2. How will the results be presented? Would a trend graph show the results clearly? 3. State what you found out. This will be your conclusion.
25.2 Production of common gases
Production of carbon dioxide Carbon dioxide is produced by chemical reactions between acids and carbonates. Baking soda and marble chips are both made from carbonates.
Acid + Carbonate Activity Using baking soda and vinegar to produce carbon dioxide
Apparatus Bottle, balloon, vinegar, baking soda
Method 1. Fill a balloon with baking soda using a funnel. 2. Pour some vinegar into a bottle. 3. Put the neck of the balloon over the bottle opening. 4. Lift the balloon up so that the baking soda falls onto the acid. 5. A gas will be produced and this gas will fill the balloon. 6. Bubble some of this gas through limewater. This can be done by holding the neck of the balloon under the surface of the limewater and allowing the gas to slowly leave the balloon. If the gas produced is carbon dioxide it will turn the limewater milky.
Salt + Water + Carbon dioxide
Fig. 1 Making carbon dioxide.
The above activity is a good way to make carbon dioxide. It is difficult to measure the rate of reaction in this activity, however. In the activity on the next page, marble chips (calcium carbonate) and hydrochloric acid are reacted together to produce carbon dioxide. The equation for this reaction is:
According to the law of conservation of mass, the mass of the chemicals at the start of the experiment should be the same as the mass of the chemicals at the end of the experiment. However, carbon dioxide is a gas and it can escape from the flask. This makes the mass of the products appear to be less because the mass of the carbon dioxide produced is not included (see Figs. 2 and 3 on the next page). By measuring the amount of mass lost from the flask over a period of time it is possible to measure the rate of reaction.
