Chapter 9 moles, equations, and stoichiometry

Moles, Equations, and Stoichiometry

Moles Atoms

• How many sucrose molecules do you have if the beaker contains 3.5 moles?

Hint:How many bagels do you have in 3.5 dozen?

2.107 x 1024

1.How many molecules in 0.36 mol of water?

2.How many atoms are in 1.14 mol SO3?

Atoms Moles

• If you have 5.75 x 1024 atoms of Copper, how many moles do you have?

9.55 moles

1.How many moles is 2.8 x 1024 atoms of silicon?

2.How many moles is 3.7 x 1024 molecules of CO2?

Balanced Equation

N2 + H2 → NH3

N2 + 3H2 → 2 NH3

Balanced Equation

N2 + 3H2 → 2 NH3

• Number of atoms• Number of molecules• Number of moles

Mole ratio

• N2 + 3H2 → 2NH3

• conversion factor derived from the coefficients of a balanced equation

• N2 + 3H2 → 2NH3

• If you have 7 moles of H2 and you want to know how much NH3

–What would you do?

Chemical Reactions???Lets Start Over!

• What is a Chemical Reaction?• What is all this math really about?

Chemical Reaction

• Combustion

Magnesium Oxide

1 Mg + 1 O 1 MgO

Mg + O MgO

12Mg + 12O 12MgO

mol Mg + mol O mol MgO

Chemical Reaction

• Combustion

2mol C2H2 + 5 mol O2 4 mol CO2 + 2 mol H20

Avogadro’s Number

6.02 × 1023

• Number of atoms in 12 grams of Carbon-12

Molar Mass

The mass of 1 mole of a substance

Molar MassUsing the Periodic Table

N2 + 3H2 → 2 NH3

• mass of 1 mol of N2 =

28 g• mass of 3 mol of H2 =

6 g• mass of 2 mol of NH3 =

34 g

• If you find the mass of a sample of glucose (C6H12O6) to be 90.0 g, how many moles of glucose do you have?

• A certain laboratory procedure requires the use of 0.100 moles of magnesium. How many grams of magnesium would you mass out on the balance?

2 step problem

• What would be the mass of 3.75 x 1021 atoms of iron?• First change number of atoms to moles• Now, change number of moles to mass