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QuestionChemistry

Calculate the mass of KHC^8H^4O^4 ​(molar mass = 204.23 g/mol) that reacts with 15 mL of 0.15 M NaOH. Express this mass of KHC^8H^4O^4​ to the correct number of significant figures.
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Answer

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Step 1:
: Write the balanced chemical equation for the reaction between KHC^8H^4O^4 and NaOH.

The balanced chemical equation is: \boxed{ \begin{aligned} \text{KHC}_8\text{H}_4\text{O}_4 + \text{NaOH} \rightarrow \text{KNaC}_8\text{H}_4\text{O}_4 + \text{H}_2\text{O} \end{aligned} }

Step 2:
: Calculate the number of moles of NaOH present in the solution.

Use the formula for molarity (M = n/V) to find the number of moles (n). Rearrange the formula to solve for n: \boxed{ \begin{aligned} n = \text{Molarity} \times \text{Volume (in liters)} \end{aligned} } Calculate the number of moles: \boxed{ \begin{aligned} n_{\text{NaOH}} &= 0.15 \text{ M} \times 0.015 \text{ L} \ &= 0.00225 \text{ mol} \end{aligned} }

Step 3:
: Determine the number of moles of KHC^8H^4O^4 that reacts with 0.00225 mol NaOH.

Since both reactants are in a 1:1 mole ratio, 0.00225 mol of KHC^8H^4O^4 reacts completely with 0.00225 mol of NaOH.

Step 4:
: Calculate the mass of KHC^8H^4O^4 that reacts with 0.00225 mol NaOH.

Use the molar mass of KHC^8H^4O^4 (204.23 g/mol) to convert moles to grams: \boxed{ \begin{aligned} m_{\text{KHC^8H^4O^4}} &= n_{\text{KHC^8H^4O^4}} \times \text{Molar mass} \ &= 0.00225 \text{ mol} \times 204.23 \text{ g/mol} \ &= 0.462 \text{ g (rounded to three significant figures)} \end{aligned} }

Final Answer

The mass of KHC^8H^4O^4 that reacts with 15 mL of 0.15 M NaOH is 0.462 g.