1) A sample of hydrogen was collected by water displacement at 23.0°C and an
atmospheric pressure of 735 mmHg. Its volume is 568 mL. After water vapor is
removed, what volume would the hydrogen occupy at the same conditions of pressure
and temperature? (The vapor pressure of water at 23.0°C is 21 mmHg.)

2) The metal potassium crystallizes in a body-centered cubic lattice. If the density of
potassium is 0.856 g/cm3, what is the unit cell volume?

3) A metal crystallizes in a face-centered cubic lattice. The radius of the atom is 214 pm
and the density of the element is 2.63 g/cm3. What is the identity of the metal?

4)A particular compound has an enthalpy of vaporization of 28800 J/mol. At 276 K it has
a vapor pressure of 103 mmHg. What is its vapor pressure at 307 K? (R = 8.31 J/(K·
mol))

i figured out number 4 so i dont that one explained anymore

1) A sample of hydrogen was collected by water displacement at 23.0°C and an
atmospheric pressure of 735 mmHg. Its volume is 568 mL. After water vapor is
removed, what volume would the hydrogen occupy at the same conditions of pressure
and temperature? (The vapor pressure of water at 23.0°C is 21 mmHg.)


Now total pressure exerted by water vapor and hydrogen gas = 735 + 21 = 756atm
P1V1=P2V2(dry H2 gas)
V2 = P1V1/P2 = 756atm  X 568 mL/735 mmHg

2) The metal potassium crystallizes in a body-centered cubic lattice. If the density of
potassium is 0.856 g/cm3, what is the unit cell volume?


density = mass / volume
now it is bcc type of unit cell
No of atoms per unit cell = 2
mass of two K atoms =  2X 40 g/ 6.022 X 10^ 23
volume =  mass / density = 2X 40 g/ 6.022 X 10^ 23  / 0.856 g/cm3

4)A particular compound has an enthalpy of vaporization of 28800 J/mol. At 276 K it has
a vapor pressure of 103 mmHg. What is its vapor pressure at 307 K? (R = 8.31 J/(K·
mol)

The Clausius–Clapeyron equation

ln(P1/P2) = Delta Hvap/R(1/T2- 1/T1)
lnP1-lnP2=Delta Hvap/R(1/T2- 1/T1)

where

T1 and P1 are a corresponding temperature (in kelvin or other absolute temperature units) and vapor pressure
T1= 276 K
P1=103 mmHg= 103/760  atm
T2 and P2 are the corresponding temperature and pressure at another point
T2 = 307K
P2=?
Inow you can plug in all values in the given equation to get P2
ΔHvap is the molar enthalpy of vaporization=28800 J/mol
R is the gas constant (8.314 J mol−1K−1)