## Chemistry and Chemical Reactivity (9th Edition)

a) $Mg(OH)_2+2\ HCl\rightarrow MgCl_2+2\ H_2O$ b) Number of moles of HCl: $29.52\ mL\times0.500\ M=14.76\ mmol$ Number of moles of $CaCO_3$: $550\ mg \div 100.09\ mg/mmol=5.50\ mmol$ From stoichiometry, the number of moles of the hydroxide: $(14.8-2/1\times5.50)\ mmol\times1/2=1.88\ mmol$ $1.88\ mmol\times58.32\ mg/mmol=110.\ mg$