Calculate the morality of each of the following solutions: a. 15.4 g KCl in 289.2 mL solution b. 14.4 g of CaCl2 in 0.614 L solution c. 28.0 mL of 3.00 M H2SO4 diluted to 0.250 L

The answer is:

a. 0.712 M

b. 0.210 M

c. 0.336 M

Molarity is a measure of the concentration of solute in a solution.

It can be expressed as moles of solute : volume of solution:

c = n : V

where:

c - concentration of solute,

n - moles of solute

V - volume of solution

n can be expressed as:

n = m : Mr

where:

n - moles of solute

m - mass of solute

Mr - relative molecular mass

a. We know volume:

V = 289.2 mL = 0.2892 L

We need n and c.

n = m : Mr

m = 15.4 g

Mr (KCl) = 74.55 g/mol

n = 15.4 g : 74.55 g/mol

n = 0.206 mol

Thus,

c = 0.206 mol : 0.2892 L

c = 0.712 mol/L = 0.712 M

b. We know volume:

V = 0.614 L

We need n and c.

n = m : Mr

m = 14.4 g

Mr (CaCl₂) = 110.98 g/mol

n = 14.4 g : 110.98 g/mol

n = 0.129 mol

Thus,

c = 0.129 mol : 0.614 L

c = 0.210 mol/L = 0.210 M

c. We can use formula:

m₁V₁ = m₂V₂

m₁ = 3 M

V₁ = 28 mL = 0.028 L

m₂ = ?

V₂ = 0.250 L

Thus:

3 M * 0.028 L = m₂ * 0.250 L

m₂ = 0.336 M