Question

how many ml of formic acid would you add to water to make 755 ml of a 25.0% by volume formic acid solution?

Explanation:

Step1: Recall volume percent formula

The formula for volume percent (\(v/v\%\)) is \(v/v\%=\frac{\text{Volume of solute}}{\text{Volume of solution}}\times100\). We need to find the volume of formic acid (solute), let's call it \(V_{\text{solute}}\). The volume of the solution \(V_{\text{solution}} = 755\space mL\) and \(v/v\% = 25.0\%\).

Step2: Rearrange the formula to solve for \(V_{\text{solute}}\)

From \(v/v\%=\frac{V_{\text{solute}}}{V_{\text{solution}}}\times100\), we can rearrange it to \(V_{\text{solute}}=\frac{v/v\%\times V_{\text{solution}}}{100}\).

Step3: Substitute the values

Substitute \(v/v\% = 25.0\), \(V_{\text{solution}} = 755\space mL\) into the formula: \(V_{\text{solute}}=\frac{25.0\times755}{100}\).

Calculate \(25.0\times755 = 18875\), then divide by 100: \(\frac{18875}{100}=188.75\space mL\).

Answer:

\(189\space mL\) (or \(188.75\space mL\) depending on significant figures, here 25.0 has three, 755 has three, so the answer can be \(189\space mL\) or \(188.75\space mL\))