Question

Thirty grams of potassium chloride crystals are added to 400 mL of water. What is the molarity of this potassium chloride solution?
A.
1.0 M
B.
13.3 M
C.
0.186 M
D.
0.075 M

Answer 1

Answer:

Molarity of potassium chloride is:

A. 1.0 M

Explanation:

Molarity is used to express the concentration of the solution.It is defined as the moles of solutes per liter volume of solution.It is denoted by M.

$molarity(M)=\frac{moles\ of\ solute}{volume\ of\ solution(ml)}\times 1000$

$M=\frac{n}{V(ml)}\times 1000$

Here'n' is the number of moles. It can be calculated using formula:

$n=\frac{given\ mass(w)}{molar\ mass}$

given mass=30 gm

Molar mass of KCl = mass of K+mass of Cl

                               = 39.098+34.45

                               = 74.55 g

$n=\frac{30}{74.55}$

n = 0.402 moles

$M=\frac{n}{V(ml)}\times 1000$

$M=\frac{0.402}{400}\times 1000$

$M=\0.001\times 1000$

M=1.00 M

So molarity of potassium chloride is 1.00 M