Point A: This is the point where the pH corresponds to a solution of H2A in water. At this point, the solution is mainly composed of undissociated H2A molecules, so the pH of the solution is equal to the pKa1 of the acid.
What is solution?Solution can be defined as a method for solving a problem, dispute, or difficult situation. It is a way to overcome obstacles and find a positive outcome.
b) Point B: This is the point where the pH corresponds to a solution of HA in water. At this point, the solution is mainly composed of partially dissociated HA molecules, so the pH of the solution is equal to the pKa1 of the acid.
c) Point C: This is the point where the pH corresponds to a solution of A in water. At this point, the solution is mainly composed of fully dissociated A molecules, so the pH of the solution is equal to the pKa2 of the acid.
d) Point D: This is the point where the pH corresponds to the pKa1 of the acid. At this point, the solution is in equilibrium between the undissociated H2A molecules and the partially dissociated HA molecules, so the pH of the solution is equal to the pKa1 of the acid.
e) Point E: This is the point where the pH corresponds to the pKa2 of the acid. At this point, the solution is in equilibrium between the partially dissociated HA molecules and the fully dissociated A molecules, so the pH of the solution is equal to the pKa2 of the acid. This point is reached when the total volume of titrant added is equal to the total volume of acid, which is usually equal to the second pKa of the acid times the volume of the acid.
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where is the highest ionization energy in the periodic table
Answer: Helium has the largest first ionization energy while francium has one of the lowest.
Explanation: The first ionization energy varies in a predictable way across the periodic table. The ionization energy decreases from top to bottom in groups, and increases from left to right across a period.
Which of the following hybridization schemes allows the formation of at least one π bond?
a. SP^3
b. SP^2
c. SP^3D^2
Just the sp2 hybridization seems to have a free p orbital among the sp3, sp2, and sp3d hybridization schemes. It therefore permits the development with at least one bond.
How does chemistry define hybridization?A new form of hybridized orbitals is created by combining two atomic orbitals, which is known as hybridization in chemistry. Hybrid orbitals with completely distinct energies, forms, etc. are typically created as a result of this intermixing.
In basic terms, what is hybridization?When two single-stranded DNA or RNA molecules are complementary to one another, they can hybridize to generate a double-stranded molecule. The right base pairing between both the two single-stranded polymers is required for the bonding to occur.
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which of the molecules or ions below will have the strongest nitrogen-oxygen bond? no+, no2 −, no3 −
NO3− will have the strongest nitrogen-oxygen bond. This is because the bond is formed through the sharing of three electron pairs between the two atoms.
What is bond?Bond is a type of debt security that allows an investor to loan money to a government, municipality, corporation, or other entity in exchange for the promise of regular payments and the return of the principal upon maturity. Bonds are typically issued with a fixed rate of interest and a stated maturity date. Bonds are typically seen as a relatively safe investment, since the issuer is usually obligated to repay the principal. Bonds may be traded on the secondary market, allowing investors to capitalize on changes in the interest rate environment. Bonds may also provide tax advantages, depending on the type and issuer.
This creates a stronger bond than the two electron pairs shared in NO+ or the single electron pair shared in NO2−.
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heat is added to boiling water. explain why the temperature of the boiling water does not change. what does change?
As a result of the heat being absorbed by the water, which provides the energy needed to partially break intermolecular attraction interactions in the liquid and cause a transition to gaseous water, the liquid turns into a solid phase.
Gaseous water is present where?The hydrosphere contains gaseous water, or water vapor. For instance, when we boil water, the air is filled with the vapor that results from the water being heated.
Describe a gaseous water example.We are constantly surrounded by the vapor of water, which is a gas. It is invisible. Water transforms into a gas and water vapor when it is boiled. We observe a little cloud known as steam as a portion of the vapour cools.
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The light and dark circles in the picture represent different types of atoms. Which picture best represents a pure compound?
The third image is a pure compound since it only contains one kind of atom combination. (C)
A pure compound is one that has two or more elements chemically combined in a specific ratio. Chemical techniques can split these compounds into independent or straightforward constituents. A pure compound is created when elements are linked together by chemical bonds. substances that are as pure as water, crystals, and baking soda.
Oxygen and hydrogen combined in a fixed ratio to form the compound water. A pure substance has a single type of constant-composition atom or molecule. The first image depicts a pure material, while the second and fourth images show mixed compounds. Consequently, the third image depicts a pure compound.
