Acid Rain Lab Report
Collaborators: Julianne Rodgers, Logan Shytle, Christina Filippini, Samantha Smithers
Introduction
According to the EPA, "Acid rain is a broad term referring to a mixture of wet and dry deposition (deposited material) from the atmosphere containing higher than normal amounts of nitric and sulfuric acids." Acid rain is formed when gases, sulfur dioxide and nitrogen oxides, react in the atmosphere with water, oxygen, and other chemicals to form various acidic compounds, resulting in sulfuric acid and nitric acid. Both sulfur dioxide and nitrogen oxides enter the atmosphere naturally and anthropogenically. These gases enter the atmosphere naturally by way of volcanoes and decaying vegetation and anthropogenic sources such as being emitted from industrial sources, energy generation, and automobiles. Acid rain can be detrimental to ecosystems, particularly plant life. "Acid rain does not usually kill trees directly. Instead, it is more likely to weaken trees by damaging their leaves, limiting the nutrients available to them, or exposing them to toxic substances slowly released from the soil" (EPA). The purpose of this lab is to determine how different pH's of acid rain affect the growth and the appearance of grass.
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Hypothesis:
If water with different pH levels comes into contact with grass because of acid rain, the water with the most acidic pH level (1.5) will damage the grass the most potentially killing it because the grass will be weakened by the most acidic water, while the water with the least acidic pH level (6) will damage the grass the least and actually allow for the grass to grow.
Parts of the Experiment:
Experimental Group: Bottle B and Bottle C -pH of 3 and 1.5 respectively
Control Group: Bottle A-pH of 6 (Regular Water)
Independent Variable: the pH level of the water
Dependent Variable: The appearance and the growth of the grass
Control: Amount of sunlight, temperature, the amount of water given to each plant, the amount of time each plant was exposed to the "acid rain"
Control Group: Bottle A-pH of 6 (Regular Water)
Independent Variable: the pH level of the water
Dependent Variable: The appearance and the growth of the grass
Control: Amount of sunlight, temperature, the amount of water given to each plant, the amount of time each plant was exposed to the "acid rain"
Materials:
- 3 two-liter bottles, halfway cut open
- Grass planted in each of the two liter bottles, for this experiment the same grass that was used in the Erosion Lab was used.
- Graduated Cylinder
- Water with a pH of 6, 3, and 1.5 (pH changed by Mr. Gunsher)
- Scissors
- Ruler
Methods:
1. Label bottles "A", "B", "C"
2. Trim the three bottles of grass to the same height. In this particular experiment the three bottles of grass were trimmed to 2 inches.
3. Record observations of the grass
4. Find the pH of the three different waters to be sure there is one with a pH of 6, 3, and 1.5
5. Pour: 100mL of the water with a pH of 6 into bottle A, 100mL of the water with a pH of 3 into bottle B, 100mL of the water with a pH of 1.5 into bottle C
6. Repeat this process every other day for two weeks
7. After two weeks, record observations of the grass including appearance and growth
2. Trim the three bottles of grass to the same height. In this particular experiment the three bottles of grass were trimmed to 2 inches.
3. Record observations of the grass
4. Find the pH of the three different waters to be sure there is one with a pH of 6, 3, and 1.5
5. Pour: 100mL of the water with a pH of 6 into bottle A, 100mL of the water with a pH of 3 into bottle B, 100mL of the water with a pH of 1.5 into bottle C
6. Repeat this process every other day for two weeks
7. After two weeks, record observations of the grass including appearance and growth
Data:
Data Analysis:
At the start of the experiment, all three bottles of grass were cut to two inches high in order to create an even starting point. Bottle A, the control group, received 100mL of water with a pH of 6 every other day for two weeks, bottle B received 100mL of water with a pH of 3 every other day for two weeks and bottle C received 100mL of water with a pH of 1.5 every other day for two weeks. After two weeks of "acid rain" every other day, bottle A grew 1 1/2 inches, bottle B grew 2 inches, and bottle C did not grow at all. These results show that the least acidic water does not necessarily equate to the most growth as the hypothesis had predicted. In fact, the data shows that a small amount of acid in water, specifically with a pH around 3, causes the most plant growth. The roots of the grass in bottle B were the longest out of all three bottles, which also showed that bottle B had the most growth. Bottle C had the shortest, and driest, roots of the three bottles, which would contribute to it having the least amount of growth.
