1. A large quantity of dilute nitric acid was added to a 5.0g of marble powder in an evaporating

dish, which was placed on the pan of a balance.A chemical reaction occurs and calcium nitrate, carbon

dioxide and water are formed.

The mass of the dish, and its contents was recorded every half minute.

The results are shown in the graph below.

1. Write down the word equation for the reaction.
2. Explain why the mass of the dish and its contents lose mass.
3. What was the mass of the evaporating dish and its contents at the
   1. start of the experiment?
   2. end of the experiment?
4. What mass of carbon dioxide was produced during the experiment ?
5. When does the reaction seem to stop?
6. During which of these times in the experiment was the rate of reaction most rapid:
   1. 0 - 1.0 minutes?
   2. 1.0 - 2.0 minutes?
   3. 2.0 - 3.0 minutes?
7. On the graph sketch the curve you would expect if
   1. the acid used was much hotter. (Label it X)
   2. marble chips had been used instead of the powder.(Label it Y)
   3. more concentrated nitric acid was used.
8. If the amount of marble powder used was doubled how much carbon dioxide would be produced ?

2. Sam is investigating the reaction between marble chips and dilute hydrochloric acid.

The marble chips she uses has a mass of 5.0 g.

She also uses 50 cm³ of dilute hydrochloric acid in the experiment.

The temperature of the acid is 20 ^oC.

Look at the diagram. It shows the apparatus that Sam uses.

Sam writes down the mass of the marble chips and acid every two minutes.

Look at her results.

Here is the equation for the reaction.

Look at the results.

1. The mass of calcium carbonate and acid gets smaller during the experiment. Explain why. [1]

2. Sam knows that the reaction stops after twenty minutes. Explain how she can tell from her results. [1]

Sam does the experiment a second time. Again she makes just one change.

She uses marble powder instead of a lump.

3. Explain why the reaction is faster.Use ideas about collisions between particles. [1]

Sam now investigating the reaction between calcium and dilute hydrochloric acid.

The calcium metal she uses has a mass of 2.0 g.

She also uses 50 cm³ of dilute hydrochloric acid in the experiment.

The temperature of the acid is 20 ^oC.

She uses exactly the same apparatus as before.

When calcium reacts with hydrochloric acid calcium chloride and hydrogen are produced.

4. Write down the word equation for this reaction. [2]

Sam decides to test the gas. She decides to burn the gas with a lighted splint.

5.What will happen if she does this ? [1]

6.What is the name of the gas produced in this reaction ? [1]

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