(III) ions. The number of moles of peroxide ions in the sample is
Answer:
The correct answer is 3.675 moles.
Explanation:
Based on the question, the reaction taking place is,
Tl₂(O₂)₃ ⇒ 2Tl⁺³ + 3O₂⁻²
Thus, 1 mole of thallium peroxide comprise 2 moles of thallium and 3 moles of peroxide ions.
However, based on the given question, a sample of thallium peroxide comprise 2.45 moles of thallium ions. The moles of peroxide ions present in the sample will be,
= 2.45 × 3 / 2
= 3.675 moles.
Hence, the moles of peroxide ions present in the given sample is 3.675.
Constructive interference occurs when the compression of one wave meets
up with the compression of a second wave.
A. True
B. False
Answer:
True
Explanation:
Which of the following obervations would be classified as a physical change? A) Fireworks releasing light B) Antacid fizzing in water C) Steam condensing on a mirror D) Apple turning brown
Answer:
C) Steam condensing on a mirror
Explanation:
This was just a change in the physical state.
What is the rate of a reaction if the value of kis 0.1, [A] is 1 M, and [B] is 2 M?
Rate = K[A]2[B]2
A. 1.6 (mol/L)/s
B. 0.8 (mol/L)/S
C. 0.2 (mol/L)/S
D. 0.4 (mol/L)/S
Answer:
D. 0.4 (mol/L)/S
Explanation:
You simply have to plug in the given values into the rate law.
Rate = k[A][B]
Rate = (0.1)(1)²(2)²
Rate = (0.1)(1)²(4)²
Rate = 0.4
A student sets up the following equation to solve a problem in solution stoichiometry. (The ? stands for a number the student is going to calculate.) Enter the units of the student's answer
(1.26mol)1mL10^−3L / (7.9mol/L)= ?
Answer:
mL * L²
Explanation:
The question in t his problem is to calculate the units of the final answer.
The units in the numerator is mol, ml and L.
The unit in the denominator is mol/L
This leads us to;
Numerator / Denominator = mol * mL * L / (mol / L )
The final units is mL * L²
Combustion analysis of a 13.42-g sample of the unknown organic compound (which contains only carbon, hydrogen, and oxygen) produced 39.61 g CO2 and 9.01 g H2O. The molar mass of equilin is 268.34 g/mol. Find its molecular formula.
Answer: The molecular formula for the given organic compound is [tex]C_{18}H_{20}O_2[/tex]
Explanation:
The chemical equation for the combustion of hydrocarbon having carbon, hydrogen and oxygen follows:
[tex]C_xH_yO_z+O_2\rightarrow CO_2+H_2O[/tex]
where, 'x', 'y' and 'z' are the subscripts of Carbon, hydrogen and oxygen respectively.
We are given:
Mass of [tex]CO_2=39.61g[/tex]
Mass of [tex]H_2O=9.01g[/tex]
We know that:
Molar mass of carbon dioxide = 44 g/mol
Molar mass of water = 18 g/mol
For calculating the mass of carbon:
In 44 g of carbon dioxide, 12 g of carbon is contained.
So, in 39.61 g of carbon dioxide, [tex]\frac{12}{44}\times 39.61=10.80g[/tex] of carbon will be contained.
For calculating the mass of hydrogen:
In 18 g of water, 2 g of hydrogen is contained.
So, in 9.01 g of water, [tex]\frac{2}{18}\times 9.01=1.00g[/tex] of hydrogen will be contained.
Mass of oxygen in the compound = (13.42) - (10.80 + 1.00) = 1.62 g
To formulate the empirical formula, we need to follow some steps:
Step 1: Converting the given masses into moles.Moles of Carbon = [tex]\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{10.80g}{12g/mole}=0.9moles[/tex]
Moles of Hydrogen = [tex]\frac{\text{Given mass of Hydrogen}}{\text{Molar mass of Hydrogen}}=\frac{1g}{1g/mole}=1moles[/tex]
Moles of Oxygen = [tex]\frac{\text{Given mass of oxygen}}{\text{Molar mass of oxygen}}=\frac{1.62g}{16g/mole}=0.10moles[/tex]
Step 2: Calculating the mole ratio of the given elements.For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 0.10 moles.
