AP Chemistry TSNF

Compounds

They can be separated into elements by chemical changes

Mixtures

can be separated by physical changes and based on differences in particle size, the larger one is trapped on the filter paper

Distillation

separates mixtures based on differences in boiling points

Chromatography

separates mixtures based on differences in polarity

Paper chromatography

the component that is most similar in polarity to the mobile phase moves up the farthest.

When is mass converted?

during chemical and physical change

Reading the volume of a liquid in a container

you can estimate It by looking in between the gradual markings and this can give you one more sig fig

Least precise measurement to more precise measurement

beaker, graduated cylinder, volumetric flasks, burette. (volumetric flash has one line on it to measure specific volume)

What does density equal?

mass/volume

What doesn’t change for a pure compound?

the % composition by mass

When an electron is in a higher energy level

it is farther away from the nucleus and has less Coulumbic attraction

Moving across a row on the periodic table

The Zeef(effective nuclear charge) increases and the valence electrons are more attracted to the nucleus

When reading a PES graph

the higher the peak, the more electrons there are in that sublevel and a larger binding energy

When writing the electron configuration for a cation

remove the valence electrons first

Isotopes of an element

have the same number of protons but different numbers of neutrons

Mass spectroscopy

graphs measure atomic masses of isotops

Elements in the same group

have similar chemical and physical properties

Metals are on the

left side of the zig zag line

Non metals are on the

right side of this line of the periodic table

Cations(+) are smaller than their atoms

because you are removing valence electrons that are farther from the nucleus

anions(-) are larger than their atoms

since adding extra electrons increases electron-electron repulsion

Covalent bonds form between

two nonmetals sharing electrons

Ionic bonds are formed when

a metal transfers electrons to a nonmetal and the opposite charges attract

The greater the electronegativity difference

the more polar the bond becomes

Combustion reactions make

CO2 and H2O

Diatomic elements

H O N Cl Br I F

Empirical formula rhyme

% to mass, mass to mole, divide by small, time until whole

% yield

experimental/theoretical

% error

(experimental - theoretical)/theoretical

The amount of production for a reaction is determined by

the limiting reactants

Why are gas mixtures homogeneous?

because of the constant random motion of particles

Why are Gases compressible?

because of the large spaces between the particles

What is gas pressure caused by?

by the collisions of particles with the walls of the container. More collisions will mean more pressure

How are T and V related?

directly related (heat a balloon it will expand)

How are T and P related

directly related, heat a container and the pressure will increase

Gas constant R

0.08206

One mole of an ideal gas

22.4 L

How is gas pressure and number of moles related

directly related (double the moles and the pressure will double)

The more molar mass a gas will

move slower at a given temperature

Temperature =

Average Kinetic Energy

Gas by water displacement

Ptotal = Pdry gas + Pwater vapor

Real gases behave like

most ideal gas at high temperature and low pressure

The more polar and larger a gas is

it will deviate from ideal behavior

Small nonpolar gases are

the most ideal

Exothermic reactions are

H: it feels hot and heat is a product; temperature goes up (endothermic is the opposite)

Hrxn =

bonds broken- bonds formed

which bonds are broken and which are formed?

reactant bonds are broken and product bonds are formed

Breaking bonds

endothermic

Forming bonds

exothermic

Hrxn= Hproducts - Hreactants

multipl the coefficients as well!

exothermic reactions will result in

the bonds formed in the products are stronger/more stable than the reactant bonds

What will happen when you double a reactions

H will double

Reversing a reaction?

the sign for H changes

adding reactions?

add all the H’s

Carbon makes a total of how many bonds in compound?

4

4 domains angle

109.5

3 domains angle

120

2 domains angle

180

4 domains hybrid orbitals

sp3

3 domains hybrid orbitals

sp2

2 domains hybrid orbitals

sp

Are asymmetrical molecules nonpolar?

No because the dipoles do NOT cancel out

Are symmetrical molecules polar?

No because the dipoles cancel out

What is Lattice energy?

it is the energy to break an ionic bond in a compound.

When does Lattice energy increase?

It increases as the ion’s charge increases

When does Lattice energy decrease?

when the radii of the ions increase

What is formal charge

It involves comparing the number of valence electrons an atom has to the number of electron around it in the Lewis structure.

When to obey the octet rule

when first drawing the Lewis Dot Structure and then use formal charge if necessary

Where do the extra electrons go?

They can go on the larger central atom

When you have too few electrons?

start making some double or triple bonds

IMF’s weakest from strongest

1. London Dispersion

2. Dipole-Dipole

3. Hydrogen Bonding

4. Ion-Dipole

All molecules contain (blank) and this force gets stronger as the molecule is (blank)

• LD forces

• larger

All polar molecules contain (blank) and it gets stronger the more (blank)

• Dipole-Dipole

• polar

H-Bonds are between a NOF in one compound to a (blank) that’s already bonded to a NOF in another compound

Hydrogen

Boiling and melting point increases as (blank) increases

IMFs

Vapor Pressure and volatility (blank) as IMF’s increases

decrease

Molecular solids have low (blank) and do not (blank)

• melting/boiling points

• conduct electricity

Ionic solids have (blank) and don’t as a (blank) but do as a (blank)

• high melting/boiling point

• conduct electricity as a solid

• conduct electricity as liquid

(blanks) are covalent network solids and have very (blank)

• SiO2 and diamonds

• high boiling and melting points

Metals (blank) and their hardness (blank)

• always conduct electricity

• varies

When a molecular solid melts or boils the (blank) breaks not the (blank)

• IMFs

• covalent bonds

Interstitial alloys and Substitutional Alloys

• Interstitial can fit into gaps

• Substitutional similar sizes

Particles must (blank) at the correct orientation with the (blank) to break bonds

• Collide

• minimum activation energy

Rate constant for 1st and 2nd order

• s^-1

• M^-1s^-1

Ways to Speed up a reaction

1. Add catalyst

2. increases reaction concenetration

3. increase surface area

4. increase pressure

5. increase temperature

½ life for a 1st order process

t ½ = 0.693/k

The taller the hill the (blank) the reaction

slower

Intermediates

produced and consumed

catalysts

consumed then produced

A large keq means more (blank) at equilibirum and small keq means more (blank)

• products

• reactants

Reversing a reaction

Doubling

Adding

• 1/keq

• keq²

• Multiply

Q > Keq

shifts left to the reactant

Catalysts and inert gases Do (blank) an equilibrium

NOT SHIFT

An increase in pressure favors a shift to the side with (blank)

less moles

pH of acids are (blank) than 7 and bases are (blank) than 7

• less

• more

pH of water is only 7 when (blank)

25 C

Hydronium ion is (blank) and H is a (blank)

• H3O

• proton

if K > 1 then the (blank)

reactants are stronger

% ionization of a weak acid

H/M_a

Percent ionization increases as the (blank) decreases, adding more water will (blank)

• concentration

• increase the ionization