Stoichiometry is the quantitative study of reactants and products in a chemical reaction.
What You Should Expect
Given : Amount of reactants
Question: how much of products can be formed.
2 A + 2B 3C
Given 20.0 grams of A and sufficient B, how many grams of C can be produced?
What do you need?
You will need to use
balancing and interpreting equations, and
conversions between grams and moles.
Note: This type of problem is often called "mass-mass."
Balance the chemical equation correctly
Using the molar mass of the given substance, convert the mass given to moles.
Construct a molar proportion (two molar ratios set equal to each other)
Using the molar mass of the unknown substance, convert the moles just calculated to mass.
A mole ratio converts moles of one compound in a balanced chemical equation into moles of another compound.
Reaction between magnesium and oxygen to form magnesium oxide. ( fireworks)
2 Mg(s) + O2(g) 2 MgO(s)
2 : 1 : 2
1) N2 + 3 H2 ---> 2 NH3
Write the mole ratios for N2 to H2 and NH3 to H2.
2) A can of butane lighter fluid contains 1.20 moles of butane (C4H10). Calculate the number of moles of carbon dioxide given off when this butane is burned.
Using the practice question 2) above:
Equation of reaction
2C4H10 + 13O2 8CO2 + 10H2O
1 : 4 [ bases]
1.2 : X [ problem]
By cross-multiplication, X = 4.8 mols of CO2 given off
Problem 1: 1.50 mol of KClO3 decomposes. How many grams of O2 will be produced? [k = 39, Cl = 35.5, O = 16]
2 KClO3 2 KCl + 3 O2