Question

You want to test how the mass of a reactant affects the speed of a reaction.

Which of the following is an example of a controlled experiment to test this?
A) The mass of all the reactants is kept the same, and the mixtures are allowed to react for different amounts of time
B)The mass of all reactants is varied, and the time it takes the reaction to finish is measured
C)The mass of one reactant at a time is varied, and the time it takes one reactant to finish is measured
D)The mass of one reactant and the temperature of the reaction mixture are increased until reaction is finished

Answer 1

The best controlled experiment to test how the mass of a reactant affects the speed of a reaction is to vary the mass of one reactant at a time and measure the time it takes for the reaction to complete, while keeping other conditions constant.

Step-by-step explanation:

To test how the mass of a reactant affects the speed of a reaction, a controlled experiment is necessary. The best option among those provided would be:

C) The mass of one reactant at a time is varied, and the time it takes for the reaction to finish is measured.

This is because it isolates the variable of mass and directly measures its effect on the reaction speed while keeping other factors constant. The independent variable in this experiment would be the mass of the reactant, and the dependent variable would be the time it takes for the reaction to complete. To ensure a controlled experiment, you would maintain constant conditions such as temperature, concentration of other reactants, surface area of the reactants, and absence of a catalyst. This ensures that the only variable affecting the speed of the reaction is the mass of the specific reactant being varied.