Chem 123 Exam 2

Avogadro's Number

6.02 x 10^23: It is a counted quantity. 1 mol=6.022 x 10^23 atoms of C.

Moles of Elements in a formula

in the compound of elements the number of atoms and number of mol of each element are the same.

Molar Mass

The mass in grams of one mole of a substance. For a compound you add the mm of each element in the compound multiplied by its subscript.

What is the mass in grams of 4.00 mol of PB?

1) 4.00 mol PB; 2) grams; 3) 4.00 g PB-> 828 grams of PB

*the coefficients of balanced equations tell you the mole-to-mole ratio; serving as free-form conversion factors, allowing us to convert moles of one species in a balanced equation into moles.

Oxidation-reduction reactions

any chemical change in which one species is oxidized (loses electrons) and another species is reduced (gains electrons); also called redox reaction

Oxidation-reduction reactions with ions

-half-reactions

-the change in the charge on an ion tells which type of reaction is occurring

Kinetic Molecular theory of gases

1) molecules are in continuous chaotic motion 2) volume of gas molecules is negligible compared to volume of the container 3) gas molecules are neither attracted nor repelled from one another 4) average kinetic energy = proportional to absolute temp and does not change if temp remains constant

Kinetic Molecular theory of gases:

1)Pressure and Volume

2)Temperature and Volume

3)Temperature and Pressure

1) inverse relationship; Boyle's Law

2) Charles's Law; direct relationship

3) direct relationship; Gay Lussac's Law

Gay Lussac's Law

-liquids have vapor pressure

-as liquid is heated, its vapor pressure increases

-liquids with low bp have high vapor pressure

Dalton's Law

- a mixture of gases, each gas exerts own pressure on container

-partial pressure

-P(total)= P(a)+P(b)+P(c)

Solution

A mixture in which one or more substances are evenly distributed in another substance

Solvent

A liquid substance capable of dissolving other substances

Solute

In a solution, the substance that dissolves in the solvent

How do solutes dissolve?

-the solute particles are next to each other at the bottom

-then they begin to stir up

-finally become dispersed

Example of a solvent

water

Strong Electrolytes

Substance that dissociates completely into its ions when added to water and conducts electricity well.

Weak Electrolytes

will dissociate partially in a reversible reaction

Solubility

A measure of how much of a substance dissolves in a given amount of another substance.

Saturated

Being the most concentrated solution possible at a given temperature.

Unsaturated

A solution that contains less than the maximum amount of dissolved solute in a concentration.

Mass percent

(mass[g] of solute/mass[g] of solution) X 100

Volume Percent

(volume of solute/ volume of solution) x 100%

Mass/volume percent

g solute/volume solution mL x 100 %

finding the solution

solute+solvent

Molarity

Concentration of a solution calculated by (mole solute)/(L solution)

Dilution

A solvent added to decrease the concentration of a solution

Colloids

A mixture that contains some particles that are intermediate in size between the small particles in a solution and the larger particles in a suspension. Particles do not settle

Suspension

A heterogeneous mixture containing a liquid in which visible particles settle.

Osmotic Pressure

Pressure that must be applied to prevent osmotic movement across a selectively permeable membrane

Osmosis

Diffusion of water through a selectively permeable membrane

Isotonic Solution

a solute concentration equal both in and out of the cell. No net movement results is an

Hypotonic

(of a solution) having a lower osmotic pressure than a comparison solution

Hypertonic

(of a solution) having a higher osmotic pressure than a comparison solution

Dialysis

Form of diffusion in which the selectively permeable nature of a membrane causes the separation of smaller solute particle from larger ones

Factors: Reaction Rate

1) Concentration

2)Temperature

3) Catalyst

Equilibrium

reactants are forming products at the same speed as products are forming reactants; no net change in the amount of reactants or products present.

Equilibrium Constant Expression

Kc= ([C]^c x [D]^d)/([A]^a x [B]^b)

Heterogeneous Equilibrium

a reaction at equilibrium in which one of the substances is in a different physical state

If Kc is a large number (Kc>10):

-more products are present at equilibrium

- equilibrium lies to the right

If Kc is a small number (Kc

-more reactants are present at equilibrium

-equilibrium lies to the left

Le Chatelier's Principle

States that if a stress is applied to a system at equilibrium, the system shifts in the direction that relieves the stress.

If H2 is added:

H2+I2

-equilibrium will shift away from HI

Endothermic

reactions have heat on the reactant side (cold: takes in heat)

Exothermic

reactants have heat on the product side (hot: releases heat)

Adding a catalyst

**has no effect on equilibrium position**

Arrhenius Theory

-an acid dissociates in solution to form H+ ions

- a base dissociates in solution to form OH-ions

Bronsted-Lowry Theory

-an acid donates (loses) H+ ions

-a base accepts (gains) OH- ions

Bronsted Base

H+ acceptor

Bronsted-Lowry & Arrhenius Acid

H+ donor

Conjugated Acid

after donating H+, the remnant of the acid

Conjugated Base

After accepting the H+

Strong acids

1) when dissolved in water, they are strong electrolytes

2) dissociates quickly

3) the H+ ions formed are accepted by the H2O

Strong Bases

1) when dissociates in water, they are strong electrolytes

) dissociates completely

3) they are usually Arrhenius Bases

Weak Acids

1)when dissolved in water, they are weak electrolytes

2) dissociates partially and are reversible

3) the H+ ions they form are accepted by H2O

Weak Acid Equilibrium

1)dissociation and subsequent reaction of a weak acid with water will reach equilibrium

2)Ka=(P1)*(P2)/(reactant acid)

3)stronger weak acids=larger Ka values and vice versa

Weak bases

1)they are usually Bronsted-Lowry Bases

2) they accept H+ ions from H2O, which acts as an acid

3) they are weak electrolytes which accepts the H+ partially and reversibly in water

Water is ________

amphoteric

acts as an acid or a base

Kw=

[H3O]*[OH-]=1.0*10^-14

pH

Acidic: 0-6

Neutral: 7

Basic: 8-14

pH of the solution (knowing H3O+):

pH=-log((H3O+)

pH of the solution (knowing pH):

(H3O+)=10^-pH

Neutralisation reaction

-the fundamental acid/base reaction

-Arrhenius acid+Arrhenius base-->water+salt

buffer solution

-Resists change in pH

-it is made by combining a weak acid and its conjugated base

Alkalosis

low blood CO2

Acidosis

high blood CO2

Organic compound

-always contain C

-H, O, S, N, P, or Group VIIA Halogens

-covalent bonds

-low boiling points

Organic bonding

-simplest organic compounds are saturated hydrocarbons

-contain only C and H atoms bonded by single bonds

Tetrahedral structure of carbons

when carbon has 4 single ones, it has 109.5 degree bond angle

Isomers

when two compounds have the same molecular formula but different arrangements of atoms

Naming

1.write alkane name of the longest chin of carbon

2. number of LCC starting from the end nearest a substituent

3.give location and name of each substituent as a prefix to the alkane name, written in abc order

4. stack identical groups

IUPAC names for the first ten Alkanes

1. METHane

2. ETHane

3. PROPane

4 BUTane

5. PENTane

6. HEXane

7. HECTane

8. OCTane

9. NONane

10. DECane

CH3-

Methyl

CH3-CH2-

Ethyl

CH3-CH-CH3

Isopropyl

F- Cl- Br- I

Fluoro, Chloro, Bromo, Iodo