Unit 2 “Equilibrium” (keq& ka)

in what systems does equilibriums happen

Closed systems

Is an equilibrium reversible

Yes

Electrolytes

Always ionic and conduct electricity when dissolved

What determines if electrolytes will dissolve more or less

The strength of the attraction

If there are more ions what does it mean for the attractions

They will be stronger

If there is more dissolving what does that mean for the ions

There are more ions

If a bond is strong what does Hcl turn into

No3

What does Hcl do in real world situations and what is it used for

It is very strong and used to clean concrete, break down molecules in digestion, and can be found in stomach acid.

What does strong mean with ionization?

Weak ionic bonds to water, dissolves and makes tons of ions

What does weak mean with ionization

It means it dissolves less and only makes few ions

What are strong acid examples

Hcl, Hno3, and H2SO4

Weak acid examples

Everything besides the big three, but especially NH3, organic acids, or anything insoluble

HNO3 uses

Nictric acid used to stain and rip jeans

H2SO4 uses

sulfuric acid, very corrosive, used in batteries

Polyprotic Acids

Has many protons and multiples H+(2+). They are very strong (H2SO4, H3PO4, H2CO3) To find there H30 double the M.

Equilibrium

No visible change, at molecular level.Are not required to have the same amount in each container in order to be in an equilibrium.

Are closed or opened reactions reversible?

Closed

What must happen between ions for a reaction to occur?

The ions must collide.

When do the forward and reverse actions stop?

When it becomes an equilibrium, represented by overlapping arrows. This is when the rate of the forward reaction = the rate of the reverse reaction.

What is necessary for a closed system.

all product is collected within, none is let out

Can an open system reach equilibrium

No, all the product must stay together

How does a successful reaction occur?

There is enough energy and good geometry

Does the forward or reverse reaction happen more easily?

Forward, it also happens faster

Which system allows products to collide with one another?

A closed system, this is not possible with an open system.

Can the rate of reaction be measured?

yes

What does k represent in a reaction?

the slope of the line on a graph

What is the equilibrium formula?

rate of forward reaction=rate of reverse reaction

Do solids or liquids have variable concentrations? If so/not what does this mean?

No they do not. It means you only include gases and aqueous.

Can solids/liquids change their concentration

No

What do the brackets represent?

concentration

What is the base forward rate?

k [h2} [I2]

what is the base reverse rate?

k [HI] [HI]

What is the keq formula?

product over reactant, coefficients to exponents

Do you use brackets with keq?

yes

What is the keq unit?

M

Do you include solids and liquids in keq?

No

Is the forward reaction always easier?

No, it depends on the amount of product and reactant.

What makes forward easier?

More product

What makes reverse easier?

more reactant

keq shows ratio of concentration of ___ at equilibrium?

reactant

Big keq

bigger than 1, (more product), forward reaction is easier,very fast reaction, mostly ions, lots of H30 → strong

Small keq

less than 1, (more reactant), reverse reaction is easier , very slow reaction, few ions, mostly undissociated molecules or weak acids. Only a little H30+ → mostly weak.

What does a acid+water make

hydronium+anion(salt)

What is the Ka of the very strongest acids?

infinity, indicating complete ionization in water.

If an acid is strong (the big three) what do you do?

it means it is a 1:1 ratio, you dont do math and write the M as the answer.

If the amount that breaks up is small what does this mean?

it means the acid is weak

If the amount that breaks up is large what does this mean?

It means it is strong

What does stress imply?

a change

Le Chateliers Principle

If you stress a system in equilibrium it will shift to counteract the stress.

Concentration

This is a stresser. Increasing concentration=shift toward products Decreasing concentration=shift toward reactants

Does pressure have an arrow circle?

no

What does volume stress?

gas (everything else is cancelled out)

If there is less molecules what does that mean?

less pressure

Is temperature a stresser?

Yes

Endothermic

Absorbs heat from surroundings (cold) (heat is reactant)

Exothermic

releases heat (hot) (heat is a product)

What is another name for optimum conditions

the haber process

common ion

has certain elements in common

Percent Ionization

amount that breaks up (x) / intial concentration of the acid (.100) (needs brackets)

do strong acids have a large or small percent ionization

large

do weak acids have a large or small percent ionization

small

If an acid is strong what percent ionization does it have?

100%

what is a equilibrium constant expression

a expression with k=product/reactant, but it is just the element in brackets

what does x represent

the change in concentration

If a question is looking for the hydronium ion concentration what is it really asking about?

ka

what acid is generally more corrosive, strong or weak

strong

do strong acids fully dissociate

yes

Are strong acids ALWAYS more corrosive

no, they can be less corrosive depending on the weak acids concentration, reactivity and acidity.

what does ka represent

acid dissociate constant

what does keq represent

equilibrium constant

is ka mono or poly

monoprotic (single proton dissociation)

is keq mono or poly

polyprotic (multiple proton dissociation)

when searching for a [ ] what do you set the anwer equal to?

[x]=

what unit must everything be in before keq or ka

M

what does cr mean

crystalline

keq formula

keq=product/reactant

ka formula

ka= x2/a-x

with keq what is the calculation shortcut

switch the keq with the bottom 1st x (or with exponent)

when looking for sig figs can the scientific formula be included

yes

if your searching for an element in a bracket are you looking for ka or keq

ka (or using ka if given)

How many ions does a big Ka value make?

It makes a lot

Chemicals that dissolve and form ions are called what?

Electrolytes

why do reactions happen

1. release stored energy = minimize enthalpy.

2. drive to gain raindomness or maximize entropy

delta G

gibbs free energy, tells if the reaction is spontaneous or not

What reaction needs a lot of activation energy from the start to bump it up?

endothermic

What reaction does not need a lot of activation energy and it starts high?

exothermic reaction

what are phase changes

a change in state, either by addition or removal heat

what happens to the temperature during a phase change

It stays consistent. Temperature is a measure of the average kinetic energy of particles. During a phase change, the energy being added or removed is not used to increase or decrease the kinetic energy (and thus temperature), but instead to break or form intermolecular forces.

temperature is a measure of what

kinetic energy

what do the flat parts of the graph represent

phase change

When are the slopes melting/freezing v vaporize/condense

melting/freezing if the lower energy (toward the bottom) and metling goes down, freezing goes up. higher energy is vaporize/condense and vaporize goes down condense goes up

what is delta PE

constant temp

what is delta ke

varying temp