CHEM 161- Mastering Chemistry

A balloon is filled under the initial conditions indicated below. If the pressure is then increased to 2 atmatm while the temperature is increased to 50 ∘C∘C, which balloon on the right, (a) or (b), represents the new volume of the balloon?

(a)

The enthalpy for the formation of 1 mole of NH3(aq)NH3(aq) is -80.29 kJ/molkJ/mol. What is the enthapy for the formation of 3 moles of NH3(aq)NH3(aq)?

-240.87 kJ

Convert the blood pressure 150/110 from mmHgmmHg to inHginHg. Assume that the ambient barometric pressure is 30 inHginHg. How do they compare?

150, 110 = 5.91,4.33 inHg 0.197

Consider the reaction shown: 304.0 kcal + 4 PCl3 (l) → P4 (s) + 6 Cl2 (g) When 50.00 g of PCl3 react, ________ kcal will be

27.67; consumed

How many Calories (that is, kilocalories) are in a 53.3 gg serving of potato chips if we assume that they are essentially 50% carbohydrate, and 50% fats? [Energy from Food, p. 185 in the textbook]

346 kcal

What is the heat absorbed in kcalkcal and kJkJ when 2.50 moles of NONO are produced from oxygen and nitrogen? N2(g)+O2(g)→2NO(g)N2(g)+O2(g)→2NO(g) ΔHΔH = +43.0 kcal/molO2kcal/molO2 or +180 kJ/molO2kJ/molO2.

54 kcalkcal, 230 kJ

The atmospheric pressure on the top of MtMt. Everest, an altitude of 29,035 ftft, is only 265 mmmm HgHg. What is the partial pressure of oxygen in the lungs at this altitude (assuming that the % O2O2 is the same as in dry air)?

55.1 mmHg

Consider this combination reaction: 2Mg(s)+O2(g)→2MgO(s) ΔH=−1204 kJ2Mg(s)+O2(g)→2MgO(s) ΔH=−1204 kJ What is the enthalpy for the decomposition of 1 mole of MgO(s)MgO(s) into Mg(s)Mg(s) and O2(g)O2(g)?

602 kJ/mol

Assuming a total pressure of 9.2 atm, what is the partial pressure of helium in the mixture of 98%% helium and 2.0%% oxygen breathed by deep-sea divers? What is the partial pressure of oxygen in the mixture? How does the partial pressure of oxygen in diving gas compare with its partial pressure in normal air?

9.0 atm 0.18 atm The partial pressures are approximately equal.

London dispersion forces

All molecules exhibit London forces, which increase in strength with increasing molecular weight.

Which molecule would have the highest boiling point?

CH3FCH3F

Dipole-dipole forces

Dipole-dipole interactions are important for molecules that are polar.

Hydrogen bonding

Hydrogen bonding occurs between an unshared electron pair on an electronegative atom (OO, NN, or FF) and a hydrogen atom bonded to a second electronegative atom (OO, NN, FF).

Which of the following actions will cause the equilibrium to shift such that the concentration of NONO gas will increase? 2NO(g) + 2H2(g) ⇌ N2(g)+2H2O+heat

Increase the concentration of H2O(g)

Which statement best describes the way a catalyst works? It increases the value of ΔH.I t increases the value of ΔG. It decreases the value of Eact. It increases the value of Eact. It decreases the value of ΔH.

It decreases the value of Eact.

Identify the intermolecular forces that influence the properties of CH4CH4 (methane).

London dispersion

Identify the intermolecular forces that influence the properties of CH3FCH3F (fluoromethane).

London dispersion Dipole-dipole

Which of the following statements regarding Bond Dissociation Energy is correct?

Molecules with strong covalent bonds will have large bond dissociation energy values.

Which equilibrium reaction will experience a shift towards the products in equilibrium position when the concentration of Ni2+Ni2+ is increased?

Ni2+(aq)+6NH3(aq)⇌[Ni(NH3)6]2+

Consider the exothermic reaction Fe2O3(s)+2Al(s)⇌Al2O3(s)+2Fe(s)Fe2O3(s)+2Al(s)⇌Al2O3(s)+2Fe(s) In what direction will the equilibrium shift when heat is removed?

