A0.450 g sample of impure caco 3 ( s ) is dissolved in 50.0 ml of 0.150 m hcl ( aq ) . the equation for the reaction is caco 3 ( s ) + 2 hcl ( aq ) ⟶ cacl 2 ( aq ) + h 2 o ( l ) + co 2 ( g ) the excess hcl ( aq ) is titrated by 6.45 ml of 0.125 m naoh ( aq ) . calculate the mass percentage of caco 3 ( s ) in the sample.