Chemistry Exam 4

Contains Chapters 14B-16

What a buffer solution is made of?

a weak acid and its conjugate base or a weak base and its conjugate acid.

How the pH of a buffer solution will change upon adding strong acid?

There will be a little decrease in ph.

How the pH of a buffer solution will change upon adding a strong base?

There will be a little increase in ph.

Buffer capacity

the moles of an acid or base necessary to change the pH of a solution by 1

How does the pH change during a strong acid/strong base titration?

the acid and base will react to form a neutral solution (pH of 7)

How does the pH change during a weak acid/strong base titration?

There is a sharp increase in pH at the beginning of the titration, then there is a gradual increase.

What is an acid-base indicator?

A compound that changes color at the end point of a reaction

End point

the conclusion of a chemical reaction

Equivalence point

When the mols of acid is equal to the moles of base

How does the solubility product constant (Ksp) relates to solubility of a slightly soluble ionic compound in water.

The Ksp of a substance is higher the more soluble the substance is

If the Qsp > Ksp, will the solution have precipitate?

Yes, precipitate will form

If the Qsp = Ksp, will the solution have precipitate?

Yes, precipitate will form

If the Qsp < Ksp, will the solution have precipitate?

No, precipitate will not form

How the addition of a common ion changes the molar solubility of a slightly soluble ionic compound?

the solubility of any sparingly soluble salt is almost always decreased by the presence of a soluble salt that contains a common ion.

Spontaneous

proceeds in a certain direction with no external energy needed

Nonspontaneous

Does not react unless external energy is added to it

If a reaction is spontaneous in one direction is spontaneous the other way?

No, it is not.

How is entropy related to freedom of motion?

The more freedom of motion the higher the entropy

How is entropy related to the number of possible microstates?

the greater the number of possible microstates and the higher the entropy

If the temperature increases then entropy…

… increases

List the states of matter from least entropy to most entropy.

Solid, Liquid, Gas

Entropy increases when you dissolve a ---- solvent.

solid or liquid

Entropy decreases when you dissolve a ---- solvent.

gas

True or False:

The larger the atom (of the same physical state) the larger the standard entropy

True

True or False:

The more complex an atom the lower the standard entropy

False

Second Law of Thermodynamics

All real processes occur spontaneously in the direction that increases the entropy of the universe.

Third Law of Thermodynamics

A perfect crystal has zero entropy at absolute zero.

When ΔSuniv > 0, the reaction is…

spontaneous

When ΔSuniv = 0, the reaction is…

at equilibrium

When ΔSuniv < 0, the reaction is…

Nonspontaneous

If a reaction is spontaneous then its Gibbs Free Energy is…

Less than zero (ΔG < 0)

If a reaction is not spontaneous then its Gibbs Free Energy is…

Greater than zero (ΔG > 0)

If a reaction is at equilibrium then its Gibbs Free Energy is…

Equal to zero (ΔG = 0)

If ΔH is positive and ΔS is negative then the reaction is…

never spontaneous

If ΔH is negative and ΔS is positive then the reaction is…

always spontaneous

If both ΔH and ΔS are negative then…

the reaction is only spontaneous at low temperatures

If both ΔH and ΔS are positive then…

the reaction is only spontaneous at high temperatures