Chapter 2 - Atoms and the Atomic Theory - Exercises - Law of Conservation of Mass - Page 60: 4

$m_{KCl}$ = 2.757 g

The mass of the products and the mass of the reactants are equal. This is stated in the Law of Conservation of Mass. So $m_{reactants} = m_{products}$ $m_{K} + m_{Cl_{2}} = m_{KCl}$ $ m_{K}$ = 1.446 g $m_{Cl_{2}}$ = 8.178 - 6.867 = 1.311 g 1.446 + 1.311 = $m_{KCl}$ $m_{KCl}$ = 2.757 g Rounding to four significant figures gives $m_{KCl}$ = 2.757 g