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 data:

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

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