Chem 120 Midterm 1 Questions with
complete solution 2025
Properties of gases - correct answer ✔- fill and assume shape of container
- diffuse and mix in all proportions with other gases
- molecules in gas are separated by large distances and interact weakly with
each other
Variables that describe any gas - correct answer ✔- nb of moles
- temperature
- pressure
- volume
Pressure - correct answer ✔- In Pa
- Force (N)/Area (m^2) - force per unit area
- Force = area x height x density x force of gravity
- So pressure = Height x density x force of gravity
Atmospheric pressure - correct answer ✔760 mmHg
760 torr
1 atm
101325 Pa
Manometer - correct answer ✔- measure pressure of confined volume of gas
- P(gas) = P(bar) when height of Hg is equal on both sides
- when P(gas) > P(bar), P(gas)= P(bar) + change in P
,- when P(gas) < P(bar), P(gas)= P(bar) - change in P
Ratio of heights (h) - correct answer ✔- inversely related to the ratio of the
densities of the liquid (d)
h (H2O)/ h (Hg) = d(Hg)/d(H2O)
Boyle's law - correct answer ✔- volume is inversely proportional to pressure
- PV = constant
- V1P1 = V2P2
Charle's law - correct answer ✔- low temp = small volume
- high temp = large volume
- V/T = constant
- V1/T1 = V2/T2
Avogadro's law - correct answer ✔- equal vol of any ideal gas contain same
nb of molecules
- equal nb of molecules occupy equal volumes
- volumes are proportional to coefficients in chemical equation
STP - correct answer ✔- temp = 273.15 K
- pressure = 1 bar = 0.9869 atm
- 1 mol (6.02 x 10^23)
- Volume = 22.7 L
ideal gas equation - correct answer ✔PV = nRT
, General gas equation - correct answer ✔P1V1/n1T1 = P2V2/n2T2
Molar mass of a gas - correct answer ✔n = m/M
PV = mRT/M
M = mRT/PV
m= MPV/RT
Gas density - correct answer ✔d = m/V
d= MP/RT
- proportional to molecular weight
- depends on pressure and temperature
- double pressure = double density
- double temperature = half of density
Gay-Lussac's law - correct answer ✔- gases react in volumes proportional to
small whole numbers
Dalton's law of partial pressures - correct answer ✔- the total pressure
exerted by a gaseous mixture is equal to the sum of partial pressures of each
individual component in a gas mixture
- P(tot) = n(tot) RT/V
Newton's laws of motion - correct answer ✔- particles in random straight-
lone motion
- separated by large distances so brief collisions
- no long range forces
complete solution 2025
Properties of gases - correct answer ✔- fill and assume shape of container
- diffuse and mix in all proportions with other gases
- molecules in gas are separated by large distances and interact weakly with
each other
Variables that describe any gas - correct answer ✔- nb of moles
- temperature
- pressure
- volume
Pressure - correct answer ✔- In Pa
- Force (N)/Area (m^2) - force per unit area
- Force = area x height x density x force of gravity
- So pressure = Height x density x force of gravity
Atmospheric pressure - correct answer ✔760 mmHg
760 torr
1 atm
101325 Pa
Manometer - correct answer ✔- measure pressure of confined volume of gas
- P(gas) = P(bar) when height of Hg is equal on both sides
- when P(gas) > P(bar), P(gas)= P(bar) + change in P
,- when P(gas) < P(bar), P(gas)= P(bar) - change in P
Ratio of heights (h) - correct answer ✔- inversely related to the ratio of the
densities of the liquid (d)
h (H2O)/ h (Hg) = d(Hg)/d(H2O)
Boyle's law - correct answer ✔- volume is inversely proportional to pressure
- PV = constant
- V1P1 = V2P2
Charle's law - correct answer ✔- low temp = small volume
- high temp = large volume
- V/T = constant
- V1/T1 = V2/T2
Avogadro's law - correct answer ✔- equal vol of any ideal gas contain same
nb of molecules
- equal nb of molecules occupy equal volumes
- volumes are proportional to coefficients in chemical equation
STP - correct answer ✔- temp = 273.15 K
- pressure = 1 bar = 0.9869 atm
- 1 mol (6.02 x 10^23)
- Volume = 22.7 L
ideal gas equation - correct answer ✔PV = nRT
, General gas equation - correct answer ✔P1V1/n1T1 = P2V2/n2T2
Molar mass of a gas - correct answer ✔n = m/M
PV = mRT/M
M = mRT/PV
m= MPV/RT
Gas density - correct answer ✔d = m/V
d= MP/RT
- proportional to molecular weight
- depends on pressure and temperature
- double pressure = double density
- double temperature = half of density
Gay-Lussac's law - correct answer ✔- gases react in volumes proportional to
small whole numbers
Dalton's law of partial pressures - correct answer ✔- the total pressure
exerted by a gaseous mixture is equal to the sum of partial pressures of each
individual component in a gas mixture
- P(tot) = n(tot) RT/V
Newton's laws of motion - correct answer ✔- particles in random straight-
lone motion
- separated by large distances so brief collisions
- no long range forces
