Stoichiometric Calculations

Stoichiometric Calculations

It only looks hard.

Stoichiometric Calculations

It only looks hard.Honest.

Stoichiometric Calculations

K + H2O → KOH + H2

If you use 0.04 mol of K,how much H2 will you produce?

Step 1: Balance the equation.

Stoichiometric Calculations

2K + 2H2O → 2KOH + H2

If you use 0.04 mol of K,how much H2 will you produce?

Step 1: Balance the equation.

Stoichiometric Calculations

2K + 2H2O → 2KOH + H2

If you use 0.04 mol of K,how much H2 will you produce?

Step 2: Ask yourself, “What do you know?”

Stoichiometric Calculations

2K + 2H2O → 2KOH + H2

If you use 0.04 mol of K,how much H2 will you produce?

Step 2: Ask yourself, “What do you know?”

Stoichiometric Calculations

2K + 2H2O → 2KOH + H2

If you use 0.04 mol of K,how much H2 will you produce?

Step 2: Ask yourself, “What do you know?”

I know how many moles of K

Stoichiometric Calculations

2K + 2H2O → 2KOH + H2

If you use 0.04 mol of K,how much H2 will you produce?

Step 3: Ask yourself, “What do you need to know?”

I know how many moles of K

Stoichiometric Calculations

2K + 2H2O → 2KOH + H2

If you use 0.04 mol of K,how much H2 will you produce?

Step 3: Ask yourself, “What do you need to know?”

I know how many moles of K

Stoichiometric Calculations

2K + 2H2O → 2KOH + H2

If you use 0.04 mol of K,how much H2 will you produce?

Step 3: Ask yourself, “What do you need to know?”

I know how many moles of KI need to know moles of H2

Stoichiometric Calculations

2K + 2H2O → 2KOH + H2

If you use 0.04 mol of K,how much H2 will you produce?

Step 4: Use the equation to find the ratio of unknown to known

Stoichiometric Calculations

2K + 2H2O → 2KOH + H2

If you use 0.04 mol of K,how much H2 will you produce?

Step 4: Use the equation to find the ratio of unknown to known

moles H2 = 1 moles K 2

Stoichiometric Calculations

2K + 2H2O → 2KOH + H2

If you use 0.04 mol of K,how much H2 will you produce?

Step 5: multiply the known number by the ratio

Stoichiometric Calculations

2K + 2H2O → 2KOH + H2

If you use 0.04 mol of K,how much H2 will you produce?

Step 5: multiply the known number by the ratio

unknownknown x known = unknown

Stoichiometric Calculations

2K + 2H2O → 2KOH + H2

If you use 0.04 mol of K,how much H2 will you produce?

Step 5: multiply the known number by the ratio

mol H2

mol K x mol K = mol H2

Stoichiometric Calculations

2K + 2H2O → 2KOH + H2

If you use 0.04 mol of K,how much H2 will you produce?

Step 5: multiply the known number by the ratio

1 mol H2

0.04 mol K x 2 mol K =0.02 mol H2

Stoichiometric Calculations

2K + 2H2O → 2KOH + H2

If you use 0.04 mol of K,how much H2 will you produce?

Step 6: the answer should have the same number of significant digits

1 mol H2

0.04 mol K x 2 mol K =0.02 mol H2

Stoichiometric Calculations

2K + 2H2O → 2KOH + H2

If you use 0.04 mol of K,how much H2 will you produce?

Step 6: the answer should have the same number of significant digits

1 mol H2

0.04 mol K x 2 mol K =0.02 mol H2

In-class work:a. Solve practice problems 9 & 10

on page 359.b. Choose a chemical equation from

chapter 10. Don’t use one that has all the coefficients = 1.

c. Write it as a problem similar to problem 9 or 10.

d. Trade with someone. You solve theirs and they solve yours.