Single Replacement Reactions

• 1.) There are 5 major types of chemical reactions– A. Combustion: burns, explodes– B. Synthesis: to make something new– C. Decomposition: break down– D. Double Replacement: 2 elements change– E. Single Replacement: 1 element changes

Single Replacement Reactions

2.) In a single replacement reaction, 1 element replaces another element in a compound.

Replacement Reactions

3.) Not all metals can be replaced, we use the reactivity series of metals list to predict changes.

4.) The higher an element is on the list, the more likely it is to replace another element.

Replacement Reactions

Single Replacement Reactions

Example 1 : Zn + Ag(NO3) Zn (No3) + Ag

- Zinc is higher on the list than Silver, therefore it can switch places.

Single Replacement Reactions

Example 2 : Au + Ni(SO4) No reaction

- Gold is NOT higher on the list than Nickel, therefore it cannot switch places.

Single Replacement Reactions

Example 3: Zn + NiCl2 ZnCl2 + Ni

Why was Zn able to switch places with Ni?

Single Replacement Reactions

Example 4: Fe + MgCl2 No reaction

Why did the reaction not occur?

Notes. Advanced Stoichiometry with Moles

Advanced Stoichiometry with Moles

Stoichiometry looks at the relationship between the coefficients in a chemical reaction.

Stoichiometry uses dimensional analysis and balancing equations to solve a problem.

– In these multi-step t-chart problems we will use what is called a “mole ratio” in the middle of the problem.

Advanced Stoichiometry with Moles

Now that we know to convert between moles, atoms, atoms to moles, molecules to moles, moles to grams and grams to moles it’s time to put our knowledge to work and apply it to some advance chemistry problems involving Stoichiometry and dimensional analysis.

Advanced Stoichiometry and Moles

• Example One:The reaction between nitrogen monoxide

(NO) and oxygen to form nitrogen dioxide (NO2) is a key step in photochemical smog formation.

Question: How many moles of NO2 are formed by the complete reaction of 0.254 moles of O2?

Advanced Stoichiometry and Moles

Example 1:Question: How many moles of NO2 are formed by the complete reaction of 0.254 moles of O2?

Answer: In order to start solving these types of equations we are going to start at the beginning and determine what information we already know about this problem.

Advanced Stoichiometry and Moles

Example 1:Step One- What do we already know?

- We are starting with moles of O2

- We know that 1 mole of O2= molecules of O2

- We know that the molar mass of O2 is= grams.

- We know that according to the chemical equation shown above moles of NO are needed to react with

mole of O2 in order to form moles of NO2.

What do we want to know?- We want to find out how many moles of are

formed.

Advanced Stoichiometry and Moles

Example 1:Step Two- Set-up the Dimensional Analysis Problem using the steps we have discussed before:

Advanced Stoichiometry and Moles

Example 2: Ammonia (NH3) can be formed from the elements N2 and H2, as shown below.

N2 + 3H2 2NH3

Question: How many moles of ammonia can be made from .7 moles of H2?

Answer: In order to start solving these types of equations we are going to start at the beginning and determine what information we already know about this problem.

Advanced Stoichiometry and Moles

Example 2:Step One- What do we already know?

- We are starting with moles of H2

- We know that 1 mole of H2= molecules of H2

- We know that the molar mass of H2 is= grams.

- We know that according to the chemical equation shown above moles of N2 are needed to react with

mole of H2 in order to form moles of NH3.

What do we want to know?- We want to find out how many moles of are

formed.

Advanced Stoichiometry and Moles

Example 2:Step Two- Set-up the Dimensional Analysis Problem using the steps we have discussed before:

Advanced Stoichiometry and Moles

Example 3: The reaction between nitrogen monoxide (NO) and oxygen combine to form nitrogen dioxide (NO2) is a key step in photochemical smog formation.

2 NO + O2 2NO2

Question: How many grams of NO2 are formed by the reaction of 1.44 grams of NO with excess O2?

Answer: In order to start solving these types of equations we are going to start at the beginning and determine what information we already know about this problem.

Advanced Stoichiometry and Moles

Example 3:Step One- What do we already know?

- We are starting with moles of NO

- We know that 1 mole of NO= molecules of NO- We know that the molar mass of NO is=

grams.- We know that according to the chemical equation

shown above moles of NO are needed to react with mole of O2 in order to form moles of

NO2.

What do we want to know?- We want to find out how many of NO2 are

formed.

Advanced Stoichiometry and Moles

Example 3:Step Two- Set-up the Dimensional Analysis Problem using the steps we have discussed before:

Advanced Stoichiometry and Moles

Example 4: Use the reaction below to answer the following question.

CH4 + 2 O2 CO2 + H2O

Question: How many grams of H2O are formed by the reaction of 5.78 grams of CH4 with excess O2?

Answer: In order to start solving these types of equations we are going to start at the beginning and determine what information we already know about this problem.

