CHEM 2115 Lab Report Experiment #11 Acids, Bases, Salts & Buffers Chem I Lab

1CHEM 2115 Lab Report Experiment #11 Acids, Bases, Salts & Buffers Chem I Lab

Section # Station # Date

A. Acid-Base Neutralization I. Describe your observations in the table below.

Observations

Solid residue

AgNO3 addition

Flame test

II. Write a balanced chemical equation for the neutralization reaction you observed.

B. pH Measurement I. Record the measured pH for the substances listed below.

Substance pH Substance pH Substance pH Lemon Juice Ammonia Baking soda Laundry Orange juice Aspirin detergent Dishwashing Buffered Milk detergent aspirin C. Acid-Base Indicators

Indicator Color in 0.05 M HCl Color in 0.05 M NaOH Methyl red Bromcresol green Phenolphthalein Methyl orange Methyl violet

I. Which indicator would be best in distinguishing between 0.05 M HCl and 0.05 M NaOH? Which would be the worst? Justify your answer.

D. Behavior of Salt Solutions

Salt Solution pH Sodium acetate Sodium carbonate Ammonium chloride Sodium chloride Boiled distilled water

I. Which ions exhibit significant Brønsted acid character? Brønsted base character? Are your results consistent the expected results based on the theory of hydrolysis? E. Buffers

Buffer Initial pH pH after adding HCl pH after adding NaOH Solution A Solution B Solution C Solution D Boiled water

I. Which solutions are able to buffer well against acid? Against base? Explain.

II. Are any solutions able to buffer well against both acid and base? Explain.

III. Do any solutions show little or no buffering ability? Explain.

IV. Write equations to show how a buffer made up of equimolar amounts of acetic acid, - CH3COOH, and acetate, CH3COO , would behave when (a) HCl is added and (b) NaOH is added.

V. At what point is a buffer solution no longer effective in resisting a pH change when a strong acid is added?