Final answer:
Using the principle of conservation of mass, we find that 15 grams of sodium chloride are produced when 40 grams of sodium sulfate reacts with 35 grams of calcium chloride, yielding 20 grams of calcium sulfate.
Step-by-step explanation:
To solve the problem given, we need to apply the principle of conservation of mass, which states that matter is neither created nor destroyed in a chemical reaction. The total mass of reactants will equal the total mass of products. We start with 40 grams of sodium sulfate and 35 grams of calcium chloride.
The reaction produces 20 grams of calcium sulfate; therefore, to find the mass of sodium chloride produced, we use the following calculation:
Total mass of reactants = Total mass of products
40 g (sodium sulfate) + 35 g (calcium chloride) = 20 g (calcium sulfate) + x g (sodium chloride)
75 g (total reactants) = 20 g (calcium sulfate) + x g (sodium chloride)
Thus, x = 75 g - 20 g = 55 g
However, we have more reactants (75 g) than products (20 g), which means that the sodium chloride must account for the remaining mass:
x = 55 g - 40 g (initial sodium sulfate) = 15 g
Therefore, 15 grams of sodium chloride are produced.
The correct answer to the student's question is:
(c) 15 grams