UNIT 4: CHEMICAL REACTIONS DAY 3 NOTES - TYPES OF REACTIONS REVIEW- SOLUBILITY- NET IONIC EQUATIONSMs. Kondra & Mr. Olnhoff

TYPES OF REACTIONS:

Synthesis/Combination/FormationDecompositionSingle replacementDouble displacementCombustion

A. SYNTHESIS/COMBINATION/FORMATION

When 2 or more _______________ combine to produce a more ___________ substance

e.g. magnesium burns in air forming magnesium oxide

e.g. to make ammonia fertilizer (NH3), nitrogen from the air reacts with hydrogen gas

Demo: burning magnesium

B. DECOMPOSITION

the __________ of synthesis

when a more _________ substance breaks down into 2 or more _________ parts

e.g. When heated, potassium chlorate decomposes into potassium chloride and oxygen gas

e.g. When carbonic acid (hydrogen carbonate) decomposes it forms pure water and carbon dioxide bubbles appear. {By the way, this reaction can be reversed to make carbonic acid.}

Demo: potassium chlorate & gummy bear+

C. SINGLE REPLACEMENT/DISPLACEMENT

-When a ________ element replaces the _______ in an ionic compound

or

When a ____________ element replaces the _________ in an ionic compound

Use activity series on p. 136 & 216 to see if reaction will actually occur or not

e.g. If iron is added to a solution of copper sulfate, solid copper will form at the bottom of the container.

e.g. When chlorine gas is added to seawater (a solution of sodium bromide), bromine gas is produced.

 

Demo: The confused blue solution

D. DOUBLE REPLACEMENT/DISPLACEMENT

- Always involves _________ compounds

- The ________ of one compound changes places with the cation of the second

- Often a __________, ______, or _______ will be one of the products* (*we will write 'net ionic equations' for these later)

- Use solubility table on p. 459 to check if product is a precipitate

e.g. When mixed, lead (II) nitrate and sodium iodide solutions form a bright yellow precipitate. What is the name of this precipitate?

e.g. When ammonium sulfide and iron (II) sulfate solutions are mixed a precipitate of iron sulfide forms. What is the other product?

BALANCE THE FOLLOWING:(CHECK YOUR ACTIVITY SERIES CHARTS TO SEE IF THE RXN CAN HAPPEN)

1. ___Cl2 + ___NaI ___NaCl + ___I2

2. ___Ca + ___HOH ___Ca(OH)2 + ___H2

3. ___Pb + ___HCl ___PbCl2 + ___H2

4. ___Zn + ___CuCl2 ___ZnCl2 + ___Cu

5. ___Br2 + ___CaCl2 ___CuBr2 + ___Cl2

BALANCE THE FOLLOWING AND USE YOUR SOLUBILITY CHART TO DETERMINE THE STATE OF EACH COMPOUND

1. ___CaCl2 + ___Na2 SO4

2. ___AgNO3 + ___NaI

3. ___MgSO4 + ___NaOH

EXAMPLE 1Devise a procedure for separating a mixture of Ba2+ and Pb2+ by precipitating them individually.

EXAMPLE 2A solution contains a mixture of Cl- and OH-. Devise a procedure for precipitating each of these separately.

E. COMBUSTION

- Involves burning a substance in __________

- If a hydrocarbon is burnt, the products are always __________, __________ & ___________

e.g. In a barbeque, propane gas is burnt as the fuel. Write the equation.

e.g. Write the equation for the combustion of butane in a lighter.

Demo: whoosh bottle

ASSIGNMENT:Textbook: Page 464 #2-7

NET IONIC EQUATIONS

So far, the chemical equations we have looked at have been MOLECULAR EQUATIONS.

A more detailed chemical equation that shows all the particles and ions of a solution as they realistically exist is called a COMPLETE IONIC EQUATION.

The molecular equation below does not show some details of this reaction.

AgNO3(aq) + NaCl(aq) ® AgCl(s) + NaNO3(aq)

NET IONIC EQUATIONS

AgNO3(aq) + NaCl(aq) ® AgCl(s) + NaNO3(aq)

•When a salt solution is added to another salt solution, a precipitate (an insoluble compound) may form. •For example, when aqueous silver nitrate, AgNO3, is added to aqueous sodium chloride, NaCl, a white solid forms and settles out of solution. •To focus on the formation of the precipitate AgCl, it is useful to write the equation to show the ions separately.

NET IONIC EQUATIONS

AgNO3(aq) + NaCl(aq) ® AgCl(s) + NaNO3(aq)

This is how they exist in solution:

Ag+(aq) + NO3-(aq) + Na+(aq) + Cl-(aq) ® AgCl(s) + Na+(aq) +

NO3-(aq)

(Ag NO3(aq) + Na Cl(aq) ® AgCl(s) + Na NO3(aq))

•Cancel out the things that don’t change from one side of the reaction to the other. •Now we can see that only the Ag+ ion and the Cl- ion are involved in the reaction.

•The sodium and nitrate ions are called SPECTATOR IONS because they are unchanged in the reaction.

NET IONIC EQUATIONS

AgNO3(aq) + NaCl(aq) ® AgCl(s) + NaNO3(aq)

This is how they exist in solution:

Ag+(aq) + NO3-(aq) + Na+(aq) + Cl-(aq) ® AgCl(s) + Na+(aq) +

NO3-(aq)

Cancel out the spectator ions, and what is left is called the NET IONIC EQUATION.

Net Ionic Equation: Ag+(aq) + Cl-(aq) ® AgCl(s)

NET IONIC EQUATIONS

Net ionic equations can be written for any ion exchange reaction in solution.

To write net ionic equations, follow these rules:

1. Write a balanced equation showing the reactant(s) and product(s) before separation.

2. Repeat the equation with reactant(s) and product(s) separating ionic compounds where appropriate.

3. Cancel all spectator ions and rewrite the remaining net ionic equation.

NET IONIC EQUATIONS

- Used for describing double replacement reactions

- A simplified equation that shows the species directly involved in forming the precipitate, gas, or water

e.g. Write the net ionic equation for the reaction between lead nitrate and potassium iodide

1st - write the balanced formula equation:

2nd - write the TOTAL IONIC EQUATION:

3rd - cancel out the SPECTATOR IONS & write the net ionic equation

Demo with lead nitrate and potassium iodide

ASSIGNMENT:Net Ionic Worksheet Handout