Question

How many grams of solute are needed to make 250 mL of a 2.055 M NaCl solution?

Answer 1

Answer:

30grams

Explanation:

To calculate the mass (number of grams of the solute) in the solution, we need to calculate the number of moles it contains first. We use the formula;

M = n÷ V

Where; M= Molarity or Molar concentration = 2.055M

n= number of moles= ?

V= Volume = 250mL

Volume in L is 250/1000 = 0.250L

n= M × V

n= 2.055 × 0.250

n= 0.51375moles

The mass is calculated using :

Mole (n) = mass (m) / molar mass (MM)

Molar mass of NaCl = 23 + 35.5

= 58.5g/mol

Mass = molar mass × mole

Mass = 58.5 × 0.51375

Mass = 30.0543

Therefore, the mass is 30grams