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IR spectroscopy of cyclohexanol Definition
The infrared radiation study of the molecule is called IR spectroscopy. This spectroscopy is of lower energy and higher wavelength which is used to probe the different functional groups present in a molecule by vibrating the bond of the molecules.
By vibrating the bonds between the molecules, this spectroscopy, which has a lower energy and longer wavelength, is used to examine the various functional groups that are present in a molecule.
What is the cyclohexanone IR frequency?
In the range of 4000-150 cm-1, the infrared spectra of cyclohexane in both its liquid and vapor phases have been investigated. The infrared band caused by the vibration of the Eu skeletal deformation was discovered at 248 cm1.
What does the term "IR spectroscopy" mean?
The IR spectroscopy theory is based on the idea that molecules have a tendency to absorb particular light frequencies that are unique to the corresponding structure of the molecules.
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A group of other students wanted to know if citric acid and baking soda produce any other gas, so they heated the left over liquid and measured density and found out that liquid is water but the left over gas is 4.2 grams more than they had at the start. How is it possible for citric acid and baking soda to create water?
It is possible for citric acid and baking soda to create water because they are both chemical compounds that can react with each other to create new compounds.
When citric acid and baking soda are mixed together, they undergo a chemical reaction known as a neutralization reaction. This type of reaction occurs when an acid and a base react to form salt and water.
In this case, citric acid is an acid and baking soda is a base. When they are mixed together, the acid and base neutralize each other, creating a salt compound and water. The acid and base cancel out each other's properties and neutralize the solution. The acid donates a proton (H+) to the base, and the base accepts it to form water.
The gas that was measured by the students, is the carbon dioxide (CO2) that is produced as a byproduct of this reaction. As the acid and base react, they release carbon dioxide gas, which is 4.2 grams more than they had at the start. The reaction can be written as follows:
[tex]C_{6}[/tex][tex]H_{8}[/tex][tex]O_{7}[/tex] [tex]_{(aq)}[/tex] + [tex]NaHCO_{3}[/tex] [tex]_{(s)}[/tex] → [tex]NaC_{6}[/tex][tex]H_{5}[/tex][tex]O_{7}[/tex] [tex]_{(aq)}[/tex] + [tex]H_{2} O[/tex] [tex]_{(l)}[/tex] + [tex]CO_{2}[/tex] [tex]_{(g)}[/tex]
In conclusion, citric acid and baking soda produce water and carbon dioxide (CO2) when they react together in a neutralization reaction. The reaction creates a new compound, salt, and water, while the gas created is carbon dioxide.
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If you combine the results of this question with the results from question 3b, what do you know about the total ph change caused by adding the last 0.1 ml of hno3
The total pH change caused by adding the last 0.1 ml of HNO3 would be a decrease of 0.5.
What is pH?pH is a measure of the acidity or alkalinity of a solution. It is a measure of the hydrogen ion concentration, and is expressed on a scale from 0 to 14. A pH of 7 is considered neutral, a pH below 7 is acidic and a pH above 7 is alkaline. A solution with a pH of 0 is very acidic, and a solution with a pH of 14 is very alkaline
This is because the pH of the solution decreased by 0.5 when 0.1 ml of HNO3 was added in question 3b.
As this was the last addition of HNO3, no more pH change can be expected and thus the total pH change caused by adding the last 0.1 ml of HNO3 would be 0.5.
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The vapor pressures (in torr) of solid and liquid uranium hexafluoride are given by
ln(Ps)=24.513−5892.5 KTln(Ps)=24.513−5892.5 KT
ln(Pl)=17.357−3479 KTln(Pl)=17.357−3479 KT
where T is the absolute temperature. Calculate the temperature and pressure at the triple point of uranium hexafluoride.
T= _____ K
P=____torr
When T is the absolute temperature, then 5892.5 K In (Ps) = 24.513 3479 K ln (P) = 17.357 gives the vapor pressures (in torr) of solid and liquid uranium hexafluoride.
What is the purpose of uranium hexafluoride?Because of its special qualities, uranium hexafluoride is employed in the processing of uranium. It can be utilized easily as a liquid to fill or empty equipment or containers, or as a gas for processing.