Advanced Stoichiometry and Moles

Example 3:Step One- What do we already know?

- We are starting with grams of CH4

- We know that 1 mole of CH4= molecules of CH4

- We know that the molar mass of CH4 is= grams.

- We know that according to the chemical equation shown above moles of CH4 are needed to react with

mole of O2 in order to form moles of H2O.

What do we want to know?- We want to find out how many of H2O are

formed.

Advanced Stoichiometry and Moles

Example 4:Step Two- Set-up the Dimensional Analysis Problem using the steps we have discussed before:

Stoichiometry

Ex. 5 How many grams of H2O are produced if you begin with 98.4 g of O2?

H2 + O2 H2O

Stoichiometry

Ex. 6 How many grams of Cl2 are needed to make 209g of NaCl? Na + Cl2 NaCl

Stoichiometry

Ex. 7 How many grams of CO2 are produced from 318g of O2?

CO + O2 CO2

Notes. Limiting Reagent

Limiting Reagents

• What is a limiting reagent?

Limiting Reagents

• 1.) A limiting reagent/ reactant is a substance needed to start a chemical reaction that we run out of and prevents us from doing the equation again.

Limiting Reagents

Baking or cooking recipes are good examples of limiting reactants because eventually you will run out of one of the ingredients you need

Example: Let’s say you want to bake a batch of cookies. First ,you google a sugar cookie recipe and find the recipe with the following ingredients (3 eggs, ½ cup milk, 1 cup flour, 2 cups sugar). Second, you find the needed ingredients and determine how many batches you can make given the ingredient amounts below.

Limiting Reagents

Recipe Ingredients You Have

3 eggs 12 eggs

½ cup milk 2 cups milk

1 cup flour 4 cups flour

2 cups sugar 6 cups sugar

2.) Which ingredient will you run out of first?

3.) Which ingredients on hand were in excess for the recipe?

Limiting Reagents

4.) You have 100 bolts, 150 nuts and 150 washers. You assemble a nut/bolt/washer set using the following recipe or equation. 2 washers + 1 bolt + 1 nut = 1 set • How many sets can you assemble from your supplies?

• Which is the limiting component?

Limiting Reagents

• We can use this same logic used above in our hotdog, cookie and nuts/bolts/washer example and apply it to chemical reactions. When dealing with a chemical equation, the chemical of which there are fewer moles than the reaction requires is the limiting reagent. In order to solve limiting reagent problems we need to follow 3 main steps.

Limiting Reagents

Steps to Solving Limiting Reagent Problems1.) Balance the equation2.) Convert all numbers to moles.3.) Compare number of moles you have available to the number of moles you need in a balanced equation.

Limiting Reagents• Example 1: If 6 moles of H2 and 4 moles of O2

are mixed and reacted, which is the limiting reagent?

• Step 1: Balance the chemical equation H2 + O2 H2O

• Step 2: Convert all numbers to moles. • Step 3: Compare number of moles you have

available to the number of moles you need in the balanced equation.

Limiting Reagents• Example 1: If 6 moles of H2 and 4 moles of O2 are mixed and reacted, which is the

limiting reagent?

H2 + O2 H2O

What is the limiting reactant?

How many moles of water would be produced?

Limiting Reagents• Example 2: 200 g of Na react with 200g Cl2. What is the limiting

reactant?Step 1: Balance the equation

Na + Cl2 Na Cl

Step 2: Convert all numbers to moles.Step 3: Compare number of moles you have available to the number of moles you need in the balanced equation.

• What is the limiting reactant?

Limiting Reagents• Example 3: If you had 17.3 g of Hydrogen and 8.91g

of oxygen, which is the limiting reagent, and how many grams of water could you produce?

Limiting Reagents• Example 4: Solid sodium and iron (III) oxide are involved

in a reaction that is one of many reactions responsible for inflating a car airbag. If 100.0 g Na and 100.0 g Fe2O3 are used, determine:

6 Na + Fe2O3 3 Na2O + 2Fe

a.) Limiting reactantb.) Excess reactantc.) Mass of solid iron producedd.) Mass of excess reactant left over

Limiting Reagents• In order to solve this problem we will need to:a.) Start with one reactant and turn it into the other reactant (either one is fine to start with). Compare the answer with the given amount in the problem to determine if you have more of less of what is given. From this information, the limiting reactants can be determined.b.) Using information in A, determine the excess reactant.c.) Determine how many grams of the product, Iron, can be formed, starting with the limiting reactant.d.) Determine how much of your excess reactant is left over.

Limiting Reagents• Example 4: Solid sodium and iron (III) oxide are involved in a reaction that

is one of many reactions responsible for inflating a car airbag. If 100.0 g Na and 100.0 g Fe2O3 are used, determine:

6 Na + Fe2O3 3 Na2O + 2Fe