High School

The chloride of a metal contains 71% chlorine by weight, and the vapor density is 50. What is the atomic weight of the metal?

A. 29
B. 58
C. 35.5
D. 71

Answer :

The atomic weight of the metal in the given compound with 71% chlorine by weight and a vapor density of it is 50. The atomic weight of the metal will be: 50, hence none of the option is correct.

Mass Percentage of Chlorine: The problem states that the chloride contains 71% chlorine by weight. This means for every 100 grams of the chloride, 71 grams are chlorine and the remaining 29 grams are the metal.

Let x be the Atomic Weight of the Metal:

We don't know the metal's atomic weight yet, so we'll represent it as 'x'.

Molar Ratio in the Chloride: In the chloride compound, one atom of the metal (M) combines with one atom of chlorine (Cl). Therefore, the ratio of their masses in the compound reflects the ratio of their atomic weights.

Setting up a Proportion: We can set up a proportion to relate the mass of chlorine (71 grams) to the total mass of the chloride (100 grams) and the ratio of their atomic weights:

(Mass of Cl) / (Total Mass) = (Atomic weight of Cl) / (Atomic weight of Metal)

71 grams / 100 grams = 35.5 grams/mol (atomic weight of Cl) / x grams/mol

Solving for x (Atomic Weight of Metal):

Cross-multiplying and solving for x:

x * (71 grams) = 100 grams * (35.5 grams/mol)

x ≈ 50 grams/mol (rounded to one decimal place)

Therefore, the atomic weight of the metal is approximately 50.