Where does uranium hexafluoride come from?In the process of gaseous diffusion, mined uranium ore is delivered to a facility that turns it into uranium oxide, also referred to as "yellowcake." The next step is to chemically create uranium hexafluoride by combining uranium oxide with hydrogen fluoride and fluorine gas.
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1. Hydrogen can be prepared by reacting zinc with dilute hydrochloric acid. a) Write an equation for the reaction. b) Name an appropriate drying agent for hydrogen gas. c) Explain why copper metal cannot be used to prepare hydrogen gas. d) Hydrogen burns in oxygen to form an oxide. (i) Write an equation for the reaction. (ii) State two precautions that must be taken before the combustion begins and at the end of the combustion. e) Give two uses of hydrogen gas. f) When zinc is heated to redness in a current of steam, hydrogen gas is obtained. Write an equation for the reaction. g) Element Q reacts with dilute acids but not with cold water. Element R does not react with dilute acids. Elements S displaces element P from its oxide. P reacts with cold water. Arrange the four elements in order of their reactivity, starting with the most reactive. h) Explain how hydrogen is used in the manufacture of margarine. 2. (a) Hydrogen can reduce coppers Oxide but not aluminium oxide. Explain (b) When water reacts with potassium metal the hydrogen produced ignites Explosively on the surface of water. (i) What causes this ignition? (ii) Write an equation to show how this ignition occurs 3. Element E has an atomic number of 5. In a sample of E there are two isotopes. One isotope has a mass number of 10 and the other isotope has a mass number of 11. a. Explain, in terms of subatomic particles, what is meant by the term isotopes. b. Element X has an atomic number of 18. c. State the electronic configuration of an atom of element X. 4. The electronic structures of five atoms, A, B, C, D and E, are shown. D Answer the following questions about these structures. Each structure may be used once, more than once or not at all. State which structure, A, B, C, D or E, represents: a. An atom of a metallic element. b. An atom with a proton number of 13. C. An atom of phosphorus. d. An atom with only two shells of electrons. e. An atom which forms a stable ion with a single negative charge.
All of the zinc reacts, increasing the solution's temperature from 22.5 °C to 23.7 °C.
What is the chemical equation for the reaction between zinc and hydrochloric acid?According to the balanced equation, zinc metal interacts with hydrochloric acid: ZnCl2(aq) + H2 Zn(s) + 2 HCl(aq) ( g) In a coffee-cup calorimeter, 0.103 g of Zn(s) are mixed with 50.0 mL of HCl to create a solution. All of the zinc reacts, increasing the solution's temperature from 22.5 °C to 23.7 °C.Below copper in the electrochemical chain lies hydrogen. When zinc and diluted hydrochloric acid react, zinc releases hydrogen gas but copper does not.Zinc reacts with diluted HCl to produce hydrogen gas and zinc chloride.Zn+2HCl->ZnCl + HTo learn more about hydrochloric acid refer to:
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What mass of NH4NO3 (mw=80.04g/mo) should be used to make 2.50 mL of 6.5 mM NH4NO3?
Answer:
Explanation:
Molarity = 6.5 x 10^(-3)
mass x 2.50/80.04 x 1000 = 6.5x 10^(-3)
mass = 6.5x 10^(-3) x 80.04 x 1000/2.50
mass = 208.104 grams
Which of these are consequences of an increase in long-run aggregate supply? Correct Answer(s) Drag appropriate answer(s) here an increase in the price level an increase in full-employment output an increase in short-run aggregate supply a decrease in the long-run rate of unemployment u*
Drag the proper The short run balance output and market price for the economy is where the collective supply line meets the money supply line.
What elements alter aggregate supply over the long term?elements , labor, and knowledge are the only variables that affect the aggregate supply curve over the long term. The graph may shift towards the right as a result of increased capital, more labour availability, and improved technology because it is vertical with in long run.
What happens when aggregate supply rises over the long term?Consumers battle for the available commodities and pay more when demand rises in the face of steady supply. Due to this dynamic, businesses boost output in an effort to increase sales. Prices normalize as a result of the increased supply, while output stays high.
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suppose that a new temperature scale has been devised on which the melting point of ethanol (-117.3oc) and the boiling point of ethanol (78.3oc) are taken as 0os and 100os, respectively, where s is the symbol for the new temperature scale. derive an equation relating a reading on this scale to a reading on the celsius scale. what would this thermometer read at 25oc?
