Stoichiometry Chapter 11. Skills from Previous Chapters The following skills are not the only ones,...

Stoichiometry

Chapter 11

Skills from Previous Chapters

• The following skills are not the only ones, but the main ones:Name to formulaBalancing equationsMolar conversions Conversion factorsMolar mass

New Skills to be Learned

Determine mole to mole ratiosStoichiometric calculations

Mole to moleMole to gramGram to gram

Determine limiting reactant

What is stoichiometry?

• The study of quantitative relationships between amounts of reactants used and amounts of products formed by a chemical reaction.

Mole to Mole Ratios

• First, we need an equation.

• Next we need to balance it.

Mole to Mole Ratios

• Once, the equation is balanced, identify the coefficients.

• These coefficients form the basis of the ratios.

Mole to Mole Ratios

• What is the ratio of hydrogen to nitrogen?

Problem 1

1. NaNO3 + PbO Pb(NO3)2 + Na2O

2. What is the mole ratio of PbO to Na2O?

3. What is the mole ratio of NaNO3 to Pb(NO3)2?

Problem 2

1. AgI + Fe2(CO3)3 FeI3 + Ag2CO3

2. What is the mole ratio of AgI to FeI3?

3. What is the mole ratio of Ag2CO3?

Problem 3

1. C2H4O2 + O2 CO2 + H2O

2. What is the mole ratio of C2H4O2 to O2?

3. What is the mole ratio of O2 to CO2?

Problem 4

1. ZnSO4 + Li2CO3 ZnCO3 + Li2SO4

2. What is the mole ratio of ZnSO4 to ZnCO3?

3. What is the mole ratio of Li2CO3 to ZnCO3?

Problem 5

1. V2O5 + CaS CaO + V2S5

2. What is the mole ratio of CaS to V2S5?

3. What is the mole ratio of CaO to V2S5?

Mole to Mole Problems

• Mole to mole ratios are key in determining the number of moles needed or produced of one element or compound, when given the moles of another.

Mole to Mole Problems

• First, an equation must be provided.– Either in word or skeletal form.

• If in words, you must change it into skeletal.

Mole to Mole Problems

• Second, the equation must be balanced.

Mole to Mole Problems

• Third, read the problem carefully. Identify what the problem is asking for.

• Example Problem:– In the aforementioned reaction, if 12 moles of

hydrogen is reacted, how many moles of oxygen would be needed to complete the reaction?

– What are they giving us?• 12 moles of Hydrogen

– What are they looking for?• Moles of oxygen

Mole to Mole Problems

• Once, the given and wanted are established, we set up our problem. Since this is a mole to mole problem, only ONE conversion factor is needed.

Mole to Mole Problems

• In order to fill in the numbers, we must find the mole ratio of hydrogen to oxygen. Then we fill in the numbers.

Mole to Mole Problems

• Lastly, we calculate the answer.

Practice Problems

• C2H4O2 + O2 CO2 + H2O

• If Bob is reacting 20 moles of oxygen, how many moles of carbon dioxide would he produce?

• If Sue produced 12.5 moles of water, how many moles of C2H4O2 were used?

Practice Problems (2)

• AgI + Fe2(CO3)3 FeI3 + Ag2CO3

• If .09 moles of Iron (III) iodide were produced, how many of silver (I) carbonate were produced?

• If 1.25 moles of iron (III) carbonate were used, how many of silver (I) iodide should have been?

Practice Problems (3)

• Al + O2 Al2O3

• If 30 moles of aluminum are used, how many of aluminum oxide should be produced?

• If .05 moles of oxygen are used, how many of aluminum oxide should be produced?

Homework

• P. 372– Practice Problems 3 and 4

• P. 392– #47 to 52

• Study for Quiz on Mole to Mole problems

Mole to Gram Problems

• Going from moles to grams in an equation is based off of the ability to implement mole to mole problems.

• Within these mole to gram problems, two conversion factors will be used.– Mole to mole ratios– Molar mass

Mole to Gram Problems

• First, an equation must be provided.– Either in word or skeletal form.

• If in words, you must change it into skeletal.

Mole to Gram Problems

• Second, the equation must be balanced.

Mole to Gram Problems

• Third, read the problem carefully. Identify what the problem is asking for.

• Example Problem:– In the aforementioned reaction, if 12 moles of

hydrogen is reacted, how many grams of oxygen would be needed to complete the reaction?

