Question

The molarity of a solution of 5.0 g of KCl in 100. mL of solution is ________. A) 0.038 M B) 0.067 M C) 0.67 M D) 0.13 M E) 1.3 M

Answer 1

`\huge{ \boxed{0.67 \: \text{M}}}`

Step-by-step explanation:

The molarity of the solution can be found by using the formula:

`c = (m)/(M * v)`

c is the concentration in M , mol/dm³ or mol/L

v is the volume in L or dm³

m is the mass in grams

M is the molar mass in g/mol

From the question;

mass = 5 g

Molar mass (M) of KCl = 39 + 36.5 = 75.5 g/mol

Since the volume is in mL it has to be converted to litres.

`1000ml = 1l \\ \therefore \: 100ml = (100ml)/(1000ml) * 1l \\ = 0.1l`

v = 0.1 L

`\therefore \: c = (5)/(75.5 * 0.1) \\ = 0.67 \:`

We have the final answer as;

0.67 M