Phychem

Question 1

What is the most ideal gas?

Answer 1

Helium

Question 2

For all spontaneously occurring processes in an isolated system, which expression best describes dS?

Answer 2

infinitesimal change in entropy of a system
dS>0

Question 3

Equation of state for a single component can be any of the following except

Answer 3

a mathematical expression defining a path between states

Question 4

Colligative properties are properties that _____

Answer 4

depend upon the concentration of solute molecules or ions, but not upon the identity of the solute.

or depend on the amount of solute and nature or solvent

Question 5

The system CaCO3:CaO:CO2 has components, phases, variances

Answer 5

2,3,1

(Use F = C - P + 2
C = number of independent components
P = number of phases
S = number of actual chemical species
if no chemical reaction C=S
if there is a chemical reaction C = S minus no. of reaction

Question 6

Which of the following is true about the dissolution process?

Answer 6

the enthalpy of solution is temperature dependent

Question 7

The Ka1 of phosphoric acid is 0.0086 and ΔH = -14.2 kJ/mol at 25°C. What is the Ka at 60°C?

Answer 7

4.71 x 10^-3

Question 8

Liquids 2-pentanone and 3-pentanone are present in 2:5 ratio at equilibrium. What is the pressure (mmHg) of the solution and fraction of 3-pentanone in the vapour phase at
25°C?

Answer 8

0.724

Question 9

What is the partial pressure (torr) of methane in a 200-g mixture of methane and argon (39.96 g/mol) if it is found that argon is 10% by mass and the total pressure is 250 torr?

Answer 9

239.25 torr

Question 10

At what altitude will the pressure of air (28.8 g/mol) be one-fourth of tis pressure at sea level? Assume that temperature does not change at 28°C.

Answer 10

1229 m
12.29 km

Use: P=Poe^(-Mgz/RT)

Question 11

What is the most probable identity of the gas in a liter of a 350-gram container at 30°C and exerts 0.76 atm? The mass of the container with gas is 254 g.

Answer 11

Xenon

Question 12

What is the partial pressure (torr) of methane in a 200-g mixture of methane and argon if it is found that argon is 10% by mass and the total pressure is 350 torr?

Answer 12

334.95 torr

Question 13

Consider moist air at SATP and 75% relative humidity. What is the mole fraction of water vapour?

Answer 13

0.023

Question 14

Consider moist air at SATP and 75% relative humidity. What is the molar mass of moist air?

Answer 14

28.747 g/mol

Question 15

What is the value of the Joule-Thomson coefficient (deg/atm) given the following data?

Answer 15

3.5

Use: ∆T=uJT∆P + 0
solve for slope = B in calc = uJT