Chem Unit 3-5 Test

Combined Gas Law

(P1V1)/T1 = (P2V2)/T2

oxidation of hydrogen

+1; -1 in binary compound with metals

London Forces

- found in all molecules, it's the instantaneous dipole moments created by the random movements/unequal distribution of electrons - more electrons means stronger LF - more spread out molecules = stronger IM forces

Dipole Dipole forces

- only in polar molecules - can attract to ionic compounds

oxidation of oxygen

-2; -1 in a peroxide

oxidation of elements

0

STP conditions

0 degrees Celsius and 1 atm

sum of oxidation numbers

0 or equal to the charge in a polyatomic ion

If 0.40 mol of H2 and 0.15 mol of O2 were to react completely as possible to produce H2O, what mass of reactant would remain?

0.20 g of H2

half lives of orders

0: [A]/2k 1: 0.693/k 2. 1/k[A] (use initial [A]

H3AsO4 + 3 I- + 2 H3O+ → H3AsO3 + I3- + H2O The oxidation of iodide ions by arsenic acid in acidic aqueous solution occurs according to the stoichiometry shown above. The experimental rate law of the reaction is: Rate = k[H3AsO4] [I-] [H3O+]

1

what conditions cause deviation from the ideal gas law

1. higher pressure: calculates a smaller volume calculation because higher pressures take up more volume. IGL molecules take up no volume 2. lower temperature: molecules have less energy to overcome the intermolecular forces. IGL doesn't take those into account

second order graphs

1. straight line plot when graphing 1/[A] vs. time 2. slope = k

zero order graphs

1. straight line plot when graphing [A} vs. t 2. slope = -k

first order graphs

1. straight line plot when graphing ln[A] vs. t 2. slope = -k

H2 + F2 -> 2HF In the reaction represented above, what mass of HF is produed by the reaction of 3.0 x 10^23 molecules of H2 with excess F2? (Assume the reaction goes to completion.)

20. g

The rate law for the reaction of nitrogen dioxide and chlorine is found to be rate = k [NO2]2[Cl2]. By what factor does the rate of the reaction change when the concentrations of both NO2 and Cl2 are doubled?

8

A student was studying physical and chemical changes. The student carried out some procedures in the laboratory and recorded observations. For one of the procedures, the student concluded that a physical change took place, but not a chemical change. Which of the following could have been the results of the procedure?

A cube of metal was changed into a flat sheet of metal.

C2H4)g) -> C2H6(g) What will most likely increase the rate of the reaction represented above?

Adding a heterogeneous catalyst to the reaction system

Which of the following best helps explain why an increase in temperature increases the rate of a chemical reaction?

At higher temperatures, high-energy collisions happen more frequently.

A kinetics experiment is set up to collect the gas that is generated when a sample of chalk, consisting primarily of solid CaCO3, is added to a solution of ethanoic acid, CH3COOH. The rate of reaction between CaCO3 and CH3COOH is determined by measuring the volume of gas generated at 25oC and 1 atm as a function of time. Which of the following experimental conditions is most likely to increase the rate of gas production?

Decreasing the particle size of the CaCO3 by grinding it into a fine powder

frequency / wavelength equations

E=hv, c = lambda/v; where h is plancks constant, v is frequency, c is the speed of light, and lambda is wavelength

oxidation of halogens

F: -1; others: -1 in a binary compound, sometimes positive otherwise

HCl + H2O --> H3O+ + Cl- For the dissolution of HCl in water represented above, which of the following pairs includes the Bronsted-Lowry bases?

H2O and Cl-

HCl(aq)+H2O(l)→H3O+(aq)+Cl−(aq) For the dissolution of HCl in water represented above, which of the following pairs includes the Brønsted-Lowry bases?

H2O(l) and Cl−(aq)

strong acids

HCl, HBr, HI, HNO3, H2SO4, HClO4

C2H4(g) + H2(g) −→(platinum) C2H6(g) C2H4(g) is reduced by H2(g) in the presence of a solid platinum catalyst, as represented by the equation above. Factors that could affect the rate of the reaction include which of the following? I. Changes in the partial pressure of H2(g) II. Changes in the particle size of the platinum catalyst III. Changes in the temperature of the reaction system

I, II, and III

Factors that affect the rate of a chemical reaction include which of the following? I. Frequency of collisions of reactant particles II. Kinetic energy of collisions of reactant particles III. Orientation of reactant particles during collisions

I, II, and III

HSO4- + H2O -> H3O+ + SO4(2-) In the equilibrium represented above, the species that act as bases include which of the following? I. HSO4- II. H2O III. SO4

II and III

C12H22O11(aq)+H2O(l)→2C6H12O6(aq) The chemical equation shown above represents the hydrolysis of sucrose. Under certain conditions, the rate is directly proportional to the concentration of sucrose. Which statement supports how a change in conditions can increase the rate of this reaction?

