Effect of PH of Acid Rain on the Degradation of Limestone Ibi Biology Lab Report

Water can become substantially acidic when certain chemicals are mixed into it. These chemicals are the by-products of certain industrial processes, which mix with water vapor, thereby entering the water supply through rain.

Planning A & B

Higher Level Biology

Effect of pH of Acid Rain on The Degradation of Limestone

Background

Normal rain has a pH of 5.6. This acidity is due to the reaction of water molecules that form rain droplets with carbon dioxide (CO2), resulting in the formation carbonic acid (H2CO3).

The reaction occurs as follows:

Carbon Dioxide + Rainwater → carbonic acid

CO2 (g) + H2O (l) → H2CO3 (aq)

However, water can become substantially acidic when certain chemicals are mixed into it. These chemicals are the bi-products of certain industrial processes, which mix with water vapor, thereby entering the water supply through rain. Organisms all need water to function properly, but that water must have a certain pH range limit. Plants in general are affected by acidic water when their roots take it in. If there is too much acid in the water supply, the organism might die.

The purpose of the lab is to study the effect of acid rain on the germination of seeds. Bean plants produce beans, the seeds which are to be used throughout the experiment.

Research Question

What is the effect of acid rain (sulfuric acid) on bean germination in cotton?

Hypothesis

Acid rain hinders bean germination. The lower the pH of the water the less likely a seed will germinate. In some cases, if germination occurs, the seed's green root will be underdeveloped with regards to the time spent germinating.

Variables

Dependant Variables

• Germination of beans and length of the root

Independent Variables

pH of solutions:

• Beaker 1 contains 100ml of distilled water; it is placed in beaker 1 (pH=7)
• Beaker 2 contains 99ml of distilled water and 1ml of 0.0001mol.dm-3 of hydrochloric acid (pH=6)
• Beaker 3 contains 99ml of distilled water and 1ml of 0.001mol.dm-3 of hydrochloric acid (pH=5)
• Beaker 4 contains 99ml of distilled water and 1ml of 0.01mol.dm-3 of hydrochloric acid (pH=4)
• Beaker 5 contains 99ml of distilled water and 1ml of 0.1mol.dm-3 of hydrochloric acid (pH=3)

Controlled Variables

The control variables need to be constant in order to get valid and accurate results.

• Temperature (maintained at room temperature)
• Pressure applied to the seeds
• Water abundance
• Sterilization of Petri dish using anti-bacterial soap

Material Required

• 50 beans
• 5 Petri dishes
• Sulfuric acid
• 5 beakers
• Distilled Water
• Cotton
• Pipette

Controlling the Variables

Sunlight is not needed for seed germination. The seeds will germinate easily in the dark. However, beans need to be maintained at a temperature between 10 and 30°C in order to germinate.

Water is important for the germination of all the beans; this is why it is favorable that all the Petri dishes be filled with an abundant amount of water.

The beans should be relatively of equal size. This is because if beans of different sizes were chosen, the final results would not be valid since the effect studied may vary with bean size.

If a certain pressure threshold is surpassed a bean may break or its development may be hindered, therefore the final results may be changed and the beans should be handled rather delicately.

The type of seed used is a contributing factor in the experiment. Certain seeds may have a tolerance to acidic soil and hence they are able to germinate normally. Hence the conclusions and results of the experiment should only be applied to the type of seeds used.

Cotton is used instead of soil for three reasons. Firstly, soil is too messy compared to the use of cotton and it will be harder to recover the beans for analysis. Secondly if the beans were planted in soil, their seed coat might become damaged due to a rupture of some sorts. Thirdly, in the case of a rupture and the presence of micro-organisms in the soil, the bean would be decomposed by the organisms thereby affecting the final results.

Procedure

Preparing theSolutions

5 solutions need to be prepared. Use the pipette to introduce a certain volume of 0.0001mol.dm-3, of 0.001mol.dm-3, of 0.01mol.dm-3 of hydrochloric acid solution and of 0.1mol.dm-3 of hydrochloric acid solution into each beaker as follows:

Beaker 1 contains 100ml of distilled water; it is placed in beaker 1 (pH=7)

Beaker 2 contains 99ml of distilled water and 1ml of 0.0001mol.dm-3 of hydrochloric acid (pH=6)

Beaker 3 contains 99ml of distilled water and 1ml of 0.001mol.dm-3 of hydrochloric acid (pH=5)

Beaker 4 contains 99ml of distilled water and 1ml of 0.01mol.dm-3 of hydrochloric acid (pH=4)

Beaker 5 contains 99ml of distilled water and 1ml of 0.1mol.dm-3 of hydrochloric acid (pH=3)

1. Mark the Petri dishes 1 through 5
2. Rinse the dishes and the bean seeds thoroughly with antibacterial soap
3. Place a relatively thick layer of cotton in each dish in order to completely fill the whole dish
4. Place the required volume of solution from each beaker into its corresponding Petri dish in order to fill it completely
5. Place 10 beans into each dish and make sure to spread them out in the cotton, make sure all 50 beans are relatively of same size
6. Cover the Petri dish with a cap and leave undisturbed in a dark location with a temperature that varies between 20 and 30°C
7. Leave for 14 days
8. After waiting period is over, remove cap, gently remove seed without ripping it apart from its root (if any) and measure. Place the data in a table that depicts the beaker number, germination (if present) and the length of the root (if present). Calculate the average length of the seed roots in each dish and graph the data against the concentration of acid in each solution. Draw a graph of the length of the root against the pH of the solutions and comment on the graph and draw your conclusions.

Resources

http://wow.osu.edu/experiments/plants/germination.html