Titration

Titration of acetic acid: Fill the buret with 0.1 M NaOH. Put 0.1 grams acetic acid in the beaker with 50 mL water. Put phenolphthalein indicator in the beaker. Click on the stopcock and pull down to dispense the NaOH solution. Continue to the phenolphthalein end point.

How many moles of acetic acid are there based on the titration? What is the formula weight of acetic acid? How does this compare to the literature value?

Repeat the acetic acid titration, but do not add indicator. Instead, add 1 mL of NaOH at a time and record the pH and volume dispensed. Titrate to pH > 10 and graph pH versus volume dispensed. Determine the pKa of acetic acid from this graph.

Try the above exercises using citric acid. How does citric acid differ from acetic acid?

Titration of phosphoric acid: Make a graph of pH versus volume by titrating phosphoric acid. How many protons are there per molecule of acid? What are the observed pKa's?

Calorimetry

Find the calorimeter constant based on the manual directions. The calorimeter constant is randomly set and will differ for each run.

Heat of solution: Add 12.04 grams of ammonium sulfate in 200 mL water. Note the initial temperature. Click on the calorimeter to start the experiment. Record the temperature at each time displayed on the status bar. What is the maximum temperature change? What is the heat of solution?

Repeat the experiment with 13.21 grams of magnesium sulfate. What is different this time? What is the maximum temperature change and heat of solution?

Freezing point depression

Dissolve 0.2 moles of each compound in 100 mL water. Click on the beaker to start cooling. How does each compound change the temperature? What does this tell about the nature of each chemical?

Place an amount of table sugar in water and freeze it. What is the formula weight of table sugar?

Spectrophotometry

What wavelengths of light correspond to red, yellow, orange, green, blue , and violet?

Make a 0.2 M sample of copper sulfate. Run a wavelength scan and plot absorbance versus wavelength. How does this relate to the color of the sample?

Determine the extinction coefficient of each salt. Use this information to determine the concentration of an arbitrary solution.