1. Get Ready for your Quiz! You need When you’re done Tonight’s homework
A periodic table
Solubility rules
A calculator
A pen/pencil
When you’re done
Put your quiz in the basket
Bring me your book problems from the weekend
Tonight’s homework
Notes on section 4.3
Read through the slides (I will give them to you when you show me your homework)
If you HAVEN’T taken 1st year chemistry, reaction balancing and classification
If you have and want a refresher, it is an optional assignment
Finish your copper oxide lab report

2. AP Chemistry 2015-2016 Notes for 9/21
Warm-up
Please have your notes and practice problems out for me to check.
Write a molecular equation for the gas-evolution reaction that occurs when you mix aqueous hydrobromic acid and aqueous potassium sulfite.
Write a net ionic reaction for the reaction that occurs when you mix hydriodic acid with calcium sulfide.

3. Types of Aqueous Reactions
AP Chemistry Notes for 9/21
Types of Aqueous Reactions
Precipitation reactions (you should be an expert on these now!!)
Acid-Base reactions
Gas-Evolution Reactions
Aqueous – happening in water! These are not the only types of reactions

4. AP Chemistry 2015-2016 Notes for 9/21
Acid Base Reactions
An acid reacts with a base to form water and an ionic salt
Remember that salt is a generic term in chemistry – not just NaCl!
Acid provides H+
Base provides OH-
Example: nitric acid reacts with lithium hydroxide
HNO3 + LiOH –> H2O + LiNO3
Salt is any ionic compound
H+ + OH- = H2O (this is how neutralization works)

5. AP Chemistry 2015-2016 Notes for 9/21
Acid Base Reactions
Titration – a lab procedure where a substance of known concentration is reacted with another substance in a solution of unknown concentration in the presence of an indicator
Equivalence point – the point in the titration when the number of moles of OH- equals the number of moles of H+
Indicator – a pH dependent dye that allows the chemist to identify the equivalence point by a color change
Precipitation reactions that are then filtered for mass is called gravimetric analysis – not a titration (a mistake many of you made on your lab reports)

6. AP Chemistry 2015-2016 Notes for 9/21
Polyprotic Acids
An acid that provides more than one hydrogen ion per molecule is called polyprotic
Examples: H2SO4 (diprotic), H3PO4
Write a balanced equation for the reaction between sulfuric acid and sodium hydroxide

7. AP Chemistry 2015-2016 Notes for 9/21
Polyprotic Acids
An acid that provides more than one hydrogen ion per molecule is called polyprotic
Examples: H2SO4 (diprotic), H3PO4
Write a balanced equation for the reaction between sulfuric acid and sodium hydroxide
H2SO4 + 2NaOH –> 2H2O + Na2SO4

8. AP Chemistry 2015-2016 Notes for 9/21
H+ or H3O+?
A hydrogen ion is a single proton
In solution, H+ ions will pair up with water molecules to form H3O+
This is called the hydronium ion
In reality, it is more accurate to write your equations using the hydronium ion
In practice, it does not matter (neither Ms. Dandridge nor the College Board cares which one you use)
I use H+ because it’s 2 less characters to write and I’m kinda lazy 

9. Gas-Evolution Reactions
AP Chemistry Notes for 9/21
Gas-Evolution Reactions
Two aqueous solutions mix to form a gaseous product
Bubbles!
Common gases you should know
H2S
H2CO3 –> H2O + CO2
H2SO3 –> H2O + SO2
NH4OH –> H2O + NH3
These are the only 4 gases you need to be familiar with
Any time you see H2S, H2CO3, H2SO3, or NH4OH as a product, you should automatically think GAS EVOLUTION. For H2S, the product itself is a gas. For the other 3, there is a secondary reaction that produces a gas and another product.

10. Gas-Evolution Reactions
AP Chemistry Notes for 9/21
Gas-Evolution Reactions
Write a balanced equation (including states of matter!) for the reaction between hydrochloric acid and sodium bisulfite.

11. AP Chemistry 2015-2016 Notes for 9/21
Homework
Copper oxide lab due tomorrow!
Anyone who HASN’T taken 1st year chemistry – basic reaction type and balancing practice is required
Also available for anyone else who wants a refresher!
Tomorrow we will practice these reaction types