Physical Chemistry - Stoichiometry Question

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Question : An organic compound X contains by mass, 63.2% carbon,
8.7% hydrogen, and 28.1% oxygen. On treatment with sodium
hydrogencarbonate solution, it liberates carbon dioxide. It also
undergoes an addition reaction with bromine in a 1:1 molar ratio
whereby 1.50 g of the compound reacts with 2.11 g of bromine.

 (i) Calculate the empirical formula of X. 

(ii) Calculate the relative molecular mass of X. 

(iii) Determine the molecular formula of X. 

Answer : Molecular formula of X is C6H10O2

Bonus question : 25.0 cm3 of a solution containing sodium hydroxide and sodium carbonate required
21.05 cm
3 of 1 mol dm-3 HCl with phenolphthalein as indicator and a further 6.80 cm3of the same acid with methyl orange as indicator. Calculate the molar concentration of
each compound in the solution.

conc of sodium carbonate = 0.272 mol dm-3

conc of sodium hydroxide = 0.570 moldm-3