here is all the information i have from the lab: Measure and record the mass of
ID: 494539 • Letter: H
Question
here is all the information i have from the lab:
Measure and record the mass of a clean, dry crucible with its cover. Record this value to within 0.001 g.
After setting up we measured the crucible to weigh 31.353 grams
Obtain and record the copper chloride hydrate mass.
Obtain about one gram (1 ± 0.1 g) of the unknown copper chloride hydrate using a weigh paper.
Place the unknown copper chloride in the crucible. Use a spatula to carefully break up any large pieces of the substance by pressing the pieces against the wall of the crucible.
Measure and record the mass of the crucible with the compound. Record your data to within 0.001 g.
next we measure the mass of the copper chloride hydrate mass using the weigh paper. It came out with a mass of 1.045grams.
Next we put the copper chloride in the crucible
After that we measured them all together and it weighed 32.4 grams.
Place the crucible on the clay triangle. Tip the crucible lid slightly so that it does not fit snugly over the top of the crucible. Do not tip it towards the edge of the lab bench. Note: Escaping gases during heating could cause harm. Be careful with the components heated during the experiment.
6. Prepare to heat the sample.
Set up a Bunsen burner and ignite the burner away from you and the crucible.
Once lit, adjust the flame until a small blue flame is produced. Your instructor can help fine tune the settings.
Hold the burner in your hand and move the flame slowly back and forth underneath the crucible to gently heat the sample. Do not overheat the compound! The sample will make a popping noise and stick to the bottom of the crucible if overheated. Record anything that is observed during heating. Note: The color will change as water is removed from the sample. When the sample has turned brown, gently heat the crucible for two more minutes.
Once heating is completed, turn off the equipment and allow the sample to cool.
Turn off the Bunsen burner.
Use a pair of crucible tongs to place the crucible on a wire mesh screen on the bench.
With the tongs, move the lid so that it covers the crucible bottom completely. Allow the sample to cool for about ten minutes.
Remove the crucible cover and carefully inspect the sample. If any of the sample has maintained its initial appearance, reheat the sample until all of it has reacted.
Measure and record the mass of the cool crucible, lid, and dry (anhydrous) copper chloride sample. Record this mass to within 0.001 g.
After we allowed the sample to cool we then measured it and it had a mass of 32.222 g
Generate a solution of the copper chloride.
Transfer the brown solid to a clean and empty 50 mL beaker. Rinse out the crucible with two 8 mL aliquots (measured portions of a liquid) of deionized water and pour the water into the 50 mL beaker.
Gently swirl the beaker or stir the solution with a glass stir rod to completely dissolve the solid. Record any observations, particularly color change.
React the copper chloride solution to generate elemental copper.
Obtain a piece of aluminum wire. If the wire is dull, sand it with the sandpaper until shiny.
Coil the wire loosely around your index and middle fingers. Fewer coils are better.
Place the wire in the beaker of copper chloride solution so that it is completely immersed. It may need to be pushed down with a stir rod. Make sure the reaction goes to completion before continuing.
13. Complete the reaction.
Add 5 drops of 6 M HCl solution to dissolve any aluminum salts in the mixture, leaving a clear solution.
Use a glass stir rod to scrape off the copper from the aluminum wire into the beaker. Remove the aluminum wire from the solution and rinse it with deionized water or 1-2 drops of HCl to remove any additional copper.
Once the aluminum wire is rinsed, place the wire aside on a Kimwipe.
14. Collect and wash the copper produced in the reaction.
Set up a Büchner funnel for vacuum filtration.
Isolate the copper with the filter and rinse it with some deionized water.
Break up any large pieces of copper and rinse it twice with small amounts of deionized water.
Turn off the suction on the vacuum filtration apparatus.
15. Dry the copper sample and take mass measurements.
Measure and record the mass of a clean, dry watch glass. Record this mass to within 0.001 g.
. mass of dry watch glass 39.025 grams
Remove the filter from the Büchner funnel and transfer the copper to the watch glass. Try to disperse the copper evenly on the filter paper.
Dry the watch glass with copper in an oven for 10-15 minutes.
Remove the watch glass using crucible tongs and let the watch glass cool.
When it is cool enough to touch, measure the mass of the watch glass and copper. Record this mass to within 0.001 g.
16. Repeat drying in the oven and weighing the copper until the difference between the last
two mass measurements are within 0.005 g.
39.278 grams and second time was 39.274
Data Analysis: 1. From the mass of copper measured, determine the moles of Cu. 2. Determine the mass of chlorine in the original sample as the difference in mass between the anhydrous sample (after drying in the crucible) and the mass of copper. From the mass of chlorine, determine the moles of Cl. 3. Determine the experimental molar ratio of Cu:C 4. In Step 12, describe the components involved in the reaction. What evidence is there for a chemical reaction? Describe where the reaction is occurring on the molecular level. 5. a. Without attempting to measure the mass of the aluminum, consider the reaction that occurs in step 12, what would an increase in the aluminum mass indicate? b. What would a decrease in the aluminum mass indicate?Explanation / Answer
Mass of Cu = mass of sample + crucible - mass of crucible = 1.047 gm
1. moles of Cu = 1.047/63.5g/mol = 0.0165 moles
Mass of Cl = 32.4-32.222 = 0.178 g
2. moles of Chlorin =0.178g/35.5 g/mol =0.005 moles
3. Experimental mol ratio = Cu : Cl = 3:1
4. The color change of the solution indicates a chemical reaction.
CuCl3^- + Al (s) ----> AlCl3 + Cu (s)
grey solution is due to AlCl3 and solid Cu is at the bottom of the beaker
5. Increase in mass = formation of a Al compound
decrease in mass = Al has reacted.
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