Investigation Of The Effects Of Acid Rain

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Samuel Turner

Mr. Eichbauer

IB Chemistry II – Period 6

16 February 2015

Investigation of the Effects of Acid Rain

Background Information

Acid rain is when there is a mix of wet and dry deposited material in the atmosphere that have higher levels of nitric and sulfuring acid. These chemicals formed can be from natural causes, like volcanoes and the decay of vegetation, or man made causes like fossil fuel combustion. Acid rain can be measured using the pH scale, and will always be on the lower end of the spectrum because of its acidity. Water has a pH of 7, but the acidity of normal rain tends to be slightly more acidic. Acid rain can be very detrimental to the biotic environment that it comes in contact with as well as the non-living matter in the area. In the following experiment, the student will use a variation of nitric acid solutions with different molarities to see the effects that they have on copper. For the control, the same tests will be done with rainwater with a known pH. After the experiment the concentration of the solutions can be converted to pH using the equation pH = -log[H+]. After converting this the student will show a display of the data using a graph that shows how the solutions affect the corrosion on the metal by using the change in its mass.

Purpose of the Investigation

Observe: How nitric acid with different concentrations can affect the corrosion of copper.

Evaluate: How pH of a solution can affect the corrosion of copper represented in a graphical form.

Variables

Controlled: Volume of acid, the amount of time the copper is exposed to the solution

Independent: The molarities of the acid

Dependent: Change in mass of the copper

Control Group: rain water the copper is exposed to

Materials

12 strips of copper
pH meter (+ 0.01)
Digital scale (+ 0.01)
graduated cylinder (±0.05 mL)
experimental setup diagram
60mL of rain water
60mL of 0.5 M HNO3
60mL of 1.0 M HNO3
60mL of 1.5 M HNO3
4 petri dishes

Experimental Process

1. Measure out 20mL of rain water and place it in the first petri dish labeled #1 2. Record the pH of the water
3. Measure the initial mass of a copper strip
4. Place the copper into the rain water for 15 minutes, then remove the copper, and measure its mass after exposure. 5. Subtract the final mass from the initial mass of copper and record it 6. Repeat the process 2 more times for a more precise result 7. Repeat steps 1-6 using the 0.5 M Nitric Acid

8. Repeat steps 1-6 using the 1.0 M Nitric Acid
9. Repeat steps 1-6 using the 1.5 M Nitric Acid

Recording Data
Table One: Dish #1
H2O

Trial 1

Trial 2

Trial 3
pH of Water Sample (±0.01 g)

Initial Mass of Copper (±0.01 g)

Final Mass of Copper (±0.01 g)

Change in Mass

Table 2: Dish #2
0.5 M HNO3

Trial 1

Trial 2

Trial 3
Initial Mass of Copper (±0.01 g)

Final Mass of Copper (±0.01 g)

Change in Mass

Table 3: Dish #3
1.0 M HNO3

Trial 1

Trial 2

Trial 3
Initial Mass of Copper (±0.01 g)

Final Mass of Copper (±0.01 g)

Change in Mass

Table 4: Dish #4
1.5 M HNO3

Trial 1

Trial 2

Trial 3
Initial Mass of Copper (±0.01 g)

Final Mass of Copper (±0.01 g)

Change in Mass

Data Processing

Each of the molarities of the nitric acid solutions should be converted into pH using the equation pH = -log[H+]. The data of these conversions can be recorded here:

Molarity of Solution
0.5 M HNO3
1.0 M HNO3
1.5 M HNO3
pH Value

Using the values above create a graph to correspond with the pH and the change in pH from the control group of rain water. A line best fit should be shown to show the average change in mass in correspondence with pH of a solution.
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