Increasing the concentration of sucrose will increase the rate of hydrolysis by increasing the frequency of the collisions between the sucrose and the water molecules.

strong bases

LiOH, NaOH, KOH, Ca(OH)2, Sr(OH)2, Ba(OH)2

When 0.20 M NH4Cl(aq) and 0.20 M NaOH(aq) are mixed, the reaction represented by the equation above occurs and a strong smell of ammonia, NH3, is observed. Based on this information, which of the following statements is true?

NH4+(aq) is a stronger acid than H2O(l) is.

arhenius base

OH- producer

Cu + 2AgNO3 --> Cu(NO3)2 + 2Ag The reaction between solid copper and aqueous silver nitrate produces solid silver and a blue solution, as represented by the balanced equation shown above. Based on the balanced equation, which of the following identifies the oxidation and reduction half-reactions?

Oxidation Half-Reaction = Cu -> Cu(2+) + 2e- Reduction Half-Reaction = Ag(+) + e- -> Ag

When C2H4 reacts with H2, the compound C2H6 is produced, as represented by the equation above. The reaction is correctly classified as what type? (See page 13 # 17)

Oxidation-reduction, because H2 is oxidized

When C2H4(g) reacts with H2(g), the compound C2H6(g) is produced, as represented by the equation above. The reaction is correctly classified as which of the following types?

Oxidation-reduction, because H2(g) is oxidized

I2 + C6H8O6 -> C6H6O6 + 2I- + 2H The compound C6H8O6 reacts with I2 according to the reaction represented by the equation above. The reaction correctly classified as which of the following types?

Oxidation-reduction, because I2 is reduced.

I2(aq)+C6H8O6(aq)→C6H6O6(aq)+2I−(aq)+2H+(aq) The compound C6H8O6 reacts with I2 according to the reaction represented by the equation above. The reaction is correctly classified as which of the following types?

Oxidation-reduction, because I2 is reduced.

Ideal Gas Law

PV=nRT

Equal volumes of 0.2 M solutions of lead(II) nitrate and postassium bromide are combined to form lead(II) bromide as a yellow precipitate. Which of the following is the correct net ionic equation for the reaction?

Pb(2+) + 2Br- -> PbBr2

Step 1. N2H2O2 ⇄ N2HO2- + H+ (fast equilibrium) Step 2. N2HO2- → N2O + OH- (slow) Step 3. H+ + OH- → H2O (fast) Nitramide, N2H2O2, decomposes slowly in aqueous solution. This decomposition is believed to occur according to the reaction mechanism above. The rate law for the decomposition of nitramide that is consistent with this mechanism is given by which of the following?

Rate = k[N2H2O2]/[H+]

experiment 1: x 0.10; y 0.30; rate 4.0 * 10^-4 experiment 2: x 0.20; y 0.60; rate 1.6* 10^-3 experiment 3: x 0.20; y 0.30; rate 4.0*10^-4 The data in the table above were obtained for the reaction X + Y → Z. Which of the following is the rate law for the reaction?

Rate: k[Y]2

Br2(g)+2NO(g)→2NOBr(g) The reaction represented by the equation above has the following proposed mechanism. Step 1:NO(g)+Br2(g)⇌NOBr2(g)(fast equilibrium) Step 2:NOBr2(g)+NO(g)→2NOBr(g)(slow) Based on the information, which of the following is the initial rate law for the reaction?

Rate=k[Br2][NO]2

Step 1:H2(g)+ICl(g)→HI(g)+HCl(g)(slow) Step 2:HI(g)+ICl(g)→HCl(g)+I2(g)(fast) Which of the following represents a rate law for the overall reaction that is consistent with the proposed mechanism?

Rate=k[H2][ICl]Rate=k[H2][ICl]

2H2(g)+2NO(g)→N2(g)+2H2O(g) For the chemical reaction represented above, the following mechanism is proposed. Step 1:2NO(g)⇌N2O2(g) (fast equilibrium) Step 2:N2O2(g)+H2(g)→N2O(g)+H2O(g) (slow) Step 3:N2O(g)+H2(g)→N2(g)+H2O(g) (fast) Which of the following initial rate law expressions is consistent with this proposed mechanism?

