Equations

Question 1

Standard temp and pressure

Answer 1

0ºC (273.15 K) and 1 atm

Question 2

Standard conditions

Answer 2

25ºC (298.15 K)

Question 3

Boyle’s Law

Answer 3

pressure is inversely proportional to volume @ constant temp

P₁V₁=P₂V₂

*as pressure increases volume decreases @ constant temp (isothermal)

Question 4

Charles Law

Answer 4

Volume is directly proportional to temperature @ constant pressure

V₁ / T₁ = V₂ / T₂

Question 5

Combined Gas Law

Answer 5

P₁V₁ / T₁ = P₂V₂ / T₂

Question 6

Avagadro’s law of Molar Volume

Answer 6

n (number of moles) is directly proportional to volume (V)

n₁ / V₁ = n₂ / V₂

if gases at equal volumes have the same pressure and temp, are equal in number of moles/particles/molecules

Question 7

Under STP conditions ( 0C, 1 atm) 1 mole of any gas shall…

Answer 7

have a volume of 22.4 Liters

1 mole = 22.4 L @ STP

if gases at equal volumes have the same pressure and temp, are equal in number of moles/particles/molecules

Question 8

Ideal gas law

Answer 8

PV = nRT

R= 0.0823 atm • L/ mol•K

Question 9

molecular mass from ideal gas law

Answer 9

Molecular mass = nRT / PV = g / mol

(p) density = P • m_r / RT = g / liters

Question 10

Dalton’s law

Answer 10

P_total = P_A + P_B + P_C

PV=nRT, therefore

P_T = n_A (RT/V) + n_B (RT/V) +…

= n_A + n_B + n_C (RT/V)

= n_total(RT/V)

Question 11

mole fraction (X_a)

Answer 11

X_A = n_A / n_A + n_B + n_C = n_A / n_total

P_A = X_A • P_T

Question 12

graham’s law of effusion

Answer 12

rate of effusion of gas A / rate of effusion of gas B = ( m_r of gas B)^1/2/ (mr of gas A)^1/2