Question

a student is given two 10g samples, each a mixture of only nacl(s) and kcl(s) but in different proportions. which of the following pieces of information could be used to determine which mixture has the higher proportion of kcl(s) ? a the volume of each mixture b the mass of cl in each mixture c the number of isotopes of na and k d the reaction of each mixture with water

Explanation:

• Option A: Volume of the mixture doesn't directly relate to the proportion of KCl since we don't know the density relationship specific to KCl and NaCl proportions here.
• Option B: KCl has a lower mass percentage of Cl compared to NaCl (KCl: $\frac{35.45}{74.55}\approx0.475$, NaCl: $\frac{35.45}{58.44}\approx0.607$). So a lower mass of Cl in the 10g mixture would mean a higher proportion of KCl (since KCl contributes less Cl per gram). This can be used to compare proportions.
• Option C: Number of isotopes of Na and K is irrelevant to the proportion of KCl in the mixture.
• Option D: Both NaCl and KCl are soluble in water, and their reaction with water doesn't differ in a way that would indicate KCl proportion.

Answer:

B. The mass of Cl in each mixture