Question

f 27.0 mL of Ca(OH)2 with an unknown concentration is neutralized by 32.40 mL of 0.185 M HCl, what is the concentration of the Ca(OH)2 solution? Show all of the work needed to solve this problem.

Ca(OH)2 + 2 HCl 2 H2 O + CaCl2

Answer 1

Please post chemistry questions in the chemistry forum, and so on, next time onwards.

\[\large Ca(OH)_2 + 2HCl --->CaCl_2 + 2H_2O \]
So you see,
You require 2 moles of HCl per mole of calcium hydroxide in the reaction.

0.185M HCl means 0.185 moles of HCl in every litre of it.
So, 32.40 ml, that is 0.0324 moles of the solution will contain = 0.0324 * 0.185 moles.

Now this HCL requires half it's own no. of moles of calcium chloride to neutralise.

so, find out the no. of moles of CaCl2 reqd, which is also the no. of moles present in its solution.


Now, you will have the volume of of CaCl2 solution taken, total no. of moles that were present in it - find out its molarity.