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

Suppose a pair of chemical compounds a and b can react in two different ways: a + b -> c reaction 1 gives product c. a + b -> d reaction 2 gives product d. the following facts are known about the two reactions: . reaction 1 is endothermic and reaction 2 is exothermic. if a reaction vessel is charged (filled) with a and b , then at first d is produced faster than c. use these facts to sketch a qualitative reaction energy diagram for both reactions. note: because these sketches are only qualitative, the energies don? t have to be exact. they only have to have the right relationship to each other. for example, if one energy is less than another, that fact should be clear in your sketch.