In order to find out the acid concentration you need to know how many moles are in a measured volume
your units of g/dm3 are correct for gram concentration
I cant see how you arrived at the calcium hydroxide concentration of 3.92.
Your calculation of the hydrochloric acid concentration is fine.
Remember that at the titration end point the number of moles of acid and alkali are equal ifthe stoichiometry of the neutralisation reaction is 1:1
Calcium is in group 2 so the equation for the neutralisation is………….
HINT: the values given for the mass of calcium hydroxide used to make up the solution are not correct because the "solution" was filtered i.e. some of the calcium hydroxide which was weighed out did not dissolve!
Hope this helps and thanks for your contribution to the site Dr Bowker
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