Question

In a laboratory experiment, a $15.0‐\mathrm{mL}$sample of $\mathrm{KCl}$the solution is poured into an evaporating dish a mass of $24.10\mathrm{g}$. The combined mass of the evaporating dish and $\mathrm{KCl}$solution is $41.50\mathrm{g}$. After heating, the evaporating dish and dry $\mathrm{KCl}$have a combined mass of $28.28\mathrm{g}.(9.4)$

a. What is the mass percent localid="1653296764554" $\left(\mathrm{m}/\mathrm{m}\right)$of the $\mathrm{KCl}$solution?

b. What is the molarity $\left(\mathrm{M}\right)$of the $\mathrm{KCl}$solution?

c. If water is added to $10.0\mathrm{mL}$of the initial $\mathrm{KCl}$solution to give a final volume of $60.0\mathrm{mL}$, what is the molarity of the diluted $\mathrm{KCl}$solution?

Short answer

a. The mass percent $(\mathrm{m}/\mathrm{m})$of the $\mathrm{KCl}$solution is $24\%$.

b. The molarity $\left(\mathrm{M}\right)$of $\mathrm{KCl}$the solution is $1.61\mathrm{M}$.

c. the molarity of the diluted $60.0\mathrm{mL}$solution is $0.27\mathrm{M}$.

Step-by-step solution

Part (a) Step 1: Given Information

Amount of KCL = $15ml$

Mass of evaporating dish = $24.10g$

Combined mass = $41.50g$and after heating the mass = $28.28g$

Finding the mass percent of the KCL solution

Part (a) Step 2: Explanation

Now,

Calculating the mass percent,

$\left(\mathrm{m}/\mathrm{m}\right)=\frac{28.28\mathrm{g}-24.10\mathrm{g}}{41.50\mathrm{g}-24.10\mathrm{g}}=0.24$

the mass percent is$0.24\%$.

Part (b) Step 1: Given Information

Amount of KCL =$15ml$

Mass of evaporating dish =$24.10g$

Combined mass =$41.50g$ and after heating the mass =$28.28g$

finding the molarity $\left(\mathrm{M}\right)$of the $\mathrm{KCl}$solution.

Part (b) Step 2: Explanation

Here,

Calculating the molarity,

$\mathrm{c}=\frac{24.10\mathrm{g}}{15\mathrm{mL}}=1.61\mathrm{M}$

the molarity is$1.61\mathrm{M}$.

Part (c) Step 1: Given Information

Amount of KCL =$15ml$

Mass of evaporating dish =$24.10g$

Combined mass = $41.50g$and after heating the mass =$28.28g$

finding the molarity of the diluted $60.0\mathrm{mL}$solution.

Part (c) Step 2: Explanation

Now,

Calculating the molarity of the diluted $60.0\mathrm{mL}$,

${\mathrm{c}}_2=\frac{{\mathrm{c}}_1\times {\mathrm{V}}_1}{{\mathrm{V}}_2}=\frac{1.61\mathrm{M}\times 10\mathrm{mL}}{60\mathrm{mL}}=0.27\mathrm{M}$