The question is with a lab that I have already done. Here are my numbers
moles of malachite in 1g 221.12
moles of CuO produced 141.57
ratio of moles of CuO produced per moles of malachite decomposed 79.55
Use the mole ratio of CuO produced per mole of malachite to write a balanced equation for the malachite decomposition reaction. Assume that CO2 is also a product of the decomposition.
Predict the mass of CuO expected to result from the decomposition of the malachite, based on the balanced equation.
Compare the mass obtained from the mass predicted, and discuss reasons for any discrepancy.
Suggest a way to demonstrate that CO2 is a product of the reaction.
To write a balanced equation for the malachite decomposition reaction, we can use the given mole ratio of CuO produced per mole of malachite. The ratio is 79.55, which means that for every 1 mole of malachite decomposed, 79.55 moles of CuO are produced. We also know that CO2 is a product of the decomposition.
The balanced equation for the reaction can be written as:
1 mol of malachite → 79.55 mol of CuO + x mol of CO2
To predict the mass of CuO expected from the decomposition of malachite, you need to convert the moles of CuO produced (141.57) to grams using its molar mass. The molar mass of CuO is 79.55 g/mol.
Mass of CuO = moles of CuO produced × molar mass of CuO
Mass of CuO = 141.57 mol × 79.55 g/mol ≈ 11270.3335 g ≈ 11270.3 g
Therefore, based on the balanced equation, the mass of CuO expected to result from the decomposition of malachite is approximately 11270.3 grams.
To compare the mass obtained from the mass predicted, you need to compare the actual mass obtained in the lab experiment with the predicted mass. If there is a discrepancy, there could be several reasons, including experimental errors, incomplete reactions, or impurities in the malachite sample.
To demonstrate that CO2 is a product of the reaction, one way is to perform a gas test. Collect the gas produced during the decomposition reaction and pass it through a solution of calcium hydroxide (lime water). CO2 will react with calcium hydroxide to form a white precipitate of calcium carbonate. The formation of the white precipitate will confirm the presence of CO2 as a product of the reaction.
To write a balanced equation for the malachite decomposition reaction using the given ratio of moles, follow these steps:
Step 1: Write out the unbalanced equation using the reactants (malachite) and the products (CuO and CO2):
Malachite (CuCO3) → CuO + CO2
Step 2: Determine the stoichiometric coefficients for each compound in the balanced equation by using the mole ratio:
From the given ratio of moles (79.55), we can see that for every 79.55 moles of malachite decomposed, 79.55 moles of CuO are produced. Therefore, the ratio between malachite and CuO is 1:1.
So, the balanced equation for the malachite decomposition reaction is:
CuCO3 → CuO + CO2
To predict the mass of CuO expected from the malachite decomposition, use the stoichiometry of the balanced equation. The molar mass of CuO is 79.55 g/mol, which means that for every 1 mole of CuO produced, the mass is 79.55 grams.
Therefore, the mass of CuO obtained can be calculated by multiplying the moles of CuO produced (141.57 moles) by the molar mass of CuO (79.55 g/mol):
Mass of CuO obtained = 141.57 moles × 79.55 g/mol = 11,269.2 grams (rounded to four decimal places)
To compare the mass obtained from the prediction and discuss any discrepancies, simply subtract the predicted mass (11,269.2 grams) from the actual mass obtained in the lab. Any difference can be attributed to factors like experimental errors, impurities, incomplete reactions, or loss of product during the process.
To demonstrate that CO2 is a product of the reaction, you can perform a gas evolution test. Here's a suggested step-by-step demonstration:
1. Take a small sample of malachite and place it in a test tube.
2. Add a few milliliters of hydrochloric acid (HCl) to the test tube containing malachite.
3. Observe the reaction:
- If CO2 is produced, you will see effervescence, causing bubbles or fizzing in the test tube.
- If CO2 is not produced, there will be no visible change in the test tube.
4. To confirm the presence of CO2, perform a gas test:
- Insert a lit splint or a burning matchstick into the mouth of the test tube.
- If the flame extinguishes when inserted into the test tube, it indicates the presence of CO2.
Remember to handle chemicals and perform experiments safely, following proper laboratory procedures.