Question

what is the concentration of a solution formed by diluting 27.0 ml of a 4.5 m sucrose solution to 395. ml? be sure your answer has the correct number of significant figures.

Explanation:

Step1: State dilution formula

$C_1V_1 = C_2V_2$
where $C_1=4.5\ \text{M}$, $V_1=27.0\ \text{mL}$, $V_2=395\ \text{mL}$, $C_2$ = final concentration

Step2: Rearrange for $C_2$

$C_2 = \frac{C_1V_1}{V_2}$

Step3: Substitute values

$C_2 = \frac{4.5\ \text{M} \times 27.0\ \text{mL}}{395\ \text{mL}}$

Step4: Calculate and round sig figs

$C_2 = \frac{121.5}{395}\ \text{M} \approx 0.30759\ \text{M} \approx 0.31\ \text{M}$
(2 significant figures, from $C_1=4.5\ \text{M}$ which has the least)

Answer:

0.31 M