Acetic acid (CH3COOH) reacts with isopentyl alcohol (C5H12O) to yield the ester isopentyl acetate which has the odour of bananas. If the yield from the reaction is 45%, how many grams of isopentyl acetate are formed when 3.90 g of acetic acid and 6.28 grams of isopentyl alcohol are reacted?
CH3COOH + C5H12O → C7H14O2 + H2O
I was wondering do i have to do anything with the 45%?
Yes. This is a limiting reagent problem and we know that because amounts for BOTH reactants are given. Determine the limiting reagent. work out the theoretical yield (the amount of product you SHOULD obtain), then multiply that by 0.45 for the amount actually obtained.
I found the limiting reactant. What numbers do i use to calculate the theoretical yield?
I use one of the reagents (ignore the second) and solve for moles of the product. Then I use the second reagent (ignore the first) and solve for moles of the product. Of course this gives you two different values for the product and both can't be correct; the correct one in limiting regent problems is ALWAYS the smaller one. However, since you've already determined the limiting reagent, use that reagent and the number of grams, convert to moles, then convert to moles of the product. That will be the theoretical yield, in moles. Convert moles to grams, then multiply by 0.45. That will give you the actual yield.
how do i convert the reagent and the number of grams into moles?
Yes, you will need to take the yield into account when calculating the amount of isopentyl acetate formed. The yield of 45% means that only 45% of the theoretical maximum amount of isopentyl acetate will be obtained in the reaction.
To calculate the amount of isopentyl acetate formed, you will follow these steps:
1. Calculate the moles of acetic acid (CH3COOH) and isopentyl alcohol (C5H12O) using their molar masses.
Moles of acetic acid = mass of acetic acid / molar mass of acetic acid
Moles of isopentyl alcohol = mass of isopentyl alcohol / molar mass of isopentyl alcohol
2. Identify the limiting reactant. The limiting reactant is the one that is completely consumed in the reaction and determines the maximum amount of the product that can be formed.
3. Calculate the moles of isopentyl acetate (C7H14O2) that can be formed using the balanced equation. From the balanced equation, the stoichiometry tells us that one mole of acetic acid reacts with one mole of isopentyl alcohol to produce one mole of isopentyl acetate.
4. Calculate the theoretical yield, which is the maximum amount of isopentyl acetate that can be obtained. The theoretical yield is obtained by multiplying the moles of isopentyl acetate by its molar mass.
5. Calculate the actual yield by multiplying the theoretical yield by the percentage yield (45%).
Let's calculate it step by step:
1. Moles of acetic acid:
molar mass of acetic acid (CH3COOH) = 60.052 g/mol
Moles of acetic acid = 3.90 g / 60.052 g/mol
2. Moles of isopentyl alcohol:
molar mass of isopentyl alcohol (C5H12O) = 88.148 g/mol
Moles of isopentyl alcohol = 6.28 g / 88.148 g/mol
3. Identify the limiting reactant. To do this, compare the moles of each reactant and determine which one is present in the lesser amount. The limiting reactant is the one with the lower stoichiometric ratio to the product. In this case, we will use the stoichiometry of the balanced equation:
The balanced equation states that 1 mole of acetic acid reacts with 1 mole of isopentyl alcohol to produce 1 mole of isopentyl acetate.
Therefore, the molar ratio between acetic acid and isopentyl acetate is 1:1, whereas the molar ratio between isopentyl alcohol and isopentyl acetate is also 1:1.
Since the amount of isopentyl acetate formed is determined by the limiting reactant, we can see that the limiting reactant is the one that has fewer moles. In this case, we would need to compare the moles obtained in step 1 and step 2.
4. Calculate the moles of isopentyl acetate that can be formed based on the limiting reactant. Since the limiting reactant is determined in step 3, we will use the moles of the limiting reactant to calculate the moles of isopentyl acetate formed.
Moles of isopentyl acetate = Moles of limiting reactant
5. Calculate the theoretical yield.
Molar mass of isopentyl acetate (C7H14O2) = 130.187 g/mol
Theoretical yield = Moles of isopentyl acetate * molar mass of isopentyl acetate
6. Calculate the actual yield.
Actual yield = Theoretical yield * percentage yield (45%)
Now, you can plug in the values you obtained in each step to calculate the actual yield of isopentyl acetate formed.