– What are they giving us?• 12 moles of Hydrogen

– What are they looking for?• Grams of oxygen

Mole to Gram Problems

• Once, the given and wanted are established, we set up our problem. Since this is a mole to gram problem, two conversion factors are needed.

Mole to Gram Problems

• In order to fill in the first conversion factor, we must find the mole ratio of hydrogen to oxygen. Then we fill in the numbers.

Mole to Gram Problems

• In order to fill in the second conversion factor, we must find the molar mass of O2.

Mole to Gram Problems

• Once, the given and wanted are established, we set up our problem. Since this is a mole to gram problem, two conversion factors are needed.

Mole to Mole Problems

• Lastly, we calculate the answer.

Practice Problems

• C2H4O2 + O2 CO2 + H2O

• If Bob is reacting 11 moles of oxygen, how many grams of carbon dioxide would he produce?

• If Sue produced 9 moles of water, how many grams of C2H4O2 were used?

Practice Problems (2)

• AgI + Fe2(CO3)3 FeI3 + Ag2CO3

• If 9 moles of Iron (III) iodide were produced, how many grams of silver (I) carbonate were produced?

• If 1.5 moles of iron (III) carbonate were used, how many grams of silver (I) iodide should have been?

Practice Problems (3)

• Al + O2 Al2O3

• If 3 moles of aluminum are used, how many grams of aluminum oxide should be produced?

• If .5 moles of oxygen are used, how many grams of aluminum oxide should be produced?

Homework

• P. 376– Practice problems # 13, 14

• Study for quiz

Gram to Gram Problems

• Going from grams to grams in an equation is based off of the ability to implement mole to mole problems.

• Within these mole to gram problems, three conversion factors will be used.– Molar mass– Mole to mole ratios– Molar mass

Gram to Gram Problems

• First, an equation must be provided.– Either in word or skeletal form.

• If in words, you must change it into skeletal.

Gram to Gram Problems

• Second, the equation must be balanced.

Gram to Gram Problems

• Third, read the problem carefully. Identify what the problem is asking for.

• Example Problem:– In the aforementioned reaction, if 100g of

hydrogen is reacted, how many grams of oxygen would be needed to complete the reaction?

– What are they giving us?• 100g of Hydrogen

– What are they looking for?• Grams of oxygen

Gram to Gram Problems

• Once, the given and wanted are established, we set up our problem. Since this is a mole to gram problem, three conversion factors are needed.

Gram to Gram Problems

• In order to fill in the first conversion factor, we must find the molar mass of hydrogen. Then we fill in the numbers.

Gram to Gram Problems

• In order to fill in the second conversion factor, we must find the mole ratio of hydrogen to oxygen.

Gram to Gram Problems

• To find the third conversion factor we must find the molar mass of oxygen.

Mole to Mole Problems

• Lastly, we calculate the answer.

Practice Problems

• C2H4O2 + O2 CO2 + H2O

• If Bob is reacting 250 grams of oxygen, how many grams of carbon dioxide would he produce?

• If Sue produced 9 gramsof water, how many grams of C2H4O2 were used?

Practice Problems (2)

• AgI + Fe2(CO3)3 FeI3 + Ag2CO3

• If 10 grams of Iron (III) iodide were produced, how many grams of silver (I) carbonate were produced?

• If 150grams of iron (III) carbonate were used, how many grams of silver (I) iodide should have been?

Practice Problems (3)

• Al + O2 Al2O3

• If 30 grams of aluminum are used, how many grams of aluminum oxide should be produced?

• If 500grams moles of oxygen are used, how many grams of aluminum oxide should be produced?

Homework

• P. 377– Practice problems #15, 16

• Study for quiz

Limiting Reactants

Limiting Reactant

• Involves Gram to Gram conversions

Example Problem

• The reaction between solid white phosphorus (P4) and oxygen produces solid tetraphosphorus decoxide (P4O10).

• Determine the mass of P4O10 formed if 25g of P4 and 50g of oxygen are combined.

• How much excess reactant remains after the reaction stops?

First

• Write the equation, and balance it.

Second

• Do gram to gram conversions for each of the reactants.

So…

• The limiting reactant is the one that produces the least amount!

• So, oxygen is the limiting reactant and 44.38g of P4O10 are formed.

• Now, we must answer the second part of the question.

Third

• Now, we must find out how much of the excess reactant (P4) is left over. So we must determine how much we use. To do this we must back convert from the product to P4.

Fourth

• We subtract the used amount from the original amount, and find the excess.

Problems

• Handouts

Homework

• P. 394– #76 to 82

End of Chapter

• Time for review packet.