# A 30.9mL sample of H2 at STP would contain how many grams of hydrogen?

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- hcbiochemLv 71 decade agoBest Answer
Divide 0.0309 L by 22.4 L/mol to get the moles of gas in the sample. Then use the molar mass of H2 to calculate the mass:

0.0309 L / 22.4 L/mol = 1.38 X 10^-3 mol H2

1.38 X 10^-3 mol X 2.01 g/mol = 2.76 X 10^-3 grams

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