Rate=k[H2][NO]2Rate=k[H2][NO]2

Step 1:NO2(g)+F2(g)⇄NO2F2(g)(fast) Step 2:NO2F2(g)→NO2F(g)+F(g)(slow) Step 3:F(g)+NO2(g)→NO2F(g)(fast) A proposed mechanism for the chemical reaction 2NO2(g)+F2(g)→2NO2F(g)is shown above. Which of the following rate laws is consistent with this mechanism?

Rate=k[NO2][F2]

Step 1:2NO2(g)→NO3(g)+NO(g)(slow) Step 2:NO3(g)+CO(g)→NO2(g)+CO2(g)(fast) A proposed two-step mechanism for the chemical reaction NO2(g)+CO(g)→NO(g)+CO2(g) is shown above. Which of the following equations is a correct rate law that is consistent with the elementary steps in the mechanism?

Rate=k[NO2]^2

2NO(g)+Cl2(g)→2NOCl(g) The initial rates of the reaction represented by the equation shown above were measured for different initial concentrations of NO(g) and Cl2(g). Based on the data given in the table above, which of the following is the rate law expression for the reaction, and why?

Rate=k[NO]2[Cl2]Rate=k[NO]2[Cl2], because the initial rate quadrupled when [NO][NO] was doubled and doubled when [Cl2][Cl2] was doubled.

In what species does sulfur have the same oxidation number as it does in H2SO4?

SO2Cl2

An experiment was conducted to determine the rate law for the reaction A2(g)+B(g)→A2B(g). The table above shows the data collected. Based on the data in the table, which statement is correct?

Since the rate law can be expressed as rate=k[A2][B]rate=k[A2][B], doubling the concentrations of A2A2 and BB will quadruple the rate of the reaction.

Relatively slow rates of chemical reaction are associated with which of the following?

Strong bonds in reactant molecules

2F2+2NaOH->OF2+2NaF+H2O A 2 mol sample of F2 reacts with excess NaOH according to the equation above. If the reaction is repeated with excess NaOH but with 1 mol of F2, which of the following is correct?

The amount of OF2 produced is halved.

photoelectric effect

The emission of electrons from a metal when light shines on the metal

The gas-phase reaction A2(g)+B2(g)→2 AB(g) is assumed to occur in a single step. Two experiments were done at the same temperature inside rigid containers. The initial partial pressures of A2 and B2 used in experiment 1 were twice the initial pressures used in experiment 2. Which statement provides the best comparison of the initial rate of formation of AB in experiments 1 and 2 ?

The initial rate of formation of ABAB is faster in experiment 1 than in experiment 2 because at a higher pressure the collisions between A2 and B2 molecules would have been more frequent, increasing the probability of a successful collision.

Which of the following statements best explains why an increase in temperature of 5-10 Celsius degrees can substantially increase the rate of a chemical reaction?

The number of effective collisions between reactant particles is increased.

S2O82−(aq)+3I−(aq)→2SO42−(aq)+I3−(aq) In aqueous solution, the reaction represented by the balanced equation shown above has the experimentally determined rate law: rate=k[S2O82−][I−]. If the concentration of [S2O82−] is doubled while keeping [I−] constant, which of the following experimental results is predicted based on the rate law, and why?

The rate of reaction will double, because the rate is directly proportional to [S2O82−].

CH3I+NaOH→CH3OH+NaI The rate of the reaction represented by the chemical equation shown above is expressed as rate=k[CH3I][NaOH]. Based on this information, which of the following claims is correct?

The rate of the reaction will double if the concentration of CH3ICH3I is doubled while keeping the concentration of NaOHNaOH constant.

A student was asked to formulate a hypothesis about what would happen if 100 mL of 0.1 M NaOH at 25 *C was combined with 100 mL of 0.1 M MgCl2 at 25 *C. What hypothesis indicates that the student thought a chemical change would occur?

The resulting solution would precipitate

Which of the following best describes the role of the spark from the spark plug in an automobile engine?

The spark supplies some of the energy of activation for the combustion reaction.

NO(g) + NO3(g) → 2 NO2(g) rate = k[NO][NO3] The reaction represented above occurs in a single step that involves the collision between a particle of NO and a particle of NO3. A scientist correctly calculates the rate of collisions between NO and NO3 that have sufficient energy to overcome the activation energy. The observed reaction rate is only a small fraction of the calculated collision rate. Which of the following best explains the discrepancy?

The two reactant particles must collide with a particular orientation in order to react.

