I am trying to answer my questions for thermal decomposition of malachite lab. I have moles of malachite in 1g= 0.0045
moles of Cuo produced= 0.0009
ratio of moles of Cuo produced per moles of malachite decomposed=0.0045/0.0009=5.1
the balanced euation = CuCo3*Cu9OH)2 -----> 2Cuo+Co2+H2O
I am stuck on the next questions:
4.) Predict the mas of Cuo expected to result fron the decomposition of the malachite, based on the balanced equation
5.) Compare the mass obtained from the mass predicted, and discuss reasons for any discrepancy
6.) Suggest a way to demonstrated that Co2 is a product of the reaction
You really need to watch the caps and typing. Co and CO are NOT the same thing
I am stuck on the next questions:
4.) Predict the mas of Cuo expected to result fron the decomposition of the malachite, based on the balanced equation.
You have the moles CuO and that is correct. grams CuO = moles CuO x molar mass CuO.
5.) Compare the mass obtained from the mass predicted, and discuss reasons for any discrepancy
You will need to follow up on this. The answer depends upon how much CuO was obtained in the experiment
6.) Suggest a way to demonstrated that Co2 is a product of the reaction
It's CO2 and not Co2. CO2 is carbon dioxide. One way to test for CO2 is to allow the gas to come in contact with a film of Ca(OH)2 solution. This is usually done by dipping a wire in which the end has been bent into a circle. The inside of the wire circle then holds a small film of the solution. It turns white upon the addition of CO2. SO2 and SO3 do the same thing; however, they have an unpleasant odor whereas CO2 is odorless.
To answer the next set of questions related to the thermal decomposition of malachite, you can follow these steps:
4.) Predict the mass of CuO expected to result from the decomposition of malachite, based on the balanced equation:
In the balanced equation, you can see that 1 mole of malachite (CuCO3·Cu(OH)2) decomposes to form 2 moles of CuO. Since you have already determined the number of moles of CuO produced to be 0.0009, you can use this information to calculate the expected mass of CuO.
First, calculate the molar mass of CuO, which is 63.55 g/mol (copper's atomic mass = 63.55 g/mol; oxygen's atomic mass = 16.00 g/mol).
Next, use the formula: mass = moles × molar mass. Substituting the values:
mass of CuO = 0.0009 moles × 63.55 g/mol = (calculate the value)
5.) Compare the mass obtained from the mass predicted and discuss reasons for any discrepancy:
After calculating the mass of CuO from the previous step, compare it with the actual mass obtained from the lab experiment. If there is a discrepancy, it could be due to various factors such as incomplete reactions, impurities in the malachite sample, experimental errors, or loss of product during the lab procedure.
Discussing potential reasons for the discrepancy will require analyzing the specific experimental conditions, techniques used, and potential sources of error. It could include factors like equipment limitations, human error in measurements, incomplete decomposition, or the presence of other compounds alongside malachite.
6.) Suggest a way to demonstrate that CO2 is a product of the reaction:
To prove that CO2 is a product of the thermal decomposition of malachite, you can perform a gas evolution test. Here's one way to demonstrate it:
a) Take a test tube and add a small amount of the malachite sample.
b) Heat the malachite sample using a Bunsen burner or a suitable heat source.
c) Attach a gas collection apparatus, such as an inverted test tube or gas syringe, to the test tube to collect any gases evolved during the reaction.
d) Observe and collect any gas bubbles released during the heating process.
e) To confirm that the gas collected is CO2, pass it through limewater (calcium hydroxide solution). If the gas being bubbled through limewater turns it milky white/cloudy, it confirms the presence of CO2.
Performing this procedure should demonstrate the evolution of CO2 gas as a product of the thermal decomposition of malachite.
4.) To predict the mass of CuO expected to result from the decomposition of malachite, you can use the ratio of moles of CuO produced per mole of malachite decomposed (which you have already calculated in step 3). The molar mass of CuO is approximately 79.55 g/mol.
Given that the ratio of moles of CuO produced per mole of malachite decomposed is 5.1, and you have 0.0045 moles of malachite, you can calculate the moles of CuO produced:
moles of CuO = (5.1)(0.0045) = 0.02295 mol
To convert this to mass, you can use the molar mass of CuO:
mass of CuO = moles of CuO * molar mass of CuO = 0.02295 mol * 79.55 g/mol
Therefore, the mass of CuO expected to result from the decomposition of malachite is approximately 1.825 grams.
5.) After conducting the experiment, compare the mass obtained from the mass predicted in step 4. If there is a discrepancy, it could be due to various reasons. Possible reasons for the discrepancy could include:
- Incomplete decomposition of malachite: If the reaction did not go to completion, you may not have obtained the full expected amount of CuO.
- Loss of product during handling: Some of the CuO may have been lost during transferring or handling the product.
- Contamination: There may have been impurities mixed with the malachite or the CuO product, which could affect the mass obtained.
6.) To demonstrate that CO2 is a product of the reaction, you can perform a simple test. One way is to bubble the gas evolved during the reaction through lime water (aqueous calcium hydroxide, Ca(OH)2) solution.
When carbon dioxide (CO2) reacts with calcium hydroxide, it forms calcium carbonate, which is insoluble and appears as a white precipitate:
CO2 + Ca(OH)2 → CaCO3 + H2O
If you observe the formation of a white precipitate in the lime water, it indicates the presence of CO2, confirming that CO2 is a product of the reaction.