Use the atomic masses of the elements to determine the percent composition by mass of sodium and chlorine in sodium chloride.

Explanation:

Percent composition of sodium chloride .

NaCl

Mol weight = 23 + 35.5 = 58.5 g

58.5 g of NaCl contains 23 g of Na

100 g of NaCl contains 23 x 100 / 58.5 g of Na

= 39.3 %

Na = 39.3 %

58.5 g of NaCl contains 35.5  g of Cl

100 g of NaCl contains 35.5 x 100 / 58.5 g of Na

= 60.7 %

Cl = 60.7 % .

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