Question

Find moles of 3.5 mg of hydrogen gas

Answer 1

Number of moles can be calculated using the following equation:

n = m / Mr

where n - number of moles, m - mass, Mr - molecular weight

As Mr(H₂) = 2, the number of moles of hydrogen gas equals:

n = 3.5 mg / 2 g/mol = 0.0035 g / 2g/mol = 0.00175 mol

Answer: 0.00175 mol