A student dehydrated 12 grams of 2-methylcyclohexene with 85% H3PO4. What are the theoretical and percent yields?
To determine the theoretical and percent yields, we need to understand the stoichiometry of the reaction and the concept of yield.
The reaction you mentioned is the dehydration of 2-methylcyclohexanol using H3PO4 as a catalyst:
2-methylcyclohexanol (C8H16O) --> 2-methylcyclohexene (C7H14) + H2O
Before proceeding, we need to calculate the molar mass of 2-methylcyclohexene (C7H14):
- The molar mass of carbon (C) is 12.01 g/mol.
- The molar mass of hydrogen (H) is 1.01 g/mol.
- Therefore, the molar mass of 2-methylcyclohexene is (7 × 12.01) + (14 × 1.01) = 98.21 g/mol.
Now, let's calculate the theoretical yield:
Step 1: Convert the given mass of 2-methylcyclohexene to moles.
Mass of 2-methylcyclohexene = 12 grams
Molar mass of 2-methylcyclohexene = 98.21 g/mol
Using the formula: Moles = Mass / Molar mass
Moles of 2-methylcyclohexene = 12 g / 98.21 g/mol = 0.122 moles
Step 2: Calculate the moles of 2-methylcyclohexanol using the stoichiometry of the reaction.
According to the reaction equation, the ratio of 2-methylcyclohexanol to 2-methylcyclohexene is 1:1.
Therefore, the moles of 2-methylcyclohexanol = Moles of 2-methylcyclohexene = 0.122 moles.
Step 3: Convert the moles of 2-methylcyclohexanol to grams.
Molar mass of 2-methylcyclohexanol (C8H16O) = (8 × 12.01) + (16 × 1.01) = 116.22 g/mol
Mass of 2-methylcyclohexanol = Moles × Molar mass
Mass of 2-methylcyclohexanol = 0.122 moles × 116.22 g/mol = 14.19 grams
Therefore, the theoretical yield of 2-methylcyclohexene is 14.19 grams.
Now, let's calculate the percent yield:
Percent yield = (Actual yield / Theoretical yield) × 100
In this case, the actual yield is not provided. It is the amount of 2-methylcyclohexene obtained after the reaction. To calculate the percent yield, you need to measure the actual yield experimentally and substitute it into the formula.
So, without the actual yield value, we cannot calculate the percent yield.