Rules and Laws
what does the law of conservation of mass state?
Matter can never be created or destroyed
2 KClO3 -->2 KCl + 3O2
How many moles of O2 will be formed from 1.65 moles of KClO3?
2.48 Mol O2
4 Fe + 3 O2 --> 2 Fe2O3
How many moles of Fe2O3 are produced when 0.275 moles of Fe are reacted?
0.138 moles Fe2O3
how do you identify the limiting reactant?
the reactant you run out of first
If the mass of my reactants weigh 217 grams, how much should the mass of my products weigh and why?
217 grams b/c law of conservation of mass
What is the setup for all grams to grams problems
molar mass to mole ratio to molar mass
C2H6O + 3O2 --> 2 CO2 + 3H2O
What is the mole ratio of H2O/C2H6O?
3:1
C2H6O + 3O2 --> 2 CO2 + 3H2O
How many grams of CO2 will be produced from 17 moles of O2?
498.67 grams of CO2
how do you identify the excess reactants?
the reactants that are left over
C2H6O + 3O2 --> 2 CO2 + 3H2O
determine the mole ratio of CO2 /O2
2:3
when solving a mole to mole problem you should always use what conversion factor?
mole ratio
C2H6O + 3O2 --> 2 CO2 + 3H2O
How many grams of O2 is needed to produce 126 grams of H2O?
223.75 grams of O2
2 H2O --> 2 H2 + O2
How many grams of H2O are needed to create 18 moles of H2?
324.36 grams of H2O
What is a realistic example of error in a lab
Spills, incorrect measuring, incorrect weight ect.
Why are theoretical yield and actual yield often not the same number?
theoretical yield does not take into account human error
If your given is in moles, what should your first conversion unit always be?
mole ratio
4 Fe + 3 O2 -->2 Fe2O3
How many grams of O2 are needed to react with 125 grams of Fe?
53.7 grams O2
4 Fe + 3 O2 -->2 Fe2O3
How many grams of Fe2O3 are produced when 42.7 grams of Fe is reacted?
61 grams Fe2O3
How are theoretical yield and actual yield different?
Theoretical yield is what is calculated, actual yield is what is produced and measured within a lab experiment.
How do you determine the difference between 1, 2, and 3 step problems?
mole to mole = 1 step
grams to grams = 2 step
mole to grams or grams to mole = 3 step
How do you determine which conversion unit to use first in a 2 step problem?
if you are given grams use molar mass. if you are given moles use mole ratio
2 C4H10 + 13 O2 --> 8 CO2 + 10 H2O
How many grams of CO2 are produced from the combustion of 100 grams of C4H10?
303 grams CO2
2 C4H10 + 13 O2 --> 8 CO2 + 10 H2O
How many grams of H2O are produced when 5.38g of O2 is reacted?
2.33 grams H2O
What does it mean to calculate percent yield?
Tells you what percent of a substance you were able to make from the theoretical yield
How does the law of conservation of mass relate to the theoretical yield of a chemical equation?