Question

A solid sample (Sample 1) is analyzed and found to contain 1.47 g carbon and 0.123 g hydrogen. A second sample (Sample 2) is expected to be composed of the same pure compound. If Sample 2 is found to contain 2.17 g hydrogen, how much carbon is expected in the sample ?

Answer 1

Carbon is sample 2 = 25.9 g

Explanation

For sample 1,

mass carbon = 1.47 g

moles carbon = (mass carbon) / (molar mass carbon)

moles carbon = (1.47 g) / (12.01 g/mol)

moles carbon = 0.1224 mol

mass hydrogen = 0.123 g

moles hydrogen = (mass hydrogen) / (molar mass hydrogen)

moles hydrogen = (0.123 g) / (1.008 g/mol)

moles hydrogen = 0.122 mol

moles carbon / moles hydrogen = (0.1224 mol) / (0.122 mol)

moles carbon / moles hydrogen = 1.003

For sample 2,

mass hydrogen = 2.17 g

moles hydrogen = (mass hydrogen) / (molar mass hydrogen)

moles hydrogen = (2.17 g) / (1.008 g/mol)

moles hydrogen = 2.1528 mol

moles carbon = (moles hydrogen) * (moles carbon / moles hydrogen)

moles carbon = (2.1528 mol) * (1.003)

moles carbon = 2.16 mol

mass carbon = (moles carbon) * (molar mass carbon)

mass carbon = (2.16 mol) * (12.01 g/mol)

mass carbon = 25.9 g