Question

Determine the concentration of a solution made by dissolving 1.40grams NaCL in enough water to make 30.0mL of solution.

Answer 1

Answer: 0.8M

Explanation:

Given that,

Amount of moles of NaCl (n) = ?

Mass of NaCl in grams = 1.40 g

For molar mass of NaCl, use the molar masses:

Sodium, Na = 23g;

Chlorine, Cl = 35.5g

NaCl = (23g + 35.5g)

= 58.5g/mol

Since, amount of moles = mass in grams / molar mass

n = 1.40g / 58.5g/mol

n = 0.024 mole

Now, given that:

Amount of moles of NaCl (n) = 0.024

Volume of NaCl solution (v) = 30.0mL

[Convert 30.0mL to liters

If 1000 mL = 1L

30.0mL = 30.0/1000 = 0.03L]

Concentration of NaCl solution (c) = ?

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

c = n / v

c = 0.024 mole / 0.03 L

c = 0.8 M (0.8M means concentration is in moles per litres)

Thus, the concentration of the solution is 0.8M