Question

6.5 grams of zinc reacted with hydrochloric acid. Calculate how many grams of hydrogen were released. a) 0.1 g. b) 0.2 g. c) 1.0 g. d) 2.0 g.

Answer 1

0.2 grams

Explanations

The balanced reaction between zinc and hydrochloric acid is given as:

`Zn+2HCl\rightarrow ZnCl_2+H_2`

Given the following parameters

Mass of Zinc = 6.5grams

Determine the mole of Zinc

Mole of Zn = mass/molar mass

Mole of Zn = 6.5/65.38

Mole of Zn = 0.0994moles

According to stoichiometry, 1 mole of Zinc produced 1 mole of hydrogen gas, hence the mole of hydrogen gas required will be 0.0994moles

Determine the mass of hydrogen gas produced

`\begin{gathered} Mass\text{ of H}_2=mole* molar\text{ mass} \\ Mass\text{ of H}_2=0.0944moles*2.016 \\ Mass\text{ of H}_2=0.19g\approx0.2grams \end{gathered}`

Hence the mass of hydrogen that were released is 0.2 grams