Rates Of Reaction

Question 1

What does the gradient equal in a conc-time graph?

Answer 1

• Rate of the reaction.

Question 2

What is the shape of a zero order line?

Answer 2

• Straight line.

Question 3

What is the shape of a first order line?

Answer 3

• Downward curve with decreasing gradient over time. Constant half-life.

Question 4

What is the shape of a second order line?

Answer 4

• Also a downcard curve. Steeper at the start, but tailing off more slowly.

Question 5

What are the two ways of calculating ‘k’?

Answer 5

• k = ln2/t1/2 (half-life)
• k = rate/[A][B]

Question 6

What is the shape of a zero order reactant line in a rate concentration graph?

Answer 6

• horizontal straight-line with zero gradient.
• The intercept on the y-axis gives the rate constant k.
• The reaction rate doesn’t change with concentration.

Question 7

What is the shape of a first order reactant line in a rate concentration graph?

Answer 7

• Produces a straight-line graph through the origin.
• Rate is directly proportional to concentration by measuring the gradient of the straight line.

Question 8

What is the shape of a second order reactant line in a rate concentration graph?

Answer 8

• Produces an upward curve with increasing gradient.
• As this rate-concentration graph is a curve, the rate constant cannot be obtained directly from this graph.
• A graph of rate vs concentration squared can be plotted, the result is a straight line through the origin. The gradient of this straight line graph is equal to the rate constant k.