3. A volume of 546 mL of hydrogen is collected over water at 30 degrees * C when the atmospheric pressure is 100.45 kPa. How many moles of hydrogen are present?

Number of moles of hydrogen are 0.022 mol.

Explanation:

Given dа ta:

Volume of hydrogen = 546 mL

Temperature = 30°C

Pressure = 100.45 kpa

Number of moles of hydrogen = ?

Solution:

According to ideal gas equation,

PV = nRT

P = pressure

V = volume

n = number of moles

R = ideal gas constant

T = temperature

First of all we will convert the units,

Temperature = 30 + 273 = 303 K

Pressure = 100.45 / 101 = 0.99 atm

Volume of hydrogen = 546 mL * 1L / 1000 mL = 0.546 L

Now we will put the values in formula,

PV = nRT

n = PV/RT

n = 0.99 atm * 0.546 L / 0.0821 atm. L/mol. K * 303 K

n = 0.541 atm. L / 24.876 atm. L / mol

n = 0.022 mol