Or

How I Learned to Stop Worrying and Love the Math… Again

Part II: Two Step Problems

Molar Conversions

Mole & particles conversion

1 mole of atoms = 6.02 x 1023 atoms

1 mole of molecules =

6.02 x 1023 molecules

Does it matter what the material is when you convert from moles to particles?

1 mole of Al= 26.981 g

1 mole MgSO4 = 120.37 g

Why is the mass of a mole different for each substance?

What is a molar mass?

Back on track: Working in MOLES

Mole & mass conversion

Mass to particle conversion

If you have 2.3 g of aluminum how many atoms of aluminum do you have?

If you have 1.5 x 1024 formula units of Magnesium sulfate, how many grams of Magnesium sulfate do you have?

Some sample 2-step problems

Particle to mass conversion

Mass

MOLES

X molar massX 6.02 * 1023

÷ 6.02 * 1023 ÷ molar mass

Particles

Sucrose has a molecular formula of C12H22O11. If you have 1 tablespoon (14.54 g)of Sucrose, how many molecules of sucrose do you have?

Try these on your own…If you have one million molecules of oxygen gas, how many grams of oxygen do you have?

If you have 75 g of ammonia how many molecules of ammonia do you have?

NH3 molar mass = 17 g/mol

Have 4.4 moles of NH3

Answer: 2.7 x 1024 molecules

O2 molar mass = 32 g/mol

1.7 x 10-18 moles

Answer:5 x 10-17 g

Try these on your own…If you have one million molecules of oxygen gas, how many grams of oxygen do you have?

If you have 75 g of ammonia how many molecules of ammonia do you have?