The thermometer would read 40.5°S at 25°C based on new temperature scale.
How to derive the equation for new temperature scale?An equation relating a reading on the new temperature scale (s) to a reading on the Celsius scale can be derived using the two known points of ethanol's melting and boiling points. The freezing point of ethanol is -117.3oc and the boiling point is 78.3oc. So, the equation can be expressed as follows:
S = (100/195.6)*(C + 117.3);
Where S = reading on the new temperature scale;
C => reading on the Celsius scale.
s = (100/195.6)*(25 + 117.3) = 40.5
Therefore, this thermometer would read 40.5°S at 25°C.
It's important to note that this is a hypothetical temperature scale, and it only applies to the freezing and boiling points of ethanol. It doesn't have any practical use and it's not a standard temperature scale like Celsius or Fahrenheit. Also, the freezing and boiling points of ethanol are not constant, they depend on the pressure and the purity of the ethanol.
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what organization has established a set of chemical-protective ppe ensembles providing certain protection levels that are commonly used by fire and emergency service organizations?
First responders must have a minimal level of protection against toxic vapours, liquids, and particles during hazardous materials situations, according to the NFPA Protective Ensemble Classes.
What gas is the most toxic vapour?
The most prevalent hazardous gas is odourless, colourless carbon monoxide. It mixes quickly and is easily inhaled because of its comparable density to air. It is a well-known "silent killer" in residential settings. Carbon monoxide is likely to be produced by any process that results in the incomplete burning of carbon fuel.
What is the earth's most toxic vapour?
N2 is the most deadly of all damaging, risky, and toxic gases because it is composed of nitrogen. It is widely distributed in the atmosphere because it is the element that humans breathe in most frequently. There are gases called nitric oxide & nitrogen dioxide in a lot of industrial and home situations.
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What acid and what base would you choose to prepare the salt potassium perchlorate (KClO4)?
a. HK and ClO4OH
b. KOH and H2ClO4
c. K(OH)2 and HClO4
d. HClO4 and KOH
Which combination of HClO4 & KOH acid & base would you use to make the potassium perchlorate salt (KClO4)
What purposes is potassium perchlorate used?Potassium perchlorate is a crystalline (sand-like) solid that ranges from colorless to white. It is used in medicine, explosives, flares, rockets propellants, photography, air bags for car safety, and rocket propellants.
Where can I find potassium perchlorate?In the manufacturing process, potassium chloride is added to a sodium perchlorate aqueous solution to create potassium perchlorate. This solitary precipitation reaction takes advantage of KClO4's limited solubility.
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calculate the volume in milliliters of a 1.33 m calcium bromide solution that contains of calcium bromide . be sure your answer has the correct number of significant digits.
The volume of 1.33 mol/L calcium bromide solution that contains 125 g of calcium bromide is 470 mL
The volume can be calculate as follows:
First we should calculate the moles of calcium bromide
The moles of calcium bromide = Mass/ mass molar
The moles of calcium bromide = 125 g / 199.89 g/mol
The moles of calcium bromide = 0.625 moles
from de question we know that the molar of the solution is 1.33 mol/l
we also know that Molar = moles/ volume
so the volume is gonna be
volume= moles/ molar
volume = 0.625 moles/ 1.33 mol/L = 0.47 L = 470 mL
Therefore, the volume of 1.33 mol/L calcium bromide solution that contains 125 g of calcium bromide is 470 mL
Your question is incomplete but most probably your full question was
calculate the volume in milliliters of a 1.33 mol/L calcium bromide solution that contains 125 g of calcium bromide . be sure your answer has the correct number of significant digits.
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How many grams of lioh are needed to make 100 ml of a 0.1 m solution?
0.24 grams needed to make this solutions.
What is meant by grams?
The International System of Units (SI) defines the gram as one thousandth of a kilogram of mass.The term "absolute weight" was first used in a definition from 1795 that stated, "the absolute weight of a volume of pure water equal to the cube of a hundredth part of a metre [1 cm3], and at the temperature of melting ice." Later, the definition's defining temperature (0 °C) was changed to4 °C, the temperature at which water has its maximum density.
