Test 1 (13 - 24)

Question 1

Water ion constant

Answer 1

You can also use it to calculate the H30^+ or OH^- in the solution.

[OH^-] = Kw / [H3O^+]

[H3O^+] = Kw / [OH^-]

Question 2

How to know if a solution is acidic, basic or neutral?

Answer 2

Question 3

How to get pH?

Answer 3

Acid:
- Log of [H3O^+]
=pH

Base:
- log of [OH^-]
=pOH
14 - pOH
=pH

Question 4

What are indicators?

Answer 4

compounds that dramatically change color when the
pH of the solution changes.

frequently weak acids or weak bases, which protonated (conjugate acid form) and deprotonated (conjugate base form) forms have different colors.

Question 5

Indicators, K constant and what is prevalent/dominating in which solution?

Answer 5

In an acidic solution the protonated form (HIn) is prevalent, wheras in a basic solutions the deprotonated form (In-) is dominating.

Question 6

How pk is obtained for indicators

Answer 6

Question 7

Indicator equilibrium shifting when H3O^+ is added and when OH^- is added

Answer 7

Question 8

What are buffers?

Answer 8

A buffer solution is a solution that maintains pH by neutralizing
added acid or bases.

Question 9

What is buffer capacity?

Answer 9

quantity (number of moles) of
strong acid or base that must be
added to change the pH of one
liter of buffer solution by one pH
unit.

Question 10

What is an acidic buffer?

Answer 10

a weak acid (HA) and its conjugate base (A−)

Question 11

What is a basic buffer?

Answer 11

a weak base (B) and its conjugate acid (BH+)

Question 12

How to calculate pH of a acidic buffer?

Answer 12

Question 13

How to calculate pH of a basic buffer?

Answer 13

Then later 14 - pOH = pH

Question 14

What are electrolytes?

Answer 14

after dissolving in water they separate into ions that conduct electricity

Question 15

What are nonelectrolytes?

Answer 15

dissolve in water as molecules, not as ions, their solutions do not conduct electricity.

Question 16

Strong and weak electrolytes

Answer 16

Weak electrolytes have a dissociation degree (a) of a <0,05
Weak acids and bases

Strong electrolytes have a dissociation degree 0,3 < a <1
Salts, strong acids and bases

Question 17

How can you calculate the dissociation degree (a) of electrolytes?

Answer 17

a = n/n0
or
a = n/n0 * 100%

n = number of moles of original solute molecules that have dissociated
n0 = number of moles of original solute molecules (total)

Question 18

Electrolytes classification(with qualities)

Answer 18

Question 19

How do you count equivalents in electrolytes?

Answer 19

Based on the ion charge.

1 mole of Na+ → 1 Eq
1 mole of Ca2+ → 2 Eq
1 mole of Fe3+ → 3 Eq

Question 20

What is the collision theory?

Answer 20

A reaction takes place only when molecules collide with the
proper orientation and with sufficient energy.

Only a few actually lead to the formation of product

Question 21

What is activation energy?

Answer 21

The minimum amount of energy
required to break the bonds between atoms of reactants and
form all new bonds.

Question 22

Heat of reaction

Answer 22

DH (enthalpy change)

Question 23

What is an exothermic reaction?

Answer 23

the energy of the reactants is greater than
the energy of the products. Heat is released along with the
product formation.

ΔH < 0
reactans → products + energy

Question 24

What is an endothermic reaction?

Answer 24

the energy of the reactants is lower than the energy of the products. Heat is absorbed and used to convert the reactants to the products.

ΔH > 0
reactants + energy → products

Question 25

What type of reaction is this?

Answer 25

Endothermic

Question 26

What type of reaction is this?

Answer 26

Exothermic

Question 27

What is reaction rate? How to calculate?

Answer 27

determined by measuring the amount of a reactant used up, or the amount of a product formed, in a certain period of time.

Question 28

Reaction rate - temperature

Answer 28

At higher temperature the reacting molecules move faster, more collisions occur and more colliding molecules have sufficient energy to react and form product → the reaction rate increase.

Question 29

Reaction rate - concentration

Answer 29

Increasing the concentration, increases the probability of a collision between reactant particles because there are more of them in the same volume and so increases the chance of a fruitful collision forming products → the reaction rate increase.

Question 30

Reaction rate - catalyst

Answer 30

Lowering the activation energy by catalyst is another way to speed up a reaction. The catalyst allows more collisions of the reactans to have sufficient energy to form products.

Question 31

Order of reaction

Answer 31

Question 32

What is elementary reaction?

Answer 32

single step reaction having a single transition state and no intermediates rate = k * [A]^a * [B]^b

Question 33

Elementary reaction molecularity of the reaction