Problem
The problem of the lab is to determine which type of stone would be the best building material for a statue. The types of stones tested were red sandstone, granite, pea stone, and limestone.
Hypothesis
If granite is the best stone then the pH of the stone will increase because the vinegar will become less acidic when the stone gets dissolved.
Experimental Design
Identification of Variables:
The independent variable in the lab were the four types of stone. The four types of stone were red sandstone, granite, pea stone, and limestone. The dependent variable of the experiment was the acidity of the vinegar on the pH scale. The control was to have the stones in water. The control was used as a standard of comparison to compare the acidity of the stones to the stones in vinegar. Constants in the lab were the amount of rocks, the amount of water, the amount of vinegar, to use the same pH scale, and to use the same type of litmus paper.
Materials:
- Balance
- Containers
- PH Paper
- Graduated Cylinder
- Water
- Vinegar
- Limestone
- Red Sandstone
- Granite
- Pea Stone
Procedure:
- Get all materials
- Measure out 20 ml of water for the four containers for the control
- Put 10 g of each stone in the four containers with the water and record the pH in the data table.
- Measure the pH of the water with the stones in the container
- Get four more containers and fill them with 20 ml of vinegar
- Put 10 g of each stone in the four containers with the vinegar
- Take the pH of the vinegar with the stones in the vinegar and record the pH in the data table
- Leave the containers over night and find the pH of the vinegar and water for each stone and record the pH in the data table
Data Presentation:
| Control: 20 mL of water | Initial pH | Final pH | Change of pH |
| Red Sandstone | 7 | 7 | 0 |
| Granite | 7 | 7 | 0 |
| Pea Stone | 7 | 7 | 0 |
| Limestone | 7 | 7 | 0 |
| 20 mL of Vinegar | Initial pH | Final pH | Change of pH |
| Red Sandstone | 2 | 4 | 2 |
| Granite | 2 | 4 | 2 |
| Pea Stone | 2 | 5 | 3 |
| Limestone | 2 | 6 | 4 |
Written Results:
The initial pH for all of the stones in the control was a pH of 7. The final pH for all of the stones in the control was 7, which made the change of pH for each stone zero. The initial pH for the stones in the vinegar was 2. The final pH for the red sandstone was 4 making a change of 2. The final pH for granite was 4, which made the change of pH 2. Pea stones final pH was 5. The total change of pH for pea stone was 3. The final pH for limestone was 6 and that made the change of pH 4 for limestone.
Conclusion
The problem of the lab was the investigate the effect of acid rain on various building materials in order to make a recommendation to the town council as to the best material to use for a statue. The hypothesis of the lab was if granite were the best stone then the pH would increase because the vinegar will become less acidic if the stone gets dissolved. The data in the lab suggests that the hypothesis was incorrect. Granites initial pH was 2 and the final pH was 4. The change of pH was 2. The stone that increased the most was limestone. Limestone had an initial pH of 2 and a final of 6. The change of pH was 4 and limestone was the least acidic.
Validity:
The lab could have had a few errors. The first error could have been that the same amounts of stone were not in the containers. This could have meant that there would have been more stone to dissolve. The second error could have been that there was not the same amount of liquid in the containers. There could have been more vinegar in one of the containers that could have made the stone dissolve quicker. The third error could have been that the pH scale was read wrong.