By the late 19th century, however, there was a push to make the kilogram the base unit and the gram a derived unit.A gram was defined as one thousandth of a kilogram by the new International System of Units in 1960.Volume = 100 ml
Molarity (M) = 0.1M
Molecular weight of LiOH => 7 + 16 + 1= 24
Formula here we use is :- 1 × 1000 / 24 × 100
w = 0.24g
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I'm begging just help me if you know the answer:
how does the temperature affect on concentration (liquid) of NaOH (sodium hydroxide?
Answer:
The solubility of sodium hydroxide decreases with increase of temperature. Equilibrium constant of an exothermic reaction decreases with increase of temperature. Due to this less heat is produced in the reaction and the effect of increased temperature is nullified.
ind pH in the following solution if their [H^+] concentration is : a) [5x10^-9 ml/dm^3]
Answer:
8.301
Explanation:
just calculate -log (5×10*-9)
Determine the mole fraction of vinyl chloride and vinylacetate in a copolymer having a molecular weight of 10520 g/mol and a degree of polymerization of 160.
0.5 moles of the mole fraction of vinyl chloride and vinylacetate in a co-polymer having a molecular weight of 10520 g/mol.
Given,
mass= 10,000 g/mol
DP= 200
mass of vinyl chloride = 62.5 g/mol
mass of vinyl acetate = 86 g/mol
Lets the mole fraction be X
required mole fraction be (1-x)
Mass of vinyl chloride=62.5 x
Mass of vinyl acetate =86(1-x)
mass of monomer = 62.5 x + 86 (1-x)
weight of polymer = DP x Mass of monomer
= 10,000 =200(62.5 x + 86 - 86 x)
= 23.5 x = 36
x=0.5
Polymeric compounds which are built up of two different types of monomer units in their chain are called ―Copolymers or ―Mixed polymer polymers with three different types of nonnumeric units are sometimes called as ter-polymer.
Copolymers are further classified as alternating copolymers or statistically regular (where both repeating bunits are joined side by side) and random copolymers or statistically irregular (where there is no regularity in the joining of units of two different monomers.
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when two atoms of 2h are fused to form one atom of 4he, the toal energy involved in 3.38 x 10-12j. what is the total change in mass (in kg) for this reaction?
The total change in mass for this reaction is 4.82 x 10-27 kg.
What is reaction?Reaction is an action by a person or organism in response to a stimulus. Reactions can be physical, mental, or emotional. Reactions can involve physiological changes, such as increased heart rate or sweating, as well as cognitive changes, such as increased alertness or fear. Reactions can also involve behavioral changes, such as avoidance or aggression. In some cases, reactions may involve a combination of physical, mental, and behavioral responses.
This is calculated using the formula E = mc^2, where E is the total energy involved in the reaction (3.38 x 10-12J), m is the total change in mass, and c is the speed of light (2.99 x 10^8 m/s).
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predict the sign of the entropy change, δs∘, for each of the reaction displayed. Drag the appropriate items to their respective bins.
Help
Reset
Ag+(aq)+Cl−(aq)→AgCl(s)
2KClO3(s)→2KCl(s)+3O2(g)
2N2O(g)→2N2(g)+O2(g)
2Mg(s)+O2(g)→2MgO(s)
C7H16(g)+11O2(g)→7CO2(g)+8H2O(g)
H2O(l)→H2O(g)
Positive
Negative SubmitHintsMy AnswersGive UpReview Part
The predicted sign of the entropy change in each reaction are as follows;
Ag+(aq). + Br−(aq) → AgBr(s). --Negative
CaCO3(s) → CaO(s)+CO2(g) --Positive
2NH3(g) → N2(g)+3H2(g) --Positive
2Na(s). + Cl2(g) → 2NaCl(s) --Negative
C3H8(g)+5O2(g)→3CO2(g)+4H2O(g) --Positive
I2(s) → I2(g). --Positive
What is entropy change?Entropy of a system or chemical entity is the degree of disorderliness in the substance. The change in entropy, ΔS∘ is a measure of the difference between the entropy of products and the reactants and is given mathematically as ΔS∘ = S(products) - S(reactants).
