To determine the mass of NaOH required to produce a given concentration of 0.2 mol/dm³ in a solution volume of 100.0 cm³, we can use the formula:
Mass (g) = Concentration (mol/dm³) × Volume (dm³) × Molar mass (g/mol)
The molar mass of NaOH (sodium hydroxide) is 40.0 g/mol.
Plugging in the values:
Mass (g) = 0.2 mol/dm³ × 0.100 dm³ × 40.0 g/mol
Mass (g) = 0.2 × 0.100 × 40.0
Mass (g) = 0.8 g
Therefore, 0.8 grams of NaOH would be needed to produce 100.0 cm³ of a 0.2 mol/dm³ solution.