Rate of change from graphs

A student carries out an enzyme-controlled reaction. They measure how the mass of substrate mg changes over time.

What should a graph of their results look like?

A

Explanation

When you draw a graph:

•The independent variable should be on the x-axis.

•The dependent variable should be on the y axis.

•The shape of the line of best fit depends on the trend shown by the data.

In this experiment:

•The independent variable is time.

•The dependent variable is the mass of the substrate.

•The trend shown by the data is linear, which means a straight line of best fit should be drawn.

Answer the question?

1. 0.33

2. B

To work out the units, substitute the y and x units into the same formula:

Rate of change units = change in y/change in x

Rate of change units = g dm*-3/s = g dm*-3 s*-1

Answer the followung questions

1. 0.03. 2. g/s or g s*-1

Explamation of q1 continued:

3.Calculate the change in y

2.2 - 1.1 = 1.1

4. Calculate the change in x

42 - 16 = 26

5. Change in y = 1.1, and change in

x = 26

Substitute these into the following formula:

Rate of change = change in x =

1.1/26 = 0.04230…

= 0.04 (2 d.p)

Q2 explamation:To work out the units, substitute the y and x units into the same formula:

Rate of change units =

change in y/ change in x

Rate of change units = g/s =

g s*-1

Answer the question:

To predict what the concentration of the product will be at 60s, the student should extend the line of best fit. This is called extrapolation.