Question

The solubility of potassium chloride at ${20^ \circ }C$ is $34.7g$ in $100g$ of water. The density of the solution is $1.3gm{L^{ - 1}}$ . What is the w/V percentage of potassium chloride in the solution?
A. $25.76$
B. $32.98$
C. $33.49$
D. $22.56$

Answer 1

This is a quantitative question and therefore formulas would be used. According to the question and the values given, we will first find density and then we can find the weight by volume percentage.

Complete step by step answer:
This is a calculative question. The formula for density will be used to find the answer to this question. First, the formula of density is as given below
$d = \dfrac{m}{V}$
Substituting the values for the solution we get,
$d = \dfrac{{(34.7 + 100)}}{V}$
$1.3 = \dfrac{{34.7 + 100}}{V}$
$V = \dfrac{{134.7}}{{1.3}} = 103.61ml$
Now, for finding weight/Volume percentage of $KCl$ in $100ml$ of solution,
$103.61 \, ml$ of $KCl$ contains $34.7g$ of $KCl$
$100ml$ of $KCl$ contains,
$\dfrac{{34.7}}{{103.61}} \times 100 = 33.49\%$

**Therefore, the correct answer is option C.

Additional Information:**
We can know something about Potassium chloride. It is a metal salt composed of potassium and chlorine. It is odourless and has a white crystal appearance. It dissolves readily in water and its solutions have a salt-like taste. It could be obtained from ancient dried lake deposits. It is used as a fertilizer, in medicine, scientific applications and food processing. It is also found in many foods and is needed for several functions of your body and especially for the beating of your heart.

Note:
Calculating values can sometimes be difficult if we don’t take care of units. Taking care of units is important like $L$ and $ml$ or $ml$ and $g$ as given in the example.