Zn(s)+2 HCl(aq)→ZnCl2(aq)+H2(g) Zn(s) reacts with HCl(aq) according to the equation shown above. In trial 1 of a kinetics experiment, a 5.0g piece of Zn(s) is added to 100mL of 0.10MHCl(aq). The rate of reaction between Zn(s) and HCl(aq) is determined by measuring the volume of H2(g) produced over time. In trial 2 of the experiment, 5.0g of powdered Zn(s) is added to 100mL of 0.10MHCl(aq). Which trial will have a faster initial rate of reaction and why?

Trial 2, because the sample of Zn(s)Zn(s) has a greater surface area for the reaction to take place.

See question 19

You're doing great!

*flip to the other side* 1. 2Ag + SO4 --> Ag2(SO4) 2. 3.79-0.88 = 2.91g. divide by 311.8 = 0.0093 3. 2(0.0093) = 0.0187. divide by .01 L = 1.87 M 4. the student did not let the sample fully dry out, as the decrease in mass after each 10 minute interval did not stabilize

answer the frq

*flip to the other side* 1. Ba^2+ + SO4^2- --> BaSO4 2. 1.136 - 0.764 = 0.372. divide by 233.4 = 0.0016 3. 1:1 ratio = 0.0016. divide by .05L = 0.032 M 4. m1v1 = m2v2. (.1)(v) = (50)(.5) = 0.025L 5. using a graduated cylinder, measure 25mL of the 0.1M CuSO4 solution and add to a 50mL volumetric flask. Dilute the solution with deionized water until the 50mL mark is reached. 6. 0.5/0.08 = 6.25

answer the frq

reaction rate equation

change in concentration/change in time

if you mix acid with carbonate

co2 is produced

collision theory

colliding atoms and molecules must of the correct orientation with a minimum energy greater than the activation energy to react

what does k represent

constant of proportionality; the rate constant

oxidation of monoatomic ions

equal to charge

Beer's Law

explains the relationship between absorbance, at a given wavelength and concentration, A = εbc

*flip to the other side* 1. first order 2. increase concentration of food coloring; the rate of a first order reaction is measured by k[A]. A greater concentration would increase the rate of reaction as it would take more time to react with the bleach 3. the spectrophotomer should be set to a different wavelength

finish the previous frq

*flip to the other side* 6. 0.5/0.08 = 6.25. 0.219 = 6.25x. x = 0.035 7. the concentration will be less than the CuSO4 solution. the addition of water would dilute the solution. there will also be decreased absorbance, resulted in a decreased calculated concentration.

finish the previous frq

rate constant

k = zfp, where z is collision frequency, f is the fraction of collisions with energy > Ea, and p is the fraction of collisions in the proper orientation

H2O2→H2O+1/2O2 Hydrogen peroxide decomposes to produce water and oxygen according to the equation above. An experimentally determined graph for the first-order decomposition of hydrogen peroxide is provided below. Which of the following best identifies the rate constant k for the reaction based on the information in the plot of ln[H2O2] versus time (t) ?

k=−(slope of plot)

The rate constant (k) for the decay of the radioactive isotope I-131 is 3.6×10−3 hours−1. The slope of which of the following graphs is correct for the decay and could be used to confirm the value of k ?

ln[I-131] vs time (negative slope)

The role of a catalyst in a chemical reaction is to

lower the activation energy for the reaction

if temperature increases

more collisions, more collisions with energy > Ea (affects this more)

peroxide

o2

arhenius acid

produces H+

Keq < 1

product favored

bronsted-lowry base

proton (H+) acceptor

Bronsted-Lowry acid

proton (H+) donor

elementary step: A A + A A + B A + A + A A + A + B A + B + C find the rate law

r = k[A] r = k[A]^2 r = [A][B] r = [A]^3 r = [A]^2[B] r = [A][B][C]

rate law

r = k[A]^n, where n is the rate order

first order

rate is directly proportional to concentration; r = k[A]

zero order

rate is independent of concentration; rate = k

second order

rate is proportional to the square of the concentration; r = k[A]^2

Keq > 1

reactant favored

rate determining step

slow step

weak acid has ______ conjugate base; strong acid has _____ conjugate bas; vice versa for bases

strong; weak

2 A(g) + B(g) → 2 C(g) When the concentration of substance B in the reaction above is doubled, all other factors being held constant, it is found that the rate of the reaction remains unchanged. The most probable explanation for this observation is that

substance B is not involved in the rate-determined step of the mechanism, but is involved in subsequent steps

redox reaction

transfer of electrons from one reactant to another; oxidation-reduction reaction.

When the actual gas volume is greater than the volume predicted by the ideal gas law, it's because ideal gas law does NOT include a factor for molecular

volume