Notes for Monday, April 19, 2010

Test Wednesday, everybody! If you can't do molarity problems, molality problems, or problems on colligative properties, then start practicing. Feel free to comment with practice problems.

• A monoprotic acid is an acid that can donate only one proton.
• A polyprotic acid can donate more than one proton per molecule.
• A diprotic acid can donate to protons per molecules, and a triprotic acid can donate three protons per molecule.
• A Lewis acid is an atom, ion, or molecule that accepts one electron pair to form a covalent bon. This is the broadest of the three acid definitions. A bare proton is a Lewis acid. This is the only definition that is not based on hydrogen. A silver ion can be a Lewis acid, for instance.

Here's a table for remembering the different definitions of acid.

-	Acid	Base
Arrhenius	H, H3O producer	OH producer
Bronsted-Lowry	proton donor	proton acceptor
Lewis	electron-pair acceptor	electron-pair donor

• The species that remains after a Bronsted-Lowry acid has given up its proton is the conjugate base of that acidd.
• Bronsted-Lowry acid-base reactions involve 2 acid-base pairs, known as conjugate acid-base pairs.

And no, I don't have a clue why Blogger put a giant gap before the table.

4/16/10

Today, Dr. Bautista was not here. We watched a movie on Mars. It was very interesting and showed the time and dedication of the teams operating the rovers. Very soon we will know more about Mars.

Chemistry Notes for Thursday, 4/15

In class we discussed how Dr. B checked and graded the R constant labs. I however, do not have those notes, and leave it to you guys to fill that part in.
CLASS NOTES:
- Arrhenius Acids are molecular compounds with ionizable hydrogen atoms
-Their water solutions are known as aqueous acids
-All aqueous acids are elctrolytes
- A strong acid ionizes completely in aqueous solutions.
-Strong acids are strong electrolytes
Ex: HClO4 HCl, HNO3

-A weak acid relaes few ions in aqueous solutions
- Hydronium ions, anions, and dissolved acid molecules in aqueous solutions
Ex: HCN
-organic acids (____COOH molecules), such as acetic acid are weak acids

-Most bases are inoic compounds containing metal cations and the OH- anion
-Ammonia, NH3, is molecular
-Ammonia produces OH- ions when it reacs with water molecules
-The strength of a base depends on the extent in which it dissociates in a solution
-Strong bases --> Strong electrolytes
Amount of H3O+'s to OH-'s in types of solutions
Acidic
H3O+ > 10^-7 Moles >OH-
Nuetral
H3O+ = 10^-7 Moles = OH-
Basic
H3O+ < 10^-7 Moles< OH-

Bronsted Lowry Acids and Bases
- A Bronsted Lowry-Acid is a molecule or ion that is a proton donor
-HCl acts as a Bronsted-Lowry acid when it reacts with ammonia
-Water can act as a Bronsted-Lowry Acid
-A Bronsted-Lowry Base is a molecule or ion that Acts as a proton acceptor
-Ammonia accepts a proton from HCl, and is therefore and Bronsted-Lowry Base
- the OH- ion produced in solutions by acids is a Bronsted-Lowry Base

- In a Bronsted-Lowry Acid-Base reaction, protons are transferred from one reactant(the acid) to another (the base)

The blog by chris mathews

today we talked about acids, but not before we went over some very challenging chemistry questions. Good news of the day is that kyle "Half Caff McCaffery" (if i spelled it wrong please correct me) was moved and now gets to sit with us in the front

back to the notes

first acids are aqueous solutions that usually have a sour taste, they can change the color of an acid-base indicator, react with active metals to release H2 gases, react with bases to produce water and salts, and finally conduct electricity.

binary acid- acid that contains only two elements, one of which has to be hydrogen and the other and electronegative element.

examples are HF HCl HBr

the name starts with -hydro for the hydrogen element

then to the root of the second element comes into play

finally all of this is followed by an "ic"

ex. HF is know as hydrofluoric acid notice the suffix and prefix usage

next we have the oxyacid-is an acid that is a compound of oxygen, hydrogen, and usually a nonmetal. these names also follow a pattern

names of anion are based on the names of the acid. next if the anion ends in ate it is an "ic" ending but if the anion ends with ite its ending is "us"

now we have sulfuric acid

apparantly its one of the most commonly produced industrial chemicals in the world, but dont clean the container holding it, or it will corrode!!!

