For the reaction C + 2H2 → CH4, how many grams of hydrogen are required to produce 19.9 moles of methane, CH4 ?

Question

For the reaction C + 2H₂ → CH₄, how many grams of hydrogen are required to produce 19.9 moles of methane, CH₄ ?

Round your answer to the nearest tenth. If you answer is a whole number like 4, report the answer as 4.0

Use the following molar masses. If you do not use these masses, the computer will mark your answer incorrect.:

Element	Molar Mass
Hydrogen	1
Carbon	12

Answer 1

Use the following relationships:

19.9 mol CH4 = ? mol H2 (value given, value desired)

2.02 g H2 = 1 mol H2 (molar mass)

1 mol CH4 = 2 mol H2 (from the coefficients)

Convert from moles CH4 to moles H₂ via coefficients:

19.9 moles CH4 = ? mol H₂

1 mol CH4 = 2 mol H2

^19.9/₁ mol CH4 = ^x/₂ mol H₂

Now, x=mol of H₂

Convert mol H₂ to grams H₂ using molar mass

x=mol H2

1 mol H2 = 2.02 g H2

y = ? grams H2

x = whatever # you got before

y = the # you're solving for, and the final answer

grams / mol = grams / mol

2.02 / 1 = y / x

y = (2.02/1)x = grams of H₂

Answer 2

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