Titration and Balancing Equations Questions

CHM-101L Titrations

Before beginning this activity, watch the videos “Titration Explained” and “Titration Math,” located in the topic materials.

Go to the website “Determination the Molarity of an acid or Base Solution,” through the link provided in the topic materials, and perform a strong acid versus strong base titration using the following parameters:

Titration #1 Trials A & B

1. Select type of reaction: strong acid versus strong base
2. Fill the burette with: base
3. Select the acid and base: HCl as the acid and NaOH as the base.
4. Select the indicator: phenolphthalein. (The indicator will change color when all the acid in the analyte is neutralized, this point is referred to as the endpoint of the titration. When using phenolphthalein there will be a colorless to pink change that occurs.)

In the table below, record the molarity and the volume of the HCl acid (given on the right of the Erlenmeyer flask on the screen) in the column labeled Titration #1 Trial A.

1. Perform the titration by adding small amounts of base (using the slider). As the pink color begins to persist in the reaction flask, slow down the addition of base to single drops at a time.

When one final drop leads to a permanent pink color in the reaction flask, stop the addition of base and record the total volume of base (final volume) in the burette in the table below.

1. Using the skills learned in the Titration Math video, calculate the molarity of the base and record in the table.

Hit the reset button and perform a second trial (B) of this titration repeating steps 1 through 6, once again using HCl as the acid and NaOH as the base.

Titration #2 & Titration #3

Complete two additional titrations, this time utilizing different acids and bases than those used in titration #1. In titration #2, keep the base as NaOH, but select H2SO4 as the acid. In titration #3, select HCl as the acid and use Ba(OH)2 as the base. Repeat steps 1 through 6 substituting these new selections for the acid and base to be used.

Data:

 Titration #1 Trial A Titration #1 Trial B Titration #2(H2SO4 + NaOH) Titration #3(HCl + Ba(OH)2) (HCl + NaOH) Molarity of acid 0.1419 M 0.1582 M 0.1227 M 0.2157 M Volume of acid 25.00 mL 25.00 mL 25.00 mL 25.00 mL Volume of base used to reach the endpoint 18.88 mL 19.38 mL 9.08 mL 10.3 mL Molarity of base

Molarity of Base Calculations

 Titration Show work ↓ NaOH: Titration #1 Trial A NaOH: Titration #1 Trial B NaOH: Titration #2 Ba(OH)2 : Titration #3

Lab Questions:

1. Balance the following equations:
1. # HCl + # NaOH # NaCl + # H2O
2. # H2SO4 + # NaOH # Na2SO4 + # H2O
3. # HCl + # Ba (OH)2 # BaCl2 + # H2O
2. How did the molarity calculations for Titration #1 Trials A and B compare? Were the values similar? Were they different? Explain why this would occur even if there were different volumes of acid and base used in each trial.

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1. Compare the volume of base needed to reach the endpoint in each titration. How did the amount of base needed in titration #1 compare to that of the base needed in titrations #2 and #3?

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1. Referencing your answer to question 3, explain why there were differences in the volumes of base. What about the formulas of the acids and bases used in each titration and the molar ratios of acid to base determined in the balanced equation affect the outcome?

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