Final answer:
To prepare 150 cm³ of a 0.02 mol/dm³ NaOH solution, 0.12 g of NaOH is needed. The calculation involves converting volume to dm³, then using the molarity and the molar mass of NaOH to find the mass.
Step-by-step explanation:
To calculate the mass of NaOH needed to prepare a 0.02 mol/dm³ solution with a volume of 150 cm³, you need to use the formula:
mass (g) = molarity (mol/dm³) × volume (dm³) × molar mass of NaOH (g/mol)
First, convert the volume from cm³ to dm³ by dividing by 1000:
150 cm³ ÷ 1000 = 0.150 dm³
The molar mass of NaOH is approximately 40 g/mol.
Now, calculate the mass:
mass = 0.02 mol/dm³ × 0.150 dm³ × 40 g/mol = 0.12 g
Therefore, 0.12 g of NaOH is needed to prepare 150 cm³ of a 0.02 mol/dm³ NaOH solution.