Final answer:
To prepare a 0.1 molar dm⁻³ solution of sodium hydroxide, you would need approximately 4.0 g of sodium hydroxide.
Step-by-step explanation:
To calculate the mass of sodium hydroxide needed to prepare a 0.1 molar dm⁻³ solution, we first need to determine the number of moles of sodium hydroxide required.
Using the formula:
moles = molarity x volume (in dm³),
we can calculate the number of moles of sodium hydroxide:
moles = 0.1 mol/dm³ x 1 dm³ = 0.1 mol
Next, we need to determine the mass of sodium hydroxide required. The molar mass of sodium hydroxide (NaOH) is 40.0 g/mol. Therefore, the mass of sodium hydroxide needed is:
mass = moles x molar mass = 0.1 mol x 40.0 g/mol = 4.0 g