Question

What is the concentration of a solution of a 40.0 g of NaOH in 2.5 L of solution?

Answer 1

Answer: 0.4M

Explanation:

Given that,

Amount of moles of NaOH (n) = ?

Mass of NaOH in grams = 40.0g

For molar mass of NaOH, use the atomic masses: Na = 23g; O = 16g; H = 1g

NaOH = (23g + 16g + 1g)

= 40g/mol

Since, n = mass in grams / molar mass

n = 40.0g / 40.0g/mol

n = 1 mole

Volume of NaOH solution (v) = 2.5 L

Concentration of NaOH solution (c) = ?

Since concentration (c) is obtained by dividing the amount of solute dissolved by the volume of solvent, hence

c = n / v

c = 1 mole / 2.5 L

c = 0.4 mol/L (Concentration in mol/L is the same as Molarity, M)

Thus, the concentration of a solution of a 40.0 g of NaOH in 2.5 L of solution is 0.4 mol/L or 0.4M