If 2 grams of substance A react completely with 3 grams of substance B, what must be true about the products?



2 A plus 1 B yields 3 C plus 1 D

Answer options with 5 options
A.
1 gram of substance B is left over

B.
2 moles of substance A are used

C.
4 grams of products are produced

D.
4 moles of products are produced

E.
5 grams of products are produced

1 answer

To analyze the reaction given:

Reactants:

  • 2 grams of substance A
  • 3 grams of substance B

Reaction:

  • 2 A + 1 B → 3 C + 1 D

Products:

  • 3 moles of C
  • 1 mole of D

Now, let's evaluate the options one by one:

A. 1 gram of substance B is left over

  • This statement can't be true because it is mentioned that substance A reacts completely with substance B. Since 2 grams of A reacts with 3 grams of B, the reaction consumes all of both reactants.

B. 2 moles of substance A are used

  • The reaction indicates that 2 moles of substance A are required, but the statement doesn't provide enough context about the molar mass of item A to confirm. Without that information, this statement can't be concluded definitively.

C. 4 grams of products are produced

  • The total mass before the reaction is 2 grams (A) + 3 grams (B) = 5 grams. According to the law of conservation of mass, the total mass of the reactants will equal the total mass of the products. Therefore, 4 grams of products cannot be true, since that would not account for the total mass.

D. 4 moles of products are produced

  • The products consist of 3 moles of C and 1 mole of D, which totals 4 moles (3 + 1 = 4). This statement is true.

E. 5 grams of products are produced

  • Considering conservation of mass, since 2 grams of A and 3 grams of B react together, the total mass of products must also be 5 grams. This statement is also true.

Given these evaluations, the correct answers are:

D. 4 moles of products are produced and E. 5 grams of products are produced.