Question

Use the problem below to answer the question: When a current is passed through a solution of salt water, sodium chloride decomposes according to the following reaction: NaCl + H2O → NaOH + Cl2 + H2 How many grams of chlorine gas, Cl2 are given off if 7.5 grams of sodium chloride, NaCl, are decomposed? Is this equation balanced?

Answer 1

Answer: 4.544 grams of chlorine gas is produced in the given reaction.

Explanation: Number of moles can be calculated by using the formula:

`Moles=\frac{\text{given mass}}{\text{Molar mass}}` ... (1)

Molar mass of NaCl = 58.5 g/mol

Given mass of NaCl = 7.5 grams

Moles of NaCl is calculated by:

`Moles=(7.5g)/(58.5g/mol)`

Moles of NaCl = 0.128 moles

The given equation is not balanced. For any further calculation, we first need to balance the equation.

The balanced chemical equation follows:

`2NaCl+2H_2O\rightarrow 2NaOH+Cl_2+H_2`

By Stoichiometry,

2 moles of NaCl produce 1 mole of chlorine gas

So, 0.128 moles of NaCl will produce =
`(1)/(2)* 0.128` = 0.064 moles of chlorine gas

Mass of Chlorine gas is calculated by using equation 1, we get

Molar mass of
`Cl_2` = 71 g/mol

Putting the values in above equation, we get

`0.064mol=\frac{\text{Given mass}}{71g/mol}`

Mass of
`Cl_2` produced = 4.544 grams