Chapter 6- Biochemistry

Name ______Period______Date______

Chapter 6- Biochemistry

Lab: pH of Common Substances

Pre-lab Questions:

1. Why must you use clean glassware in experiments involving pH? ______

2. What does pH measure? ______

3. What is a neutral solution? ______

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4. Is a pH of a strong base higher or lower than the pH of a weak base? ______

5. Is the pH of a strong acid higher or lower than the pH of a weak acid? ______

6. Name the products of a neutralization reaction. ______

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Investigations:

Part A: pH of Common Substances

1. pH of Common Substances

Substances / Color of Blue Litmus Paper / Color of Red Litmus Paper / pH Determined from pH Test Paper
Orange Juice
Vinegar
Milk
Egg White
Baking Soda
Ammonia Water

2. Using the data from table 1, place the substances that are listed onto the pH scale according your determined pH value. Be sure to both circle the value and label the substance.

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Strong……………….weak……………………neutral…………….weak…………….strong

Acids Bases

Part B: Analysis and Conclusions

3. Which of the solutions were acidic?______

4. Which of the solutions were basic? ______

5. Which of the test solutions is the strongest acid? ______

6. Which of the test solutions is the strongest base? ______

7. Which type of pH indicator is useful in determining the exact pH of a solution? ______

8. If you had to choose one indicator to use in a series of experiments, which one would you pick? Explain your choice.

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9. Suppose you are manufacturing a certain type of cosmetic. You know that it can be slightly acidic, but it should not be strongly acidic. Which of the indicators you have studied will help you determine the degree of acidity? Explain your answer.

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