A student performs a titration to find the concentration of a calcium hydroxide solution, Ca(OH)2\text{Ca(OH)}_2Ca(OH)2, using a 0.100 mol/dm30.100\text{ mol/dm}^30.100 mol/dm3 solution of hydrochloric acid, HCl\text{HCl}HCl.
In each titration, the student transfers 25.0 cm325.0\text{ cm}^325.0 cm3 of the calcium hydroxide solution into a conical flask using a pipette.
The table shows the volume of acid added in four titration runs:
Titration run1234Volume of acid added (cm3)23.1022.4522.5522.50\begin{array}{|l|c|c|c|c|} \hline \text{Titration run} & 1 & 2 & 3 & 4 \\ \hline \text{Volume of acid added (cm}^3\text{)} & 23.10 & 22.45 & 22.55 & 22.50 \\ \hline \end{array}Titration runVolume of acid added (cm3)123.10222.45322.55422.50Concordant results are those within 0.20 cm30.20\text{ cm}^30.20 cm3 of each other. Identify the concordant results and use them to calculate the average (mean) volume of acid added.
The equation for the reaction is:
2HCl+Ca(OH)2→CaCl2+2H2O 2\text{HCl} + \text{Ca(OH)}_2 \rightarrow \text{CaCl}_2 + 2\text{H}_2\text{O} 2HCl+Ca(OH)2→CaCl2+2H2OCalculate the concentration, in mol/dm3\text{mol/dm}^3mol/dm3, of the calcium hydroxide solution.
