Answers to Stoichiometry Worksheet

For those of you that missed class on Friday, here are the questions from the worksheet to help you study for the test on Monday.

In order to not reveal all of an answer at once and spoil the fun, I have changed the font color to be nearly invisible.  Just highlight the desired line to make the answers appear.

1.) How many moles of water can be formed from3 moles of hydrogen reacting with an excess of oxygen?
Equation 1: 2H2 + O2 --> 2H2O
Answer 1: 3 moles

2.) How many moles of sodium chloride can be formed from 71 grams of chlorine reacting with an excess of sodium fluoride?
Equation 2: Cl2 + 2NaF --> 2NaCl + F2
Answer 2: 2 moles

3.) How many grams of hydrochloric acid are needed to neutralize 50 mL of .2 M sodium hydroxide?
Hint: M means Molar, which means mol/liter - so there are .2 mols of NaOH /liter
Hint: multiply concentration times volume to get moles (L x mol/L = mol)
Equation 3: HCl + NaOH --> NaCl + H2O
Answer 3: .365 g HCl

4.) How many pounds of CO2 are formed when you burn a gallon of octane (C8H18)?  Octane has a density of .7 kg/L; 1 gal = 3.8 L; 1 kg = 2.2 pounds
Hint: Multiply volume times density to get mass, which you can convert to moles
Equation 4: 2C8H18 + 25O2 --> 18H2O + 16CO2
Answer 4: 17.5 pounds


Correction on 5: I accidentally put sodium bicarbonate, but I meant sodium carbonate.  Sorry.
5.)How many liters of carbon dioxide are formed at STP by the decomposition of 42 g of sodium carbonate?
Hint: STP is standard temp and pressure
Hint: V = nRT/P
Equation 5: Na2CO3 --> Na2O + CO2
Answer 5: 11.2 liters