Question

Liquid hexane CH3CH24CH3 reacts with gaseous oxygen gas O2 to produce gaseous carbon dioxide CO2 and gaseous water H2O If 0.579g of water is produced from the reaction of 0.86g of hexane and 4.7g of oxygen gas, calculate the percent yield of water. Be sure your answer has the correct number of significant digits in it.

Answer 1

To calculate the percent yield of water, we first need to determine the theoretical yield of water, which is the maximum amount of water that can be produced based on the stoichiometry of the reaction.

The balanced chemical equation for the reaction is: 2 C6H14 + 19 O2 -> 12 CO2 + 14 H2O

From the equation, we can see that 2 moles of hexane (C6H14) produce 14 moles of water (H2O).

First, we calculate the number of moles of hexane used: Molar mass of hexane (C6H14) = (12.01 g/mol * 6) + (1.01 g/mol * 14) = 86.18 g/mol Number of moles of hexane = mass of hexane / molar mass = 0.86 g / 86.18 g/mol = 0.00999 mol (rounded to 3 decimal places)

Next, we calculate the number of moles of oxygen gas used: Molar mass of oxygen gas (O2) = 16.00 g/mol * 2 = 32.00 g/mol Number of moles of oxygen gas = mass of oxygen gas / molar mass = 4.7 g / 32.00 g/mol = 0.14688 mol (rounded to 5 decimal places)

The stoichiometry of the reaction tells us that 2 moles of hexane produce 14 moles of water. Therefore, the theoretical yield of water is: Theoretical yield of water = (0.00999 mol hexane) * (14 mol water / 2 mol hexane) = 0.06993 mol (rounded to 5 decimal places)

Now, we can calculate the percent yield of water: Percent yield = (actual yield / theoretical yield) * 100 Actual yield = 0.579 g (given)

Percent yield = (0.579 g / 0.06993 mol) * 100 = 827.8% (rounded to 3 significant digits)

The percent yield of water is 827.8%.