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[angmor]

4.06g of impure magnesium oxide was completly dissolved in 100cm3 of HCL, of concentration 2M(in excess). the excess acid required 19.7 cm3 of sodium hydroxide (0.20 mol dm-3) for neutralisation.

1. write equations for the two neutralisation reactions
2. calculate the moles of hcl added to the magnesium oxide
3. calculate the moles of excess hcl titrated


thanks very much

 

[Riviet]

1. MgO + 2HCl -> MgCl₂ + H₂O

HCl + NaOH -> NaCl + H₂0

2. n_HCl=cv
=2x0.1
=0.2mol
.'. 0.2 moles of HCl added.

3. The number of moles of excess HCl refers to the number of moles of HCl in the second equation.
n_NaOH=cv
=0.2x19.7
=3.94
1 mole of HCl reacts with 1 mole of NaOH
.'. 3.94 moles of excess HCl are titrated.

Hope that helps.

 

[angmor]

tyvm ^^