Question

In an experiment, a student collects 107 mL of H2 over water at a pressure of 104.8 kPa and a temperature of 30°C. How many grams of H2 are present?

A) 0.024 g
B) 4.00 g
C) 0.04 g
D) 0 049 g
And why

Answer 1

The answer options provided are incorrect. The correct answer is 0.009g

Step-by-step explanation:

Using PV = nRT

Where;

P = pressure (atm)

V = volume (L)

R = gas constant (0.0821 Latm/Kmol)

T = temperature (K)

n = number of moles

Based in the information provided;

V = 107mL = 107/1000 = 0.107L

P = 104.8kPa = 104800 Pa = 1.03atm

T = 30°C + 273.15 = 303.15K

PV = nRT

1.03 × 0.107 = n × 0.0821 × 303.15

0.1102 = 24.89n

n = 0.1102/24.89

n = 0.0044 mol

mole = mass/molar mass

Molar mass of H2 = 2g/mol

mass = molar mass × mole

mass = 2 × 0.0044

mass = 0.0088

mass = 0.009g