Question

What is the equivalent weight of arsenic in arsenous chloride?
A) 74.94
B) 24.98
C) 14.49
D) 49.96

Answer 1

Hint: The answer for this question includes the calculation of equivalent weight based on the definition of it which gives the formula as $Eq.Wt.=\dfrac{Mol.Wt.}{Change in O.N.permole}$

Complete step by step solution:
In the lower classes, we have studied the calculation of normality, molarity, molality, molecular weight, equivalent weight and various other physical quantities.
Let us now refresh the fact about what is equivalent weight and its calculation.
- Equivalent weight is the mass of a given substance which combines with or displaces a fixed quantity of other substances.
- Equivalent weight is also defined as the mass of one equivalent.
- Therefore equivalent weight in a molecule can be calculated as the ratio of atomic weight (in case of single atom) or formula weight (for compounds) to that of the change in the oxidation number per mole of the substance.
- Now, the above question is based on the arsenous chloride which is also called as arsenic trichloride that has the formula$AsC{{l}_{3}}$. It is also known by the name butter arsenic.
- Arsenous chloride is an inorganic compound which is poisonous oil and is colourless compound and when passed through any impure samples, it turns yellow.
Let us calculate the equivalent weight of arsenic in $AsC{{l}_{3}}$
Arsenic in its compound form has ‘+3’ oxidation state and atomic weight of As in $AsC{{l}_{3}}$=74.92 g/mol
Thus equivalent weight of arsenic =$\dfrac{74.92}{3}$ = 24.98.

Therefore, the correct answer is option B)

Note: Equivalent weight when measured in grams is also known as gram equivalent weight and can be defined in terms of mass of H atom as 1.008g of displacement or combination of H atoms and do not mark wrong answers.