Astudent designs an experiment to test substances x, y, and z, to determine which one is a catalyst for the reaction: a + b ® c. only one of the unknown substances is a catalyst, and the others are nonreactive with a, b, or c. when 10 ml of a is added to 10 ml of b, the reaction takes twenty seconds. bubbles form when the product c is created. the student prepares three test tubes, each containing both reactants a and b. she adds unknowns x, y, and z to test tubes 1, 2, and 3, respectively. she then times the reaction in each test tube from the point when the unknown is added until bubbling stops. how can the student identify the catalyst? the test tube that stops bubbling first contains the catalyst. the test tube that produces the most bubbles contains the catalyst. the test tube that bubbles the longest contains the catalyst. the test tube that does not bubble contains the catalyst.

A.The test tube that stops bubbling first contains the catalyst.

Explanation:

We are given that a student design an experiment to test substances X,Y and Z.

We have to determine the catalyst.

The reaction is

A+B

When 10 mL of A is added to 10mL of B, the reaction takes 20 seconds.Bubbles formed when the product C is formed.The student prepare three test tubes, each containing both reactants A and B. She adds unknowns X,Y and Z to test tube 1,2 and 3 respectively.She then times the reaction in each test tube from the point when the unknown i added untill bubbling stops.

Catalyst: The catalyst does not change in the reaction . It increases the rate of reaction and lower the activation energy. When the catalyst combine with reactant it form intermediate complex then it directly gives the product and regenerate the catalyst.

The test tube that stops bubbling first contains the catalyst.Because the catalyst increases the rate of reaction more times than the rate of reaction before adding the catalyst and gives directly product that wants .

Hence, option A is true.

A.The test tube that stops bubbling first contains the catalyst.