Can we also use mass instead of molar mass when finding for percentage purity .!!!

No, you cannot directly use mass instead of molar mass when finding percentage purity. Here's why:

Percentage purity is defined as the ratio of the mass of the pure substance to the total mass of the sample, multiplied by 100.

Percentage Purity = (Mass of Pure Substance / Total Mass of Sample) × 100%

Molar mass is crucial because it relates the mass of a substance to the number of moles. When you perform a reaction (like titration) to determine the amount of pure substance, you are typically measuring the moles of reactant or product. You then use the molar mass to convert these moles back into a mass of the pure substance.

If you used the total mass of the sample directly in a calculation that requires moles (e.g., stoichiometry in a titration), your results would be incorrect because different substances have different masses per mole.