The equilibrium will shift toward the products.

Show the approximate level of the movable piston in drawing (b) after the indicated changes have been made to the initial gas sample (assume a constant pressure of 1 atm)

The final volume is a bit less than the original volume.

Show the approximate level of the movable piston in drawing (a) after the indicated changes have been made to the initial gas sample (assume a constant pressure of 1 atm)

The final volume is the same as the original volume.

When HCl(aq)HCl(aq) and NaOH(aq)NaOH(aq) are mixed in a beaker, the beaker feels warm to the touch. What is known about the enthalpy of this reaction?

The reaction is exothermic.

When this reaction in equilibrium is heated, a red/brown color persists. What is true about this reaction? 2NO2(g)brown/red⇋N2O4(g)colorless

The reaction is exothermic.

If the reaction N2(g)+3H2(g)⇌2NH3(g)N2(g)+3H2(g)⇌2NH3(g) is at equilibrium, what direction will the reaction shift if NH3NH3 gas is added?

The reaction will shift to produce reactants.

If an endothermic reaction is at equilibrium, how will the equilibrium shift when heat is added to the reaction?

The reaction will shift toward the products.

Consider the reaction 2H2(g)+O2(g)⇌2H2O(g)2H2(g)+O2(g)⇌2H2O(g) How will the equilibrium shift when hydrogen gas is removed?

The system will shift toward the reactants.

Based on the reaction shown, which statement is true?P4 (s) + 10 Cl2 (g) → 4 PCl5 (s) ΔH = -435.2 kcal

When 1 mol P4 (s) reacts, 435.2 kcal are released.

Which of the following states of matter should have the lowest entropy value?

a crystalline solid

Which of the following states of matter generally has the lowest entropy? a. a crystalline solid b. a liquid c. a gas d. two of the three have virtually the same entropy

a. a crystalline solid

Which is assumed to be true in most explanations of how reactions occur? a. reactant particles must collide with each other b. catalysts must be present c. energy must be absorbed as the reaction proceeds d. more than one response is correct

a. reactant particles must collide with each other

If the reaction A + B C occurs and pure A and B were mixed, which of the following would take place as equilibrium was established? a. The concentration of C would increase for a time, then remain constant. b. The concentration of A would increase for a time, then decrease. c. The concentration of B would increase for a time, then remain constant. d. More than one response is correct.

a. the concentration of C would increase for a time, then remain constant

Which of the following is an endergonic process? a. exothermic reactions b. endothermic reactions c. equilibrium reactions d. proposed reactions that do not proceed

b. endothermic reactions

At 20°C, a sample of solid spontaneously sublimes to a gas. This change in state is accompanied by which of the following changes in the solid sample? a. entropy & energy decrease b. entropy & energy increase c. entropy decreases & energy increases d. energy decreases & entropy increases

b. entropy & energy increase

In an exergonic process, the system a. gains energy b. loses energy c. neither gains nor loses energy d. more than one response is correct

b. loses energy

Homogeneous catalysts are thought to function by a. raising the temperature b. lowering activation energy of a reaction c. removing a reacting molecule d. more than one response is correct

b. lowering activation energy of a reaction

Which is an incorrect statement when discussing molecular collisions leading to the chemical reaction,AB + CD → AD + CB? a. The faster the motion of the molecules, the more likely they are to collide. b. The faster the motion of the molecules, the greater the probability that a chemical reaction will occur. c. The slower the motion of the molecules, the more likely that this reaction will become an equilibrium reaction favoring the left side of the equation. d. The relationship between molecular collisions and reaction rate is direct.

c. The slower the motion of the molecules, the more likely that this reaction will become an equilibrium reaction favoring the left side of the equation.

Equilibrium:The following question(s) refer to the following equilibrium in which all reactants and products are gases:CH4 + H2O CH3OH + H2 + heatIndicate the effect of the changing condition on the position of equilibrium.Refer to Equilibrium. Add a catalyst to the mixture. a. shifts left b. shifts right c. no effect d. can shift to right or left

c. no effect

The reaction conditions for a specific reaction, BCD + HA ⇔ ABCDH, are correct, but the reaction does not occur. What could be the reason? a. There are no collisions between the molecules. b. The collisions of the particles with the container walls removes the required energy because it is transferred to the container molecules. c. The orientation of the molecules with respect to each other is not correct for the reaction to occur. d. There is more than one answer.

c. the orientation of the molecules with respect to each other is not correct for the reaction to occur.

