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UNSW : UNSW Atmosphere Study Guide
Atmosphere Study Guide 38 BACKGROUND INFORMATION Acid rain occurs when the rain falling from clouds picks up toxic chemicals such as nitrous oxide and sulphur dioxide that have been pumped into the atmosphere by factories. These chemicals make the rain acidic, which can cause many harmful effects when the rain lands on Earth. For example, acid rain can pollute lakes and rivers, harm plants and animals, change the chemical balance of soil and destroy buildings and statues. It is the effect that it has on statues and building made of limestone that we are going to investigate today. AIM To examine the effect of acid on limestone. MATERIALS • A few pieces of limestone • A dropper bottle with diluted hydrochloric (HCl) acid • A dropper bottle with tap water • Two petri dishes • Universal indicator and colour chart METHOD 1. Measure the pH of the acid and record in the results table below (or a similar table in your work book). 2. Measure the pH of the tap water and record it in the results table. 3. Select two pieces of similar sized limestone and place one piece in each of the two petri dishes. 4. Label one dish ‘water’ and the other ‘acid’. 5. Place five drops of water on the designated limestone and observe what happens. Record your observations in the results table. 6. Place five drops of acid on the designated limestone and observe what happens. Record observations in the results table. 7. Rinse the limestone that had the acid on it in water and return both pieces of limestone to their original container. 8. Clean up the rest of the equipment. RISK ANALYSIS Complete the following table before you start the experiment. Risk Precaution Consequence Sharp broken glass Wear safety goggles so that acid does not splash in your eye RESULTS Fill in the table below as best you can, or create a similar table in your exercise book. Solution pH Observation when added to limestone Water Acid Experiment 1 ACID RAIN EXPERIMENT iSTOCKPHOTO Elaborate