The color of the grass also changed after two weeks of "acid rain". At the beginning of the experiment all three bottles of grass were a bright green color, whereas after two weeks the top of the grass in bottle C was brown and the grass was much thinner than it had been at the beginning. The color and thickness of the grass in bottles A and B did not change after the two weeks of "acid rain".
Another group in the class did the experiment of Marigolds. The group used three different marigold plants with the same three different pH levels of water that were used in this particular experiment. It appears from that data that the results of the marigolds were similar to that of the grass. The water with the highest pH was most damaging to the plant whereas the water with a pH of 3 seemed to increase growth more than the water with a pH of 6 did.
The color of the grass also changed after two weeks of "acid rain". At the beginning of the experiment all three bottles of grass were a bright green color, whereas after two weeks the top of the grass in bottle C was brown and the grass was much thinner than it had been at the beginning. The color and thickness of the grass in bottles A and B did not change after the two weeks of "acid rain".
Another group in the class did the experiment of Marigolds. The group used three different marigold plants with the same three different pH levels of water that were used in this particular experiment. It appears from that data that the results of the marigolds were similar to that of the grass. The water with the highest pH was most damaging to the plant whereas the water with a pH of 3 seemed to increase growth more than the water with a pH of 6 did.
Conclusion:
The data collected from this experiment supports part, but not all, of the hypothesis "If water with different pH levels comes into contact with grass because of acid rain, the water with the most acidic pH level (1.5) will damage the grass the most potentially killing it because the grass will be weakened by the most acidic water, while the water with the least acidic pH level (6) will damage the grass the least and actually allow for the grass to grow the most". The data supports the hypothesis because it is true that the most acidic water, with a pH level of 1.5, damages plants more than the other pH levels tested. However, the data disproves the hypothesis when it says that water with a pH of 6 will allow for the most growth. The data showed that a pH of 3 actually helped the plants to grow the most. This means that while acid rain is bad if the pH is low, it could be beneficial if it was around a pH level of 3.
To make this experiment more accurate, it could be conducted for a longer period of time in order to determine whether the water with a pH of three would continue to help plant growth or if it would eventually stop helping the plant and start harming it.
In reality, knowing the effects of acid rain is important. If the problems that it can cause, such as destruction of plant growth, are not known there will be no motive to fix the problem. If plants in an ecosystem are damaged, it could in the end affect the entire ecosystem because everything is connected. To reduce acid rain in the environment, sulfur dioxide and nitrogen oxides emissions must be reduced. While some of these gases come into the atmosphere through natural ways, such as by volcanoes, there are anthropogenic sources that can be reduced. For example, cars and industrial centers need to be created so that they do not release so much emission and so that they burn fuel more efficiently. If this can be done there would be less acid rain in the environment, allowing for healthier plants within ecosystems.
To make this experiment more accurate, it could be conducted for a longer period of time in order to determine whether the water with a pH of three would continue to help plant growth or if it would eventually stop helping the plant and start harming it.
In reality, knowing the effects of acid rain is important. If the problems that it can cause, such as destruction of plant growth, are not known there will be no motive to fix the problem. If plants in an ecosystem are damaged, it could in the end affect the entire ecosystem because everything is connected. To reduce acid rain in the environment, sulfur dioxide and nitrogen oxides emissions must be reduced. While some of these gases come into the atmosphere through natural ways, such as by volcanoes, there are anthropogenic sources that can be reduced. For example, cars and industrial centers need to be created so that they do not release so much emission and so that they burn fuel more efficiently. If this can be done there would be less acid rain in the environment, allowing for healthier plants within ecosystems.
Citations:
"What Is
Acid Rain?" EPA. Environmental Protection Agency, n.d. Web. 30 Apr.
2015. <http://www.epa.gov/acidrain/what/index.html>.
"Effects of Acid Rain - Forests." EPA. Environmental Protection Agency, n.d. Web. 01 May 2015. <http://www.epa.gov/acidrain/effects/forests.html>.
"Nitrous Oxide Emissions." EPA. Environmental Protection Agency, n.d. Web. 01 May 2015. <http://www.epa.gov/climatechange/ghgemissions/gases/n2o.html>.
"Effects of Acid Rain - Forests." EPA. Environmental Protection Agency, n.d. Web. 01 May 2015. <http://www.epa.gov/acidrain/effects/forests.html>.
"Nitrous Oxide Emissions." EPA. Environmental Protection Agency, n.d. Web. 01 May 2015. <http://www.epa.gov/climatechange/ghgemissions/gases/n2o.html>.