How much sodium hydroxide is required to make 250 cm³ of 0.1 molar solution? [Na=23; 0=16; H=1]

Explanation

To find the mass of sodium hydroxide (NaOH) needed, we first calculate its molar mass. NaOH = Na + O + H = 23 + 16 + 1 = 40 g/mol.

Next, we find the number of moles needed using the formula: moles = concentration × volume (in dm³). We must convert 250 cm³ to dm³: 250 cm³ = 250 / 1000 = 0.25 dm³.

So moles = 0.1 mol/dm³ × 0.25 dm³ = 0.025 mol.

Finally, we convert moles to mass using: mass = moles × molar mass = 0.025 × 40 = 1.0 g.

Therefore, 1.0 g of sodium hydroxide is needed to prepare 250 cm³ of a 0.1 molar solution.