Question

Experiment 1: Determining the Chemical Formula for Copper Gluconate The experiments in this lab use a compound named copper gluconate. This compound can be formed when gluconic acid (C6H12O7) and copper solutions react with copper (II) carbonates or copper hydroxide. Copper gluconate has a variety of uses and applications. For example, copper gluconate is used as a primary ingredient in the breath mint Certs®. It is also used as a source of copper in nutritional supplements. Your task will be to determine the chemical formula of the compound by isolating the copper and determining the molar ratio of copper and gluconate in the compound. Figure 3: Certs® Figure 3: Certs® Materials: 1 g Copper gluconate 10 mL 0.5% Salt, NaCl 10 mL Graduated cylinder Scale (1) 50 mL Beaker 250 mL Glass beaker 2 Aluminum washers Sterno® Ring stand Ring for ring stand Stir rod Matches Cupcake wrapper *Oven *Hot pad or towel *Baking pan *20 mL Distilled Water *Kitchen tongs *You must provide Procedure Put the 250 mL beaker on the scale and tare the scale. Measure 1.0 g of the copper gluconate in the beaker on the scale. Record the exact mass in the Data section below. Use the graduated cylinder to measure and pour 10 mL 0.5% NaCl into the beaker with the copper gluconate. You may need to gently swirl the solution if all the copper gluconate does not immediately suspend into the solution. Add two aluminum washers to the solution. Fasten the small ring approximately 6 - 10 inches up on the ring stand and place the beaker on the ring Place the Sterno® directly beneath the beaker. Remove the inner cap on the Sterno® and ignite the inner contents with the matches. Heat the beaker until solution clears. Your solution may not turn completely clear, but some color change should be evident. Alternatively you can also determine when the reaction is complete by looking for the formation of gas bubbles on the surface of the washers. When the formed gas bubbles are gone, then the reaction is complete. Note: Carefully monitor the set-up while the Sterno® is in use. You may need to adjust the height of the ring/beaker to ensure that the beaker is heated enough; and, to avoid exposing the beaker from high temperatures. **Carefully observe the set-up you choose!! Do not leave the beaker unattended while exposed to the Sterno®. Plastic beakers should never be used with heat.** Carefully remove the beaker from heat, and use forceps to replace the lid on the Sterno®. Decant (pour) the clear liquid into a 50 mL beaker. When all that remains in the original beaker are the copper plated washers, rinse the washers with distilled water and decant the remaining liquid, being careful not to lose any copper, into a container. This water can be disposed of down a sink drain. Repeat this process three times. Remove the first washer and use the stir stick to scrape the copper into the metal cupcake wrapper. Rinse the washer with distilled water to be sure all copper is recovered into the wrapper. Repeat the process for the second washer, scraping the copper into the same wrapper. Place the wrapper on a baking pan and put it in the oven at 115 °C (239 °C) to dry the product. Monitor the wrapper and contents and use a hot pad or towel to carefully remove them from the oven after 45 minutes, or after all of the water has evaporated. After the wrapper has cooled to room temperature, empty the dried copper from the wrapper onto the scale and weigh the final mass.

Why is it important in this experiment to be accurate in all your measurements?

List the measurements you will take in this experiment.

What chemical wastes are produced in this reaction?

Record the mass in the Data section below.

Data: Mass of copper gluconate (initial, see Step 2): _____________________

Mass of copper (final; see Step 13): _____________________

Calculations Mass of copper recovered:

Moles of copper :

Mass of gluconate:

Moles of gluconate:

Chemical formula:

1. What is the chemical formula of copper gluconate?

2. List two sources of error in the experiment and explain the impact they had on the results.

3. Create a pie chart showing the percent composition for each element in the compound copper gluconate, clearly label each element and the percentage.

4. Copper chloride can be used as a source of copper for this experiment, but copper gluconate is preferred due the fact that it is a “green” compound. Discuss the environmental

Answer 1

Mass of copper gluconate: 1.9g

Mass of copper: 0.6g

Moles of copper:

Mass of gluconate: 1.9g-0.6g=1.3g

Moles of gluconate:

Chemical formula:

The gluconate is (C₆H₁₁O₇^-)

The formula from you experiment is

1. What is the chemical formula of copper gluconate?

2. List two sources of error in the experiment and explain the impact they had on the results.

--->You did not wait until the reaction was completed, this could affect the amount of Copper you get at the end.

---->In th rinse step you may loose copper, and also it could affect the copper recovery.

3. Create a pie chart showing the percent composition for each element in the compound copper gluconate, clearly label each element and the percentage.

4. Copper chloride can be used as a source of copper for this experiment, but copper gluconate is preferred due the fact that it is a “green” compound. Discuss the environmental

Copper gluconate is a dietary sumplement thus, this compound is biodegradable. Several of the copper salts are toxic and very persisten in the environment.