Chemical Reaction Predictions

A brief review….

Types of Chemical Reactions

1) Single Displacement

2) Double Displacement

3) Decomposition

4) Synthesis

5) Combustion

Single Displacement

A +BC AC + B

One element shoves the other element out!

Ex. Ca + AlCl3 CaCl2 + Al

Double Displacement

AB + CD AC + BD

Elements switch partners !

Ex. Na3PO4 + BaCl2 Ba3(PO4)2 + NaCl

Decomposition

AB A + B

Breaking chemical compound up, going from BIG to SMALL !

Ex. Au2O3 Au + O2

Synthesis

A + B AB

Joining! Making new chemical compound !

Mg + N2 Mg3N2

Combustion

HYDROCARBON (compound made up of just Cs and Hs) + O2 CO2 + H2O

Chemical reactions involve a compound burning.

Ex. C2H6 + O2 CO2 + H2O

Practice

1) Zinc metal combines with hydrochloric acid (HCl).

2) Sodium sulfide combines with magnesium oxide.

3) Sodium metal combines with sulfur.

4) Calcium oxide breaks down.

5) C4H8 burns

6) Gandalf combines aluminum metal with sodium hydroxide in solution. What does he produce?]

Aqueous Solutions

Compounds dissolved into water.

Can contain molecules or ions in a solution.

How do you distinguish between ion or molecule?

DISSOCIATION !!

The ability of a compound to breakdown in a solution into individual ions

Ionic Compounds Break down into cations and anions Electrical conductors—ions flow through

solution

Molecular Compound Compound remains intact as “molecules,” no

breakdown Generally NOT electrical conductors

Dissociation Reactions

1) NaCl

2) CaCl2

Nonelectrolyte NO dissociation of the compound into anions and

cations

Compound remains in its molecular form when dissolved in a solution

No conduction of electricity

Ex. Pure water, molecular compounds, organic compounds

Electrolytes

Compound dissolved in a solution that breaks down into cations and anions.

Dissociates into enough ions to conduct electricity.

Strong vs. weak—dependent on the amount of ions in the solution

Strong Electrolyte

LOTS of ions present in solution Light bulb burns brightly !

Complete dissociation of the compound into ions

Good electrical conductor

Ex. NaCl, all soluble ionic compounds, very few molecular compounds

Weak Electrolyte

Compound is at a crossroads part dissociates into ions—partial ionization part still exists in the molecular form

Some electrical conduction but poor

Dimly lit light bulb

Ex. Acetic acid, carboxylic acid/amines

What is the concentration ([ ]) of a

particular ion in solution?

Sometimes [ion] = [compound], but not always

An ion can have only ONE concentration in a solution May have multiple sources for one ion. What do

you do then? (add them up)

Example 1:

Hercules has obtained an aqueous solution of 0.00384 M Na2SO4 and 0.00202 M NaCl. What is the concentration (in molarity) of each ion present in the solution? Total ion concentration?

Example 2:

Oral Rehydration Therapy (ORT) is an electrolyte solution containing 3.5 g NaCl, 1.5 g KCl, 2.9 g sodium citrate (Na3C6H5O7) and 20.0 g glucose (C6H12O6) in 1 liter. What is the molarity of each ion/molecule in a solution of ORT? Hint: sodium citrate is a strong electrolyte,

glucose is a nonelectrolyte

Solubility

How much solute dissolves in a solution to produce a saturated solution

Temperature and Pressure dependent Increase with increasing temperature Increases with decreasing temperature (ex. Water

in lake) Pressure increases, solubility increases (ex. Soda

can)

Particles move back and forth from being dissolved to leaving a solution—equilibrium is reached when this movement is balanced.

A point is reached where adding more solute to a solution will prevent the solute from dissolving in the solution.

Types of Solutions 1) Saturated

Maximum amount of solute that can be dissolved in a solvent

Certain temperature and pressure2) Unsaturated

Solution with LESS solute than the maximum solute amount at a certain temperature and pressure

More solute can be added and dissolved in the solution

3) SupersaturatedContains MORE solute than the maximum

solute amount

Solubility Diagrams

Solubility Rules

How do we determine which compounds will dissolve in water or not?

Based on data, patterns have been observed and helped develop the rules we follow

Which compounds are soluble in water?

1) BaCl22) Pb (NO3)2

3) Na2S

4) BaCO3

5) PbS

Your Turn…….

NaCl

KBr

KNO3

AP Question

Snow White conducts a complete combustion of a hydrocarbon with excess oxygen. This combustion produces equimolar quantities of carbon dioxide and water. What is a possible molecular formula for the compound?

A) C2H2

B) C2H6

C) C4H8

D) C6H6