ASpirin, c9h8o4, is prepared by reating salicylic acid, c7h6o3, with acetic anhydride, c4h6o3, in the reaction.

c7h6o3 + c4h6o3---> c9h8o4 + c2h4o2

A student is told to prepare 45.0 g of aspirin. she is also told to use a 55.0 % excess of acetic anhydride and to expect to get an 85.0 % yield in the reaction. how many grams of each reactant should she use?

ther's one more question.

the combustion of liquid chloroethylene, c2h3cl , yields carbon dioxide, steam, hydrogen chloride gas.

-- if 25.0 g of chloroeothylene reacts with an excess of oxygen, how many grams of each product are formed.

Note that the aspirin reaction is 1:1:1:1.

1. You want to prepare 45.0 g aspirin but since the yield is only 85.0%, you must try to prepare 45.0/0.85 = about 53 g. I rounded here and there so you need to do it exactly.

2. Convert 53 g aspirin to mols. # mols = grams/molar mass. That is the number of mols of salicylic acid (SA) you need to start with. Convert to grams by #g = mols x molar mass.

3. You will need the same number of mols of acetic anhydride EXCEPT you want to add and additional 55.0% to start.

Check my thinking. Check my work. I'm bleery eyed. It's late and I've already started on this thing and erased it FOUR times.

Second problem.
1. Write and balance the equation. The products are CO2 and H2O.

2. Convert 25.0 g chloroethylene to mols. Same formula as above.

3. Using the coefficients in the balanced equation, convert mols chloroethylene to mols CO2. Do the same thing to convert mols chloroethylene to mols H2O.

4. Now convert mols CO2 to grams and mols H2O to grams. Remember that grams = mols x molar mass.

Check my work.

To answer the first question, we need to calculate the amount of reactants needed for the given conditions.

Let's start with the balanced equation:
C7H6O3 + C4H6O3 → C9H8O4 + C2H4O2

From the equation, we can see that for each mole of salicylic acid (C7H6O3), we need one mole of acetic anhydride (C4H6O3) to react.

1. Convert the given mass of aspirin (45.0 g) to moles:
Molar mass of aspirin (C9H8O4) = (12.01 * 9) + (1.01 * 8) + (16.00 * 4) = 180.16 g/mol
Number of moles of aspirin = mass / molar mass = 45.0 g / 180.16 g/mol = 0.2497 mol

2. Calculate the moles of acetic anhydride required:
Since it is mentioned that a 55.0% excess of acetic anhydride should be used, we need to calculate 155.0% of the moles required for the reaction.

Moles of acetic anhydride = moles of aspirin * (155.0/100) = 0.2497 mol * (155.0/100) = 0.3861 mol

3. Convert the moles of acetic anhydride to grams:
Molar mass of acetic anhydride (C4H6O3) = (12.01 * 4) + (1.01 * 6) + (16.00 * 3) = 102.09 g/mol
Mass of acetic anhydride = moles * molar mass = 0.3861 mol * 102.09 g/mol = 39.43 g

So, the student should use 39.43 grams of acetic anhydride.

For the second question, we need to calculate the amount of each product formed.

The balanced equation for the combustion of liquid chloroethylene (C2H3Cl) is:
C2H3Cl + O2 → CO2 + H2O + HCl

1. Convert the given mass of chloroethylene (C2H3Cl) to moles:
Molar mass of chloroethylene (C2H3Cl) = (12.01 * 2) + (1.01 * 3) + (35.45 * 1) = 62.50 g/mol
Number of moles of chloroethylene = mass / molar mass = 25.0 g / 62.50 g/mol = 0.400 mol

2. Calculate the moles of carbon dioxide (CO2) formed:
From the balanced equation, we can see that for each mole of chloroethylene, one mole of carbon dioxide is formed.
Moles of carbon dioxide = 0.400 mol

3. Calculate the moles of water (H2O) formed:
Again, from the balanced equation, we can see that for each mole of chloroethylene, one mole of water is formed.
Moles of water = 0.400 mol

4. Calculate the moles of hydrogen chloride gas (HCl) formed:
From the balanced equation, we can see that for each mole of chloroethylene, one mole of hydrogen chloride gas is formed.
Moles of hydrogen chloride gas = 0.400 mol

5. Convert the moles of each product to grams:
Molar mass of carbon dioxide (CO2) = (12.01 * 1) + (16.00 * 2) = 44.01 g/mol
Mass of carbon dioxide = moles * molar mass = 0.400 mol * 44.01 g/mol = 17.61 g

Molar mass of water (H2O) = (1.01 * 2) + (16.00 * 1) = 18.02 g/mol
Mass of water = moles * molar mass = 0.400 mol * 18.02 g/mol = 7.21 g

Molar mass of hydrogen chloride gas (HCl) = 1.01 + 35.45 = 36.46 g/mol
Mass of hydrogen chloride gas = moles * molar mass = 0.400 mol * 36.46 g/mol = 14.58 g

Therefore, when 25.0 g of chloroethylene reacts with an excess of oxygen, 17.61 grams of carbon dioxide, 7.21 grams of water, and 14.58 grams of hydrogen chloride gas are formed.

To determine the required amounts of reactants in the first question, we need to follow these steps:

Step 1: Calculate the molar mass of aspirin (C9H8O4):
C = 12.01 g/mol
H = 1.008 g/mol
O = 16.00 g/mol

Molar mass of C9H8O4 = (9 * 12.01) + (8 * 1.008) + (4 * 16.00) = 180.16 g/mol

Step 2: Calculate the moles of aspirin desired:
Given mass of aspirin = 45.0 g
Moles of aspirin = mass / molar mass = 45.0 g / 180.16 g/mol

Step 3: Calculate the moles of acetic anhydride needed:
Since there is an 85% yield, the actual amount of aspirin produced will be 85% of the desired amount:
Actual moles of aspirin produced = 0.85 * (45.0 g / 180.16 g/mol)

To convert these moles of aspirin to moles of acetic anhydride, we use the balanced equation:
1 mole of aspirin is formed from 1 mole of acetic anhydride.
Therefore, moles of acetic anhydride = Actual moles of aspirin produced.

Step 4: Calculate the moles and mass of acetic anhydride:
Assuming an excess of 55.0%, the moles of acetic anhydride needed would be:
Moles of acetic anhydride needed = Actual moles of aspirin produced + (0.55 * Actual moles of aspirin produced)

To convert these moles of acetic anhydride to the mass of acetic anhydride using its molar mass:
Molar mass of C4H6O3 = (4 * 12.01) + (6 * 1.008) + (3 * 16.00) = 102.09 g/mol
Mass of acetic anhydride = Moles of acetic anhydride needed * molar mass of C4H6O3

For the second question, to determine the grams of each product, we need to follow these steps:

Step 1: Calculate the molar mass of chloroethylene (C2H3Cl):
C = 12.01 g/mol
H = 1.008 g/mol
Cl = 35.45 g/mol

Molar mass of C2H3Cl = (2 * 12.01) + (3 * 1.008) + 35.45 = 62.50 g/mol

Step 2: Calculate the moles of chloroethylene:
Given mass of chloroethylene = 25.0 g
Moles of chloroethylene = mass / molar mass = 25.0 g / 62.50 g/mol

Step 3: Determine the limiting reagent:
To determine the limiting reagent, we compare the moles of chloroethylene with the mole ratio in the balanced equation. The balanced equation is not provided in the question, so please provide the correct balanced equation.

Once we have the balanced equation, we can proceed to determine the moles and grams of each product.