Question

Suppose of zinc chloride is dissolved in of a aqueous solution of ammonium sulfate. Calculate the final molarity of zinc cation in the solution. You can assume the volume of the solution doesn't change when the zinc chloride is dissolved in it. Round your answer to significant digits.

Answer 1

The question is incomplete, here is the complete question:

Suppose 0.829 g of zinc chloride is dissolved in 100. mL of a 0.60 M aqueous solution of potassium carbonate. Calculate the final molarity of chloride anion in the solution. You can assume the volume of the solution doesn't change when the zinc chloride is dissolved in it. Round your answer to 2 significant digits.

Answer: The final molarity of chloride ion in the solution is 0.12 M

Explanation:

To calculate the number of moles for given molarity, we use the equation:

$\text{Molarity of the solution}=\frac{\text{Moles of solute}\times 1000}{\text{Volume of solution (in mL)}}$     .....(1)

• For potassium carbonate:

Molarity of potassium carbonate solution = 0.60 M

Volume of solution = 100. mL

Putting values in equation 1, we get:

$0.60M=\frac{\text{Moles of potassium carbonate}\times 1000}{100}\\\\\text{Moles of potassium carbonate}=\frac{(0.60\times 100)}{1000}=0.06mol$

• For zinc chloride:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Given mass of zinc chloride = 0.829 g

Molar mass of zinc chloride = 136.3 g/mol

Putting values in above equation, we get:

$\text{Moles of zinc chloride}=\frac{0.829g}{136.3g/mol}=0.0061mol$

The chemical equation for the reaction of potassium carbonate and zinc chloride follows:

$ZnCl_2+K_2CO_3\rightarrow ZnCO_3+2K^+(aq.)+2Cl^-(aq.)$

By stoichiometry of the reaction:

1 mole of zinc chloride reacts with 1 mole of potassium carbonate

So, 0.0061 moles of zinc chloride will react with = $\frac{1}{1}\times 0.0061=0.0061mol$ of potassium carbonate

As, given amount of potassium carbonate is more than the required amount. So, it is considered as an excess reagent.

Thus, zinc chloride is considered as a limiting reagent because it limits the formation of product.

By Stoichiometry of the reaction:

1 mole of zinc chloride produces 2 moles of chloride ion

So, 0.0061 moles of zinc chloride will produce = $\frac{2}{1}\times 0.0061=0.0122mol$ of acetate ion

Now, calculating the molarity of chloride ions in the solution by using equation 1:

Moles of chloride ion = 0.0122 moles

Volume of solution = 100. mL

Putting values in equation 1, we get:

$\text{Molarity of chloride ions}=\frac{0.0122\times 1000}{100}\\\\\text{Molarity of chloride ions}=0.12M$

Hence, the final molarity of chloride ion in the solution is 0.12 M