Properties of Acids and Bases Lab by hcj

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									Properties of Acids and Bases
Identification and Classification Part II: Data and Post-Lab Questions
(introduction provided as hand-out and may be printed online)
Possible Heading (name, date, period, lab group) Data Table A Data Table B Lab Technique (including safety) Participation/Discussion for pre- and post-lab Reading Questions Post-lab Questions Conclusion Summary (1/2 sheet done in class) Total 1 2 2 4 2 2.5 8.5 2 24 Student assessment Teacher assessment

Data Table A: Classifying Acids and Bases
Test Property  1 hydrochloric acid 2 acetic acid Solution 3 distilled water 4 ammonia 5 sodium hydroxide

litmus paper (red) litmus paper (blue) phenolphthalein pH test paper universal indicator reaction with Mg conductivity

Data Table B: Neutralization Reactions of Acids and Bases
hydrochloric acid # drops NaOH added (trial 1) (5 drops acid) # drops NaOH added (trial 2) (5 drops acid + 5 drops water) Reading Questions (use the reading provided and the textbook ch. 19): acetic acid

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1. (0.5 pt) What is the relationship between conductivity and weak/strong acids and bases? 2. (0.5 pt) What are the three indicators used in this lab? Describe each. 3. (0.5 pt) What is pH? What is the scale of pH? 4. (0.5 pt) How is the reactivity of metals used to compare the relative acidity of a solution? 5. (0.5 pt) What is a neutralization reaction called? What does it produce? Post-Lab Questions 1. (0.5 pt) Use the results of the conductivity test to identify each solution in Part A as a strong electrolyte, weak electrolyte, or nonelectrolyte. HCl: CH3COOH: NH3: NaOH: 2. (0.5 pt) Which solutions in Part A reacted with magnesium metal? Write a balanced chemical equation for the reaction of each acid in Part A with magnesium

3. (0.5 pt) Strong acids ionize completely in water to form ions and are thus strong electrolytes. In contrast, weak acids do not readily ionize in water—in fact, less than 1% of the molecules are probably ionized at any given time. Weak acids are therefore weak electrolytes. Classify each acid as either a strong or weak acid. Which reacted faster with magnesium metal, the strong acid or the weak acid?

4. (0.5 pt) Write chemical equations for ionizations of the strong and weak acids in water. Identify the common ion that is produced in acidic solutions.

5. (0.5 pt) How can litmus paper and phenolphthalein be used to tell whether a solution is an acid or a base? Be specific.

6. (0.5 pt) Use the combined results of the conductivity and indicator tests to identify the basic solutions in Part A. Classify each as a strong versus weak base.

7. (0.5 pt) Write chemical equations for the ion-forming reactions of the strong and weak bases in water. Identify the common ion that is produced in basic solutions.
4-4-08 part II of II

8. (0.5 pt) Compare the pH data for the solutions that you labeled as acids and bases. What pH values can be assigned to acids and bases, respectively?

9. (0.5 pt) Compare the pH values of strong versus wear acid and strong versus weak base solutions. How does pH vary with the “strength” of an acid or base, respectively?

10. (0.5 pt) Explain the color change observed for the indicator in the neutralization reaction of hydrochloric acid in Part B. What is pH range of the final solution?

11. a.) (0.5 pt) Write separate, balanced equations for the neutralization reactions of hydrochloric acid and acetic acid with sodium hydroxide.

b.) (0.5 pt) Use the stoichiometry of the balanced chemical equations to explain the number of drops of sodium hydroxide required for complete neutralization of the acids.

c.) (0.5 pt) Did the strong and weak acids require equal number of drops of sodium hydroxide? Explain.

d.) (1 pt) Did adding water to the acid solutions change the number of drops of sodium hydroxide required for neutralization? Explain.

12. (1 pt) Complete the following table to summarize the properties of acids and bases. Property Acids Bases Conductivity Litmus (red) Litmus (blue) Phenolphthalein Reaction with metals pH

4-4-08 part II of II

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