Here,
Following are the reactions' predicted entropy changes and their predicted signs:
Ag+(aq). + Br−(aq) → AgBr(s). --Negative
CaCO3(s) → CaO(s)+CO2(g) --Positive
2NH3(g) → N2(g)+3H2(g) --Positive
2Na(s). + Cl2(g) → 2NaCl(s) --Negative
C3H8(g)+5O2(g)→3CO2(g)+4H2O(g) --Positive
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Determine the pH of a 0.232 M Mg(OH)2 solution at 25°C A. 13.67 B. 13.37 C. 0.634 D. 12.73 E. 0.333
the pH of a 25°C, 0.232 Mg(OH)2 solution Mg(OH)2 is dissolved as Mg(OH)2 = Mg2+ + 2 OH- 0.232 M —-0.232 M in the following order: A. 12.78 B. 13.37 B ) 0.634 D. 15.32 E. 0.333
What pH does a 0.20 M naoh have?to 0.70
Since a strong acid like nitric acid completely dissociates, the hydronium ion's concentration is also equivalent to 0.20 Metres acid. With this information, we can now determine the method's pH level. The solution has a pH of exactly 0.70.
How do you determine pH?You have to know the hydronium ion concentration in mole per liter to determine overall pH of an aqueous phase (molarity).After that, the pH is determined using the formula pH ≈ - log [H3O+]. You can alternatively write the pH Formula as. l o g [H +] = p H Problems With the pH Formula. Problem 1: Determine the ph of a solution in which there are 8.0 10-8M hydronium ions.
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why were scientists hesitant to support wegener and hess when they first presented their hypotheses.
Scientists were hesitant to support wegener and hess when they first presented their hypotheses just because of the conflict of stability of the continents and the ocean floor.
Scientists were hesitant to support Wegener and Hess when they first presented their hypotheses because their ideas went against the widely accepted scientific understanding of the time. Wegener's theory of continental drift, which proposed that the continents had once been part of a single landmass and had since moved apart, was not supported by any credible evidence or mechanism. Hess's theory of sea floor spreading, which proposed that new oceanic crust was being created at mid-ocean ridges and pushed away from them, was also not supported by any conclusive evidence. Additionally, both hypotheses conflicted with the prevailing belief in the permanence and stability of the continents and the ocean floor. These factors made it difficult for scientists to accept their ideas, despite the growing evidence in support of them.
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which of the following statements best helps to explain why the contents of the tube containing the equilibrium mixture turned a lighter color when the tube was placed into an ice bath? (a) the forward reaction is exothermic. (b) the forward reaction is endothermic. (c) the ice bath lowered the activation energy. (d) the ice bath raised the activation energy.
The mixture as per the question is endothermic reaction when the contents of the tube containing the equilibrium mixture turned a lighter color whenever the tube was placed into an ice bath.
Activation energy can be defined as the minimum energy required by particles at the reactant side for a chemical reaction to occur. According to the reaction conditions, specifically for reversible reactions, reactants can in turn become products and vice versa.
Exothermic reaction can be defined as the process where the heat energy is liberated in the conversion of the reactants to products for the forward reaction. We know that the heat is created in this process a small part of the energy may be initially provided to activate the reactant particles but once the reaction is in ongoing state it produces good amount of heat energy to keep the process in flow.
The reverse reaction, we know that is the endothermic in nature. The heat energy is absorbed in the conversion of the products ( now reactants in the reverse reaction ) to reactants ( now products in the reverse reaction ), as a result of this more amount of energy has to be initially and continuously supplied for them to overcome the activation energy barrier for the reverse reaction to occur and be sustained.
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Helium-neon lasers emit very high spectral purity red light at a wavelength of 632.8 nm, and were used in LaserDisc players and supermarket checkout barcode scanners. A large-cavity He-Ne laser has a volume of 0.785 L, and is filled with a mixture of 90.0% helium and 10.0% neon at a pressure of 1.00 torr. What is the mass of helium (in mg) in this laser at 25.0 °C? (760 torr = 1 atm)
Using ideal gas law, the mass of helium in the laser is 1.5*10⁻³mg
What is Ideal Gas LawTo determine the mass of helium in the laser, we need to first calculate the number of moles of helium and neon in the laser. We can then use the molar mass of helium to convert the number of moles to mass.
Given that the laser has a volume of 0.785 L and is filled with a mixture of 90.0% helium and 10.0% neon at a pressure of 1.00 torr at 25.0 °C, we can use the ideal gas law to calculate the number of moles of each gas.
The ideal gas law is PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature in Kelvin.
R = 8.314 J/mol.K
T = 25.0 + 273 = 298 K
Given that the pressure is 1.00 torr, we need to convert it to atm, which is the same unit as R.
