Question

1-A reaction from lab should theoretically produce 95.08 grams of product. If the percent yield of this reaction is 56.65, how many grams did the reaction produce?

59.58

1.68

0.01

53.86

0.6

2-In lab, you observed and classified multiple reactions. You mix a clear blue solution and a clear yellow solution and observe the results to determine if a chemical reaction took place. Which of the following is NOT an indication that a chemical reaction took place?

The resulting solution appeared clear green.

The resulting solution violently bubbled.

The resulting mixture became neutral (underwent a pH change).

An orange precipitate was formed.

The resulting solution dropped in temperature.

Answer 1

1. Theoretically produced 95.08 grams of product.

Percent yield= 56.65%

Actual produced= 56.65% * 95.08 g

=> 53.86 grams

2. We mix a clear blue and a clear yellow solution.

Solution appearing clear green: colour change can be due to a chemical change.

Resulting solution violently bubbled: Violent bubbling is an indicator of rapid chemical reaction.

Resulting mixture becoming neutral: This does not indicate chemical reaction. Because pH can change by simple ionisation of the two solutions without interacting chemically with each other.

Orange precipitate: precipitate formation is an indicator of chemical reaction.

Resulting solution dropped in temperature: Negligible temperature change can result from mixing effect of solutions. But any significant change has to be due to chemical change.

Hence, resulting mixture becoming neutral is not indication that chemical reaction took place.