A household cleaning agent contains a weak base of general formula NaX - HSC - SSCE Chemistry - Question 23 - 2001 - Paper 1

To find the molar mass of the base NaX, we first need to determine the amount of substance neutralized by hydrochloric acid. Using the titration data:

1. Calculate the number of moles of HCl used in the titration:

   $n = C \times V$

   where:

   • $C$ = concentration of HCl = 0.1000 mol L⁻¹

   • $V$ = volume of HCl used = 24.4 mL = 0.0244 L

   $n = 0.1000 \times 0.0244 = 0.00244 ext{ moles}$

2. Since NaX reacts with HCl in a 1:1 ratio, the number of moles of NaX in the 20.0 mL sample is also 0.00244 moles.

3. Given that 1.00 g of NaX was dissolved in 100.0 mL, the number of moles in the entire solution is:

   $\text{Total moles} = \frac{1.00 ext{ g}}{molar ext{ mass}}$

4. The molar mass can be calculated by equating and rearranging the equations:

   \text{Total moles} = 0.00244 rac{moles}{20 ext{ mL}} \cdot 1000 = 0.122 moles

   Solving for molar mass:

   $molar ext{ mass} = \frac{1.00 ext{ g}}{0.122 ext{ moles}} \approx 8.20 ext{ g/mol}$

Thus, the molar mass of the base NaX is approximately 8.20 g/mol.