Question

A solution contains 5.3g of X₂CO₃ in 500 cm³ of solution. 25.0 cm³ of this solution required 20.0 cm³ of 0.25M hydrochloric acid for complete neutralization.
The equation for the reaction is;
X₂CO_3 (aq) + 2HCl _(aq)  →2XCl _(aq) + H₂O _(l) + CO_2 (g)

1. Calculate the concentration of X₂CO₃ solution in grams/dm^3.
2. Find the molarity of X₂CO₃ solution.
3. Find the relative formula mass of X₂CO₃ hence calculate the relative atomic mass of X.(C = 12, O = 16) 

Answer 1

1.   5.3 g →500 cm³
   ?       →1000 cm³
   ? = ^{(5.3 x1000)}/ ₅₀₀ =  10.6g/dm³ 
             
    
2.    Moles of HCl = ^{(20 x 0.25)}/₁₀₀₀ =0.005 
                              
   Moles of X₂CO₃ = ^0.05/₂ =0.0025 
                                    
   Molarity of X₂CO₃= ^{(0.0025 x 1000)}/₂₅ = 0.1 M
                                          
3.  Formula mass = ^10.6/_0.1 = 106 
                               
   2X +12+48 =106 
   X=23