Question

Two samples of sodium chloride were decomposed into their constituent elements. One sample produced 2.84 g of sodium and 4.37 g of chlorine. Which of the following could be the results of the decomposition of the other sample, being consistent with the law of constant composition (also called the law of definite proportions or law of definite composition)?

a) 4.17 g of sodium and 3.75 g of chlorine
b) 4.17 g of sodium and 6.42 g of chlorine
c) 4.17 g of sodium and 1.05 g of chlorine
d) 4.17 g of sodium and 12.1 g of chlorine

Answer 1

The correct answer is b) 4.17 g of sodium and 6.42 g of chlorine

Step-by-step explanation:

According to the law of definite proportions a chemical compound is composed always by the same elements in the same proportions by mass. In this case, the proportion of the elements by mass will be 4.37 g of chlorine (Cl) per 2.84 g of sodium (Na):

4.37 Cl/2.84 g Na= 1.54

We can calculate the proportions of the results in order to see which is the correct:

a) 3.75 g Cl/4.17 g Na = 0.899

b) 6.42 g Cl/4.17 g Na = 1.539 ⇒ ≅1.54

c) 1.05 g Cl/4.17 g Na = 3.971

d) 12.1 g Cl/4.17 g Na = 2.901

The option in which the proportion Cl/Na is equal to 1.54 is option b