Some students design an experiment to investigate the effect of hydrogen peroxide concentration on the rate of oxygen production by the enzyme catalase. The apparatus collected oxygen gas in a gas syringe.

Method:

Use a stock solution of $25%25\%$ hydrogen peroxide to make dilution series solutions, including $5%5\%$ and $15%15\%$ hydrogen peroxide.
Set up a conical flask containing a fixed concentration and volume of celery extract (containing catalase) and add the hydrogen peroxide solution.
Record the volume of oxygen gas given off every $s20\text{ s}$ for $s80\text{ s}$ .
Repeat the experiment three times for each concentration.

Some of the results are shown in the tables below:

Table 1: Results for $5%5\%$ hydrogen peroxide

Time (s)	Trial 1 ( $cm3\text{cm}^3$ )	Trial 2 ( $cm3\text{cm}^3$ )	Trial 3 ( $cm3\text{cm}^3$ )	Mean ( $cm3\text{cm}^3$ )	Standard deviation
20	12	14	13	13.0	1.0
40	23	25	24	24.0	1.0
60	32	35	32	33.0	1.7
80	40	41	39	40.0	1.0

Table 2: Results for $25%25\%$ hydrogen peroxide

Time (s)	Trial 1 ( $cm3\text{cm}^3$ )	Trial 2 ( $cm3\text{cm}^3$ )	Trial 3 ( $cm3\text{cm}^3$ )	Mean ( $cm3\text{cm}^3$ )	Standard deviation
20	25	23	24	24.0	1.0
40	46	40	46	44.0	[ To be calculated ]
60	61	58	61	60.0	1.7
80	72	68	70	70.0	2.0

(i) State the independent variable in this investigation. (ii) Describe how a student could produce a $15%15\%$ dilute hydrogen peroxide solution from the $25%25\%$ stock solution.

(i) Calculate the standard deviation for the $s40\text{ s}$ result at $25%25\%$ hydrogen peroxide. Use the formula:

\sqrt{\frac{\sum(x - \bar{x})^2}{n - 1}}

Give your answer to 1 decimal place. (ii) Calculate the initial rate of reaction over the first $s20\text{ s}$ for the result at $5%5\%$ hydrogen peroxide. Include the appropriate unit.

Method:

Use a stock solution of $25%25\%$ hydrogen peroxide to make dilution series solutions, including $5%5\%$ and $15%15\%$ hydrogen peroxide.
Set up a conical flask containing a fixed concentration and volume of celery extract (containing catalase) and add the hydrogen peroxide solution.
Record the volume of oxygen gas given off every $s20\text{ s}$ for $s80\text{ s}$ .
Repeat the experiment three times for each concentration.

Some of the results are shown in the tables below:

Table 1: Results for $5%5\%$ hydrogen peroxide

Time (s)	Trial 1 ( $cm3\text{cm}^3$ )	Trial 2 ( $cm3\text{cm}^3$ )	Trial 3 ( $cm3\text{cm}^3$ )	Mean ( $cm3\text{cm}^3$ )	Standard deviation
20	12	14	13	13.0	1.0
40	23	25	24	24.0	1.0
60	32	35	32	33.0	1.7
80	40	41	39	40.0	1.0

Table 2: Results for $25%25\%$ hydrogen peroxide

Time (s)	Trial 1 ( $cm3\text{cm}^3$ )	Trial 2 ( $cm3\text{cm}^3$ )	Trial 3 ( $cm3\text{cm}^3$ )	Mean ( $cm3\text{cm}^3$ )	Standard deviation
20	25	23	24	24.0	1.0
40	46	40	46	44.0	[ To be calculated ]
60	61	58	61	60.0	1.7
80	72	68	70	70.0	2.0

(i) State the independent variable in this investigation. (ii) Describe how a student could produce a $15%15\%$ dilute hydrogen peroxide solution from the $25%25\%$ stock solution.

(i) Calculate the standard deviation for the $s40\text{ s}$ result at $25%25\%$ hydrogen peroxide. Use the formula:

\sqrt{\frac{\sum(x - \bar{x})^2}{n - 1}}

Give your answer to 1 decimal place. (ii) Calculate the initial rate of reaction over the first $s20\text{ s}$ for the result at $5%5\%$ hydrogen peroxide. Include the appropriate unit.

Planning

Question 15

Markscheme

Planning

Question 15

Markscheme

Planning

Question 15

Planning Questions

Planning

Question 15

Planning Questions