Question

0.161 l of a 0.189 m solution is left on a hotplate overnight and the following morning the solution is 1.51 m. what volume of solvent (in ml) has evaporated from the solution left on the hotplate overnight? please enter your answer using scientific notation and to three significant figures.

Explanation:

Step1: Calculate the initial amount of solute

Use the formula \(n = C\times V\), where \(C\) is concentration and \(V\) is volume.
\(n = 0.189\space M\times0.161\space L= 0.030429\space mol\)

Step2: Calculate the final volume of the solution

Since the amount of solute \(n\) remains the same (only solvent evaporates), use \(V=\frac{n}{C}\).
\(V=\frac{0.030429\space mol}{1.51\space M}=0.0201516556\space L\)

Step3: Calculate the volume of evaporated solvent

Initial volume \(V_{initial}=0.161\space L = 161\space mL\), final volume \(V_{final}=0.0201516556\space L = 20.1516556\space mL\)
\(V_{evaporated}=161\space mL - 20.1516556\space mL = 140.8483444\space mL\approx1.41\times 10^{2}\space mL\)

Answer:

\(1.41\times 10^{2}\space mL\)