Stoichiometry

1
Stoichiometry

• Chapter 9

2
The Arithmetic of Equations

• Equations are the recipes that tell chemists what
  amounts of reactants to mix and what amounts of
  products to expect.
• Stoichiometry is the calculation of quantities in
  chemical reactions.
• From a balanced equation, you can derive the
  number of particles, moles, mass and volume.
• See figure 9.4 p. 239

3
Chemical Calculations

• Mole-Mole calculations
• General Formula
• (x mol G) ((b mol W)/(a mol G)) (xb/a) mol W
• Sample problem How many moles of ammonia are
  produced when .60 mol of nitrogen reacts with
  hydrogen?
• N2(g) 3H2(g) 2NH3(g)

4
Chemical Calculations (cont)

• Mass-Mass calculations
• General steps
• The mass Z is changed to moles of Z by using the
  molar mass.
• The moles of Z are changed to moles of X by using
  the mole ratio from the balanced equation.
• The moles of X are changed to grams of X by using
  the molar mass of X.
• Sample Problem

5
Chemical Calculations (cont)

• Volume calculations
• Sample problem Tin (II) fluoride is formed in
  this reaction
• Sn(s) 2HF(g) SnF2(s) H2(g)
• How many liters of HF are needed to produce 9.40
  L H2 at STP?

6
Practice Problems

• Calculate the number of mol Ca(HCO
• Calculate the number of moles NH3 required to
  produce 2.50 mol of Cu(NH4)SO4
• CuSO4 4 NH3
  Cu(NH4)SO4