Test 3 Study Guide

586

The root-mean-square speed of CO at 113°C is __________ m/s A)993 B)31.5 C)58.3 D)317 E)586

endothermic positive

A chemical reaction that absorbs heat from the surroundings is said to be _____________ and has a __________∆H at constant pressure. A)exothermic, neutral B)exothermic, negative C)exothermic, positive D)endothermic, negative E)endothermic, positive

its behavior is described by the ideal-gas equation

A gas is considered "ideal" if _____________ A)one mole of it occupies exactly 1 liter at standard temperature and pressure B)its behavior is described by the ideal-gas equation C)it can be shown to occupy zero volume at 0°C D)one mole of it in a one-liter container exerts a pressure of exactly 1 atm at room temperature E)it is not compressible

16.0

A sample of gas (24.2g) initially at 4.00 atm was compressed from 8.00 L to 2.00 L at constant temperature. After the compression, the gas was _________ atm. A)2.00 B)16.0 C)1.00 D)8.00 E)4.00

239

A vessel contained N₂, At, He, and Ne. The total pressure in the vessel was 987 torr. The partial pressures of nitrogen, argon, and helium were 44, 486, and 218 torr, respectively. The partial pressure of neon in the vessel was ___________torr. A)42.4 B)239 C)19.4 D)521 E)760

average kinetic energy

According to the kinetic-molecular theory, molecules of different gases at the same temperature always have the same ___________ A)average kinetic energy B)average density C)volume D)molecular mass E)pressure

have no attraction for one another

An ideal gas differs from a real gas in that the molecules of an ideal gas ____________. A)have an average molecular mass B)have appreciable molecular volumes C)have a molecular weight of zero D)have no attraction for one another E)have no kinetic energy

CO₂ < O₂ < N₂< He

Arrange the following gases in order of increasing average molecular speed at 25°C: He, O₂, CO₂, N₂ A) CO₂ < He < N₂ < O₂ B) CO₂ < N₂ < O₂ < He C) He < N₂ < O₂ < CO₂ D) CO₂ < O₂ < N₂ < He E) He < O₂ < N₂ < CO₂

both Co(s) and H₂(g)

For the species in the reaction below, ∆Hf° is zero for___________. 2Co(s) + H₂(g) + 8PF₃(g) → 2HCo(PF₃)₄(l) A)HCo(PF₃)₄(l) B)H₂(g) C)PF₃(g) D)Co(s) E)both Co(s) and H₂(g)

(1/2)N₂(g) + O₂(g) → NO₂(g)

For which one of the following reactions is ∆H°rxn equal to the heat of formation of the product? A) 6C(s) + 6H(g) → C₆H₆(l) B) (1/2)N₂(g) + O₂(g) → NO₂(g) C) P(g) + 4H(g) + Br(g) → PH₄Br(l) D) N₂(g) + 3H₂(g) → 2NH₃(g) E) 12C(g) + 11H₂(g) + 11O(g) → C₆H22O11(g)

570.37

Given the data below, ∆H°rxn for the reaction PCl₃(g) + 3HCl(g) → 3Cl₂(g) + PH₃(g) PCl₃(g) ---> -288.07 kJ/mol HCl(g) ---> -92.30 kJ/mol PH₃(g) ---> 5.4 kJ/mol is ___________ kJ A)385.77 B)570.37 C)-570.37 D)-385.77 E)The ∆H°f of Cl₂(g) is needed for the calculation

-293.8

Given the following reactions N2(g) + O2(g) --> 2NO(g) ∆H= +180.7 kJ 2NO(g) + O2(g) --> 2NO2(g) ∆H= -113.1 kJ the enthalpy of reaction for 4NO(g) --> 2NO2(g) + N2(g) is _________kJ A)45.5 B)293.8 C)-45.5 D)67.6 E)-293.8

CH₄

Of the following gases, ____________ will have the greatest rate of effusion at a given temperature A)NH₃ B) HBr C) Ar D) HCl E) CH₄

PV= constant

Of the following, _____________ is a correct statement of Boyle's law A) V/P= constant B) V/T= constant C) P/V= constant D) n/P= constant E) PV= constant

273 K and 1 atm

Standard temperature and pressure (STP), in the context of gases, refers to ___________. A)273 K and 1 pascal B)298 K and 1 atm C)298 K and 1 torr D)273 K and 1 atm E)273 K and 1 torr

1.18

The amount of gas that occupies 60.82 L at 31°C and 37 mmHg is ____________mol. A)0.120 B)0.850 C)894 D)11.6 E)1.18

both the gas molecules collide more frequently with the wall and the gas molecules collide more energetically with the wall

The kinetic-molecular theory predicts that pressure rises as the temperature of a gas increases because ___________ A)the average kinetic energy of the gas molecules decreases B)the gas molecules collide less frequently with the wall C)the gas molecules collide more frequently with the wall D)the gas molecules collide more energetically with the wall E)both the gas molecules collide more frequently with the wall and the gas molecules collide more energetically with the wall

129

The molar mass of a gas that has a density of 5.75g/L at STP is ________________g/mol. A)1.73x10⁻³ B)141 C)578 D)3.90 E)129

20.2

The value of ∆H° for the reaction below is -126 kJ. The amount of heat that is released by the reaction of 25.0 g of Na₂O₂ with water is _________ kJ. 2Na₂O₂(s) + 2H₂O(l) → 4NaOH(s) + O₂(g) A)20.2 B)40.4 C)-126 D)67.5 E)80.8

all of the above statements are true

The van der Waals equation for real gases recognizes that __________________. A)the molecular attractions b/w particles of gas decreases the pressure exerted by the gas B)molar volumes of gases of different types are different C)the non-zero volumes of gas particles effectively decrease the amount of "empty space" b/w them D)gas particles have non-zero volumes and interact w/ each other E)all of the above statements are true

If a reaction is carried out in a series of steps, the ∆H for the reaction will equal the sum of the enthalpy changes for the individual steps

Which of the following is a statement of Hess's law? A)the ∆H for a process in the forward direction is equal in magnitude and opposite in sign to the ∆H for the process in the reverse direction B)the ∆H of a reaction depends on the physical states of the reactants and products C)If a reaction is carried out in a series of steps, the ∆H for the reaction will equal the sum of the enthalpy changes for the individual steps D)If a reaction is carried out in a series of steps, the ∆H for the reaction will equal the product of the enthalpy changes for the individual steps E)the ∆H for a process in the forward direction is equal to the ∆H for the process in the reverse direction

freezing of water

Which of the following is an exothermic process? A)when a certain salt is dissolved in water the temperature of the water drops B)water evaporating C)sublimation of carbon dioxide D)ice melting E)freezing of water

the system gains heat and has work done on it by the surroundings

Which one of the following conditions would always result in an increase in the internal energy of a system? A)the system gains heat and has work done on it by the surroundings B)the system gains heat and does work on the surroundings C)the system loses heat and does work on the surroundings D)the system loses heat and has work done on it by the surroundings E)none of the above is correct

V= constant x n

Which one of the following is a valid statement of Avogadro's law? A)V= constant x P B)V/T= constant C)P/T= constant D)PV= constant E)V= constant x n

enthalpy is a state function

Which one of the following statements is true? A)the enthalpy change for a reaction is independent of the state of the reactants and products B)the enthalpy change of a reaction is the reciprocal of the ∆H of the reverse reaction C)enthalpy is a state function D)H is the value of q measured under conditions of constant volume E)enthalpy is an intensive property