Problem: The hydrogen gas formed in a chemical reaction is collected over water at 30.0 oC at a total pressure of 734 mm Hg .If the total volume of gas collected is 724 mL , what mass of hydrogen gas is collected?

FREE Expert Solution

Dalton’s Law 
at 30.0°C, water has a vapor pressure of 31.8 mmHg


Ptotal=PGas 1+PGas 2+PGas 3...Ptotal=PH2+Pwater734 mmHg=PH2+31.8 mmHg-31.8 mmHg      -31.8 mmHg

PH2=702.2 mmHg


Ideal gas equation: moles H2


PVRT=nRTRTn=PVRT


mass = moles x molar mass

Molar mass of H2

H x 1.01 g/mol = 2.02 g/mol

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Problem Details

The hydrogen gas formed in a chemical reaction is collected over water at 30.0 oC at a total pressure of 734 mm Hg .

If the total volume of gas collected is 724 mL , what mass of hydrogen gas is collected?

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