Question

Calculate the mass of sodium hydroxide needed to prepare 1000 cm³ of approximately 0.1 mol dm⁻³ aqueous solution.

a. 0.40 g
b. 1.00 g
c. 4.00 g
d. 10.00 g

Answer 1

To prepare 1000 cm³ of 0.1 mol dm⁻³ NaOH solution, 4.00 g of NaOH are required, which is calculated by multiplying the number of moles needed (0.1 mol) by the molar mass of NaOH (40.0 g/mol).

Step-by-step explanation:

To calculate the mass of sodium hydroxide (NaOH) needed to prepare 1000 cm³ of a 0.1 mol dm⁻³ solution, we need to follow these steps:

1. Understand that 1000 cm³ is equivalent to 1 dm³, which is the same as 1 L.
2. Calculate the number of moles of NaOH needed using the concentration and volume.
   0.1 mol dm⁻³ × 1 dm³ = 0.1 mol of NaOH.
3. Calculate the mass of NaOH using its molar mass.
   0.1 mol × 40.0 g/mol = 4.00 g of NaOH.

Therefore, the mass of sodium hydroxide needed is 4.00 g.