nitric acid, phosphoric acid had no definitions...

hydrochloric acid- concentrated solutions of this acid are commonly called muriatic acid

acetic acid-pure acetic acid is clear, colorless, and pungent smelling liquid that is also known as

glacial acetic acid

i do believe this is the point in class where colby maybry made the brilliant oration on the different levels of acid strength, all of which are related to disassociation.

bases

they taste bitter, change with acid base test, dilute solutions feel slippery, react with acids to produce water and salt, and conduct electricity.

this is all i got for the day. Thank you and have a wonderful evening

ps quiz tomorrow over ch 13 calculations, this should be a good way to bring those averages up guys and remember that the test will be next thursday.

-Electrolytes & Colligative Properties cont'd.

-the actual values of the colligative properties for all strong electrolytes are almost always what would be expected based on the number of particles they produce in solution

-the differences are caused by attractive forces between dissociated ions in aqueuous solution

-according to Debye & Huckel, a cluster of hydrated ions acts as a single ion rather than as individual ions, causing effective total concentration to be less

-Ions of higher charge have lower effective concentrationss than ions with smaller charge

Multiple Choice

1. Acetic acid is a weak electrolyte because it

D. ionizes only slightly in aqueuous solution

2. Which of the following solutions would contain the highest concentration of hydronium ions?

A. 0.10 M HCl

3. Which of the following is the best representation of the precipitation reaction that occurs when aqueuous solutions of sodium carbonate and calcium chloride are mixed?

C. CO3(2-) (aq) + Ca(2-) --> CaCO3(s)

4. Which of the following is not a colligative property?

A. molality

5. Solution A contains 0.1 mol of sucrose, C12H22O11, dissolved in 5oo g of water. Solution B contains 0.1 mol of sodium chloride, NaCl, in 500 g of water. Which of the following is true?

C. Solution A would freeze at a higher temperature than Solution B would.

colligative properties of solutions

colligative properties

• Properties that depend on the concentration of solute particles but not on their identity

the boliing point of a solution differ from those of the pure solvent

nonvolatile substance

• substance that has little tendency to become a gas under existing conditions

nonelectrolyte solutions of the same molality have the same conecntration of partilces.

freezing-point depression

• the freezing-point depressino of a 1 m solution of any nonelectrolyte solute in water is found by experiment to be 1.86 degrees Celsius lower than the freezing point of water.

molal freezing-point constant

• the freezing point depresino of the solvent in a 1-molal solutino of a nonvolatile, noneletrolyte solute

freezing point depression

• the difference between the freezing points of the pure solvent and a solution of a nonelectrolyte in that solvent, and it is directly proportional to the molal concentration of the solution

Ksub f is expressed as degrees Celsius/m

each solvent has its own characteristic molal freezing point constant

boiling point elevation

• the boiling point of a liquid is the temperature at which the vapor pressure of the liquid is equal to the prevailing atmospheric pressure
• a change in the vapor pressure of the liquid will cause a corresponding change in the boiling point

molal boiling point constant

• the boiling point elevation of the solvent in a 1-molal solution of a nonvolatile, nonelectrolyte solute.
• the boiling point elevation of a 1-molal solution of any nonelectrolyte solute in water has been found by experiment to be 0.51 degrees C

boiling point elevation

• the difference between the boiling points of the pure solvent and a noneletrolyte solution of that solvent, and is directly proportional to the molal concentration of the solution
• change in temperature = (constant of temperature) (m)

osmotic pressure

• the external pressure that must be applied to stop osmosis

osmosis

• the movement of solvent through a semipremeable membrane from the side of lower solute concentration to the side of higher concentration

semipermeable membrane

• membrane that allows the passage of some particles while blocking the passage of others

Weekend Blog

Strong electrolyte - compound in an aqueous solution that conduct electricity well/many ions/strong acids contain strong electrolytes

Weak electrolyte - poor conductors of electricity/ very few dissolved ions/ no ionic compounds

Colligative properties - depend on concentration of solution

Vapor-Pressure Lowering

Freezing-Point Depression

Boiling-Point Elevation

Osmotic Pressure

Nonvolatile substance- substance with little tendency to become gas

In nonvolatile substances Boiling-Point rises Freezing-Point lowers