A student investigates the rate of catalytic decomposition of sodium hypochlorite solution:
2NaOCl(aq)→2NaCl(aq)+O2(g) 2\text{NaOCl(aq)} \rightarrow 2\text{NaCl(aq)} + \text{O}_2\text{(g)} 2NaOCl(aq)→2NaCl(aq)+O2(g)The student uses a flask connected to a gas syringe to collect the oxygen gas.
The student keeps the amount, in moles, of NaOCl\text{NaOCl}NaOCl in the solution constant at the start of each experiment.
State two properties of the solution that should be kept the same to ensure that the initial amount of NaOCl\text{NaOCl}NaOCl is the same in each experiment.
The student carries out the experiment five times using a different solid metal oxide each time to see how effective each is as a catalyst.
He records the time taken to collect 60 cm360\text{ cm}^360 cm3 of oxygen in the gas syringe.
| Solid | Time to collect 60 cm360\text{ cm}^360 cm3 of oxygen (seconds) |
|---|---|
| A | 95 |
| B | 14 |
| C | no oxygen collected |
| D | 158 |
| E | 36 |
Which solid does not seem to act as a catalyst?
Which solid is the most effective catalyst?
In the first experiment, the student added 1.50 g1.50\text{ g}1.50 g of solid A.
Describe what he could do with the contents of the flask at the end of the experiment to show that solid A was acting as a catalyst, and not as a reactant.
The student repeats the experiment using two new solids, V and W. This time, he records the volume of oxygen collected at 151515-second intervals.
The results are shown in the table below:
| Time (seconds) | Volume of oxygen collected for Solid V (cm3\text{cm}^3cm3) | Volume of oxygen collected for Solid W (cm3\text{cm}^3cm3) |
|---|---|---|
| 0 | 0 | 0 |
| 15 | 36 | 18 |
| 30 | 54 | 33 |
| 45 | 60 | 45 |
| 60 | 60 | 53 |
| 75 | 60 | 58 |
| 90 | 60 | 60 |
Calculate the average rate of oxygen production for Solid W during the first 30 seconds30\text{ seconds}30 seconds of the reaction.
Estimate the volume of oxygen collected after 50 seconds50\text{ seconds}50 seconds for Solid W.
Use the data to explain how it shows that the reaction is faster with Solid V than with Solid W.
