Rate Calculations for Enzyme Activity Flashcards

All 6 cards in this deck

What is the formula for the rate of reaction when you know only the time taken for the reaction to finish?

Rate $= 1 \div$ time, with units s$^{-1}$.

What are the steps to calculate the rate of an enzyme reaction from the time taken for it to finish?
e.g. the reaction is complete after 50 s

1. Take the time in seconds: 50 s.
2. Divide 1 by the time: $1 \div 50$.
3. Rate $= 0.020$ s$^{-1}$.

What are the steps to calculate the rate of an enzyme reaction from the amount of product made?
e.g. 20 cm$^3$ of oxygen collected in 40 s

1. Note the amount of product: 20 cm$^3$.
2. Note the time taken: 40 s.
3. Divide amount by time: $20 \div 40 = 0.5$ cm$^3$/s.

How do you convert a rate in cm$^3$/s into cm$^3$/min?
e.g. a rate of 0.5 cm$^3$/s

Multiply by 60: $0.5 \times 60 = 30$ cm$^3$/min.

How do you find the rate of reaction from a straight-line graph of product formed against time?
e.g. a line through (0 s, 0 cm$^3$) and (20 s, 10 cm$^3$)

1. Choose two points on the line.
2. Rate = change in y $\div$ change in x: $10 \div 20$.
3. Rate $= 0.5$ cm$^3$/s.

On a graph of product formed against time, what does a flat (level) part of the line show?

The reaction has stopped — no more product is being made, e.g. because all the substrate has been used up.