High School

What is the percent by mass of chlorine (Cl) in sodium chloride?

1) 35.5
2) 60.7
3) 0.606

Answer :

Final answer:

The percent composition of chlorine in sodium chloride is approximately 75.76% 35Cl and 24.24% 37Cl.

Explanation:

The percent by mass of chlorine (Cl) in sodium chloride (NaCl) can be calculated using the information about the isotopes of chlorine. Naturally occurring chlorine consists of two isotopes: 35Cl with an atomic mass of 34.96885 amu and abundance of 75.77%, and 37Cl with an atomic mass of 36.96590 amu and abundance of 24.23%. To find the percent composition of Cl in NaCl, we need to calculate the average mass of chlorine using these isotopes.

We can set up two equations:

Let x be the fraction of 35Cl (or percent abundance) and (1 - x) be the fraction of 37Cl. From these two equations, we can find that x = 0.7576, which means that (1 - x) = 0.2424. Therefore, chlorine consists of approximately 75.76% 35Cl and approximately 24.24% 37Cl in sodium chloride.