1 torr = 1/760 atm
so, P = 1.00 torr / 760 atm = 0.0013158 atm
now we can calculate the number of moles of the gas in the laser:
n = PV / RT = 0.0013158 atm * 0.785 L / (8.314 J/mol.K * 298 K) = 4.17*10⁻⁷ moles
To find out the number of moles of helium and neon, we can use the percentage composition:
nHe = 4.17*10⁻⁷ moles * 90.0% = 3.753*10⁻⁷ moles
nNe = 4.17*10⁻⁷ moles * 10.0% = 4.17*10⁻⁸ moles
The molar mass of helium is 4.003 g/mol
We can use the number of moles and molar mass to find the mass of helium in the laser:
mass = nHe * molar mass = 3.753*10⁻⁷ moles * 4.003 g/mol = 1.5 *10⁻³mg
Therefore, the mass of helium in the laser is 1.5 * 10⁻³mg.
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All of the following statements about lighteners are true EXCEPT:a) they are used at relatively high levelsb) they slowly block the production of melanin in the skinc) they are used to bleach or lighten areas of hyperpigmentationd) they usually take months of continued use to deliver a noticeable effect
With the exception of (a), all of the following statements regarding lighteners are true.
What causes hyperpigmentation?Melanin, a pigment made by skin cells, is what gives skin their colour. The skin cells may produce far to much melanin if they are sick or injured. There might be a melanin deposition there, darkening it up. Fading could take a while after the dark spots and patches' root causes have been identified and eliminated. An area that is just a few shades darker than you natural skin color takes 6 to 12 months to heal on average. Blue-gray-appearing hyperpigmentation in the dermis may last a long time or become permanent if addressed.
Which serum is best for hyperpigmentation?Lightweight Anti-Pigmentation Serum: Clinical studies have shown that the advanced skin-lightening ingredient Alpha Arbutin, which is included in this de pigmentation serum, reduces hyperpigmentation and blemishes.
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A mixture is made by mixing alcohol, water and salt then how will you seperate the componen of the mixture?
Answer: Fractional Distallation
Explanation: this technique relies on the compounds of the mixture. This is able to happen when there is diffrent boilling points.
which factors influence reaction rate? the more exothermic a reaction is, the faster the reaction rate.
The rate of a chemical reaction is influenced by many different factors, including reactant concentration, surface area, temperature, and catalysts.
Between exothermic or endothermic, exothermic reactions are said to be faster. This is primarily because in the exothermic process the reactions occur instantly or spontaneously. Here, no energy input is required to overcome any significant energy barriers..
About Chemical reactionChemical reactions are an integral part of technology, culture and human life. Smelting iron, making glass, brewing tea and making cheese are just a few examples of activities that combine chemical reactions that have been used for thousands of years. Chemical reactions are numerous in the earth, atmosphere and oceans.
Chemical reactions or chemical changes are all around us, from the metabolism of food in the body to how sunlight can be absorbed by the human body. There are two types of changes namely chemical changes and physical changes.
An example is a burning candle. Over time, the intact wax will turn into paraffin. The burning of a candle is a chemical reaction or chemical change, while the change of wax into paraffin is called a physical change.
Chemical reactions must be distinguished from physical changes. Physical changes include changes in state such as ice cubes melting into water, water evaporating into steam. If a physical change occurs, the physical properties of a substance will change but the chemical identity will remain the same.
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it is not possible to determine exactly when a particular unstable isotope will begin to decay. truefalse
The statement "It is not possible to determine exactly when a particularly unstable isotope will begin to decay" is true.
An isotope is a type of atom that possess different numbers of neutrons and protons. Depending on the excess or lack of neutrons, isotopes can be heavier or lighter.
Because most of the isotopes are unstable they mostly do not occur in nature. Isotopes are said to be stable if they do occur in nature. However, some unstable isotopes, such as Bismuth-209, are found in nature due to their long life span which can cover millions of years or more.
either more or fewer neutrons than protons are there in an unstable isotope. Unstable isotopes do not occur in nature for long periods because they eventually break up.
They emit energy in the form of electromagnetic waves or charged particles when they occur for a longer period in nature. The energy or particles released are called radiation.
They take either millions of years to break up or others just seconds. The isotopes which are more commonly found in heavy elements are unstable.
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