Need Help.............

Question

Consider the following unbalanced equation: If 2.45 g of ethanol reacts with 10.7 g of oxygen, how many moles of water are produced?

a. 0.334 mol

b. 0.160 mol

c. 0.0532 mol

d. 0.0177 mol

e. 0.669 mol

Answer 1

Hello, Anjela,

I'm not sure which part of this question is most difficult. Please add some perspective when you ask the quesion. If you've come up with a balanced equation, or done any of the mole conversions, please let us know.

I'll briefly cover the steps in the problem, but let me know if you have a question.

We need a balanced equation to start. Here's what I think might work:

C2H5OH + 3O2 = 2CO2 + 3H2O

Please check it to see if it balanced correctly. Assuming it is, we can see that we get three moles of water produced from 1 mole of ethanola nd 3 moles of oxygen. We are given mases for these two starting materials, but we need then in moles so that we can 1) determine if one is a limiting reagent, and 2) predict how mny moles of water will be produced.

Ethanol: (2.45g/46.02g/mole) = 0.05324 moles C2H5OH

Oxygen = (10.7 grams/32g/mole) = 0.334 moles O2

The balanced equation says we need 3 moles of oxygen for every 1 mole of ethanol. If we start with 0.05324 moles of ethanol, it would require 3*(0.0534) moles of O2. That's 0.159 moles, so we have more than enough O2, making C2H5OH the limiting reagent..

We'll assume all 0.05324 moles of ethanol react. The balanced equation predicts we'll make 3 moles of water for every 1 mole of C₂H₅OH. a 1:1 molar ratio. Since we consumed 0.05324 moles of C₂H₅OH, we should produce 3 times that amount of H₂O. That would result in 0.160 moles of H₂O. That's 2.87 grams, for those who are wondering.

Bob