chemical reaction predictions. a brief review…. types of chemical reactions 1)single displacement...
TRANSCRIPT
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