Question

A chemist makes 0.800 L of zinc oxalate (ZnC2O4) working solution by adding distilled water to 0.100 L of a 0.000157 M stock solution of zinc oxalate in water
Calculate the concentration of the chemist's working solution. Round your answer to 3 significant digits.

Answer 1

To calculate the concentration of the chemist's working solution, we can use the dilution formula:

\[
C_1V_1 = C_2V_2
\]

where:
- \(C_1\) is the concentration of the stock solution,
- \(V_1\) is the volume of the stock solution,
- \(C_2\) is the concentration of the diluted solution (working solution),
- \(V_2\) is the volume of the diluted solution.

Given:
- \(C_1 = 0.000157 \, \text{M}\)
- \(V_1 = 0.100 \, \text{L}\)
- \(V_2 = 0.800 \, \text{L}\)

Now we can rearrange the formula to find \(C_2\):

\[
C_2 = \frac{C_1V_1}{V_2}
\]

Substituting in the values:

\[
C_2 = \frac{(0.000157 \, \text{M}) \times (0.100 \, \text{L})}{0.800 \, \text{L}}
\]

Calculating \(C_2\):

\[
C_2 = \frac{0.0000157 \, \text{mol}}{0.800 \, \text{L}}
\]

\[
C_2 = 0.000019625 \, \text{M}
\]

Now rounding to three significant digits:

\[
C_2 \approx 0.0000196 \, \text{M}
\]

So, the concentration of the chemist's working solution is:

\[
\boxed{0.0000196 \, \text{M}}
\]