For Carbon = [tex]\frac{0.9}{0.10}=9[/tex]
For Hydrogen = [tex]\frac{1}{0.10}=10[/tex]
For Oxygen = [tex]\frac{0.10}{0.10}=1[/tex]
Step 3: Taking the mole ratio as their subscripts.The ratio of C : H : O = 9 : 10 : 1
Hence, the empirical formula for the given compound is [tex]C_9H_{10}O[/tex]
For determining the molecular formula, we need to determine the valency which is multiplied by each element to get the molecular formula.
The equation used to calculate the valency is :
[tex]n=\frac{\text{Molecular mass}}{\text{Empirical mass}}[/tex]
We are given:
Mass of molecular formula = 268.34 g/mol
Mass of empirical formula = 134 g/mol
Putting values in above equation, we get:
[tex]n=\frac{268.34g/mol}{134g/mol}=2[/tex]
Multiplying this valency by the subscript of every element of empirical formula, we get:
[tex]C_{(9\times 2)}H_{(10\times 2)}O_{(1\times 2)}=C_{18}H_{20}O_2[/tex]
Thus, the molecular formula for the given organic compound is [tex]C_{18}H_{20}O_2[/tex].
How many moles would 1.204x1024 atoms of oxygen be? (Remember Avogadro's number is 6.022x1023
Answer:
7.25 x 10^47
Explanation:
1.204 x 10^24 moles*6.022 x 10^23 avogadro's number= 7.25 x 10^47
At the end of a reaction it is important to remove the solvent from a solid product (more than one answer may be correct):
a. So that the melting point can be determined.
b. So that clean NMR spectra can be obtained that do not contain solvent peaks.
c. So that the yield can be determined.
d. So that the solvent can be reused.
Answer:
(B.) and (C.)
b. So that clean NMR spectra can be obtained that do not contain solvent peaks.
c. So that the yield can be determined.
Explanation:
The solvent used in Nuclear Magnetic Resonance (NMR) spectrometer is Trimethyl silane (TMS), a neutral solvent which doesn't give off any signals. Other solvents could have interactions with the radiation, and disrupt the spectra.
Furthermore, for accurate determination of the actual yield and overall percentage yield, solid must be separated from the solvent, dried and weighed.
I hope this was explanatory enough.
In redox half-reactions, a more positive standard reduction potential means I. the oxidized form has a higher affinity for electrons. II. the oxidized form has a lower affinity for electrons. III. the reduced form has a higher affinity for electrons. IV. the greater the tendency for the oxidized form to accept electrons.
Answer:
The 1st and 4th options are correct
I.the oxidized form has a higher affinity for electrons
IV. the greater the tendency for the oxidized form to accept electrons
Explanation:
Half reaction can be described as the oxidation or reduction reaction in a redox reaction.it is In the redox rection there is a change in the oxidation states of Chemical species involved. the oxidized form in the redox has a higher affinity for electrons and the greater the tendency for the oxidized form to accept electrons.
Standard reduction potential which is also referred to as standard cell potential can be described as the potential difference that exist between cathode and anode of the cell. In the standard reduction potential most times the species will be reduced which is usually analysed in a reduction half reaction.
(Standard Hydrogen Electrode) is utilized when determining the Standard reduction or potentials of a chemical specie. this is because of Hydrogen having zero reduction and oxidation potentials, as a result of this a measured potential of any species is compared with that of Hydrogen, the difference helps to know the potential reduction of that particular specie.
How many molecules of water are in 5 moles
Answer:
3.011x10^24 molecules
Explanation:
1 mole=6.022x10^23 molecules
5 moles*6.022x10^23 molecules/mole=3.011x10^24 molecules
Calcium carbonate can break down to form calcium oxide and carbon dioxide.
CaCO3 → CaO + CO2
The oxygen atoms on the product side are
Answer:
balanced because the total number of oxygen atoms is 3.
