Question

A student made a graph plotting the progress of a reaction over time. The student forgot to label the y-axis of the graph.

A graph is shown with two graph lines. One graph line starts at a higher position on the y axis and slopes downwards towards the right. The other graph line starts at a lower position on the y axis and slopes upwards towards the right. The two graph lines stop short of intersecting each other and continue as separate lines which gradually become straight and parallel to the x axis. A vertical line is shown at a point where the two graph lines finally became parallel to the x axis. This vertical line is labeled equilibrium. The title on the x axis is Time and an arrow pointing towards the right is shown above Time. The title on the y axis is left blank.

What best explains the label that the student should use on the y-axis? (5 points)

Group of answer choices

Amount, because as the amount of product decreases, the amount of reactant increases over time.

Reaction rate, because forward and backward reaction become equal at equilibrium.

Amount, because the amounts of reactants and products become constant after equilibrium is reached.

Reaction rate, as the rate of forward reaction increases and rate of backward reaction decreases over time.

Answer 1

Amount, because the amounts of reactants and products become constant after equilibrium is reached. Option C

The two graph lines in the provided graph description begin at different points on the y-axis and ultimately align to form a parallelogram with the x-axis, signifying the establishment of equilibrium.

Reactant and product concentrations stay constant at equilibrium, and their amounts don't vary over time. As a result, designating the y-axis as "Amount" would appropriately depict the graph's behavior during the establishment of equilibrium.

Answer 2

C

Step-by-step explanation:

Recall that, at equilibrium, the concentration of the reactants and products stop changing because both the forward and reverse reaction rates are equal.

Therefore, Choice C is correct.

Choice A is incorrect because there is no indication that the upper line describes the products and the lower line describes the reactants.

Choice B is incorrect because the statement, while true, is not reflected by the graph. (The two lines after equilibrium are not at the same y-value.)

Choice D is incorrect because the forward reaction rate generally decreases as time increases due to the decrease in reactant concentration(s).