Chemical Solutions | MCQs

Explanation

To prepare 250 cm³ (or 250 mL) of a 1 M NaOH solution, you need 10 grams of NaOH.

This is because the molar mass of NaOH is 40 g/mol, and a 1 M solution contains 1 mole of solute per liter of solution.

Therefore, 250 mL (0.25 L) of a 1 M solution would require 0.25 moles of NaOH, which translates to 10 grams (0.25 moles * 40 g/mol). 

Explanation

To calculate formality, we need to know the number of moles of dichloromethanic acid and the volume of the solution in liters.

Number of moles = mass / molecular weight

= 6.447 g / 128.94 g/mol

≈ 0.05 mol

Formality = number of moles / volume (in liters)

= 0.05 mol / 0.5 L

= 0.1 F