Question

DETERMINATION OF A CHEMICAL FORMUL 4. If some of the calcium metal remains unreacted when you start the titration, the calcium will react with hydrochloric acid to produce hydrogen gas. CaloH)₂ + 2HCl cacla & H2O Ca (s) + 2 HCl(aq) +CaCl2 (aq) + H2 (8) Would this cause error in the titration? If so, would more or less HCl be required? How would this affect the molecular formula for calcium hydroxide?

Answer 1

Q4:

Yes, there will be error in titration . The volume of HCl required would be more .

The molecular formula of calcium hydroxide would not be affected because Calcium and Ca(OH)₂ both reacts with HCl in same stoichiometric amount .

Q6

(a) OH^-(aq) + H⁺(aq) $\rightarrow$ H₂O(l)

(b)

Number of moles of Ca = 0.55g/40g/mol = 0.01375mol = moles of Ca(OH)₂

Number of moles of HCl = 2 × number of Moles of Ca = 2× 0.01375mol = 0.0275mol

The volume of HCl used = 0.0275mol/0.30mol/L = 0.091666L

= 91.67ml. (Answer)

(c) final burette reading = 25.60ml + 91.6667ml = 117.2666ml

= 117.27ml. (Answer)