In a system of equilibrium, it is true that a. the rate of the forward reaction exceeds that of the reverse b. the rate of the forward reaction is lower than that of the reverse reaction c. the rate of the forward reaction is equal to the rate of the reverse reaction d. more than one response is correct.

c. the rate of the forward reaction is equal to the rate of the reverse reaction

Which of the following is most closely related to the term "reaction rate"? a. the temperature needed to initiate a reaction b. the position of equilibrium when a reaction stops c. the speed of a reaction d. more than one response is correct

c. the speed of a reaction

Which of the following processes represents an exothermic change?

condensation

A reaction which is unfavorable with respect to entropy, but favorable with respect to enthalpy

could occur at low temperatures but not at higher temperatures.

Which of the following statements about a K of 3.5 calculated for a specific chemical reaction at equilibrium is incorrect? a. It was calculated by dividing the product of the products by that of the reactants. b. It indicates that one side of the reaction has most of the matter present. c. It is an evaluation of the extent of the two chemical reactions involved: the forward and the reverse reactions. d. A K of 3.5 indicates that a catalyst will push the reaction to the right.

d. A K of 3.5 indicates that a catalyst will push the reaction to the right.

Which of the following will influence all reaction rates? a. the presence of catalysts b. the temperature of reactants c. the concentration of reactants d. more than one response is correct

d. more than one response is correct

the reaction A + B → AB, which of the following will not increase the rate?

decreasing the temperature

A process or reaction which takes in heat from the surroundings is said to be

endothermic.

The energy diagram shown represents the chemical reaction between solid ammonium chloride and solid barium hydroxide octahydrate: 2NH4Cl(s)+Ba(OH)2⋅8H2O(s)→2NH3(aq)+BaCl2(aq)+10H2O(l)2NH4Cl(s)+Ba(OH)2⋅8H2O(s)→2NH3(aq)+BaCl2(aq)+10H2O(l) The ΔHΔHDelta H for this reaction is 54.8 kJkJ . How much energy would be absorbed if 27.9 gg of NH4ClNH4Cl reacts?

energy absorbed = 14.3 kJkJ

The concept of free energy allows prediction of spontaneity of a process by considering the changes in ________ and ________ during the process.

enthalpy; entropy

A reaction is said to be ________ if the bonds formed during the reaction are stronger than the bonds broken.

exothermic

2 CO (g) + O2 (g) → CO2 (g) + 135.2 kcalThis reaction is ________ because the sign of ΔH is

exothermic; negative

A rapid reaction is distinguished by

having a small value of activation energy.

To simplify comparisons, the energy value of fuels is expressed in units of

kcal/g.

In the process of rust formation, ΔG is negative because it is stated that the process is spontaneous. Since rust formation is slow Eact is large.

negative, slow, large

The scientific principle which explains the observation that the amount of heat transfer accompanying a change in one direction is numerically equal but opposite in sign to the amount of heat transfer in the opposite direction is

the Law of Conservation of Energy.

Estimate ΔHΔH for the reaction using bond dissociation energies from Table 7.1. Give your answer in kcal/molkcal/mol and kJ/molkJ/mol. C6H12O6C6H12O6 has five C−CC−C bonds, seven C−HC−H bonds, seven C−OC−O bonds, and five O−HO−H bonds. Is the reaction exothermic or endothermic?

ΔHΔH = 652,2730 kcal/molkcal/mol, kJ/molkJ/mol endothermic

The following diagram portrays a reaction of the type A(s)→B(s)+C(g)A(s)→B(s)+C(g), where the different colored spheres represent different molecular structures. Assume that the reaction has ΔH=−23.5ΔH=−23.5 kcal/molkcal/mol. What is the sign of ΔSΔS for the reaction? Is the reaction likely to be spontaneous at all temperatures, nonspontaneous at all temperatures, or spontaneous at some but nonspontaneous at others?

ΔS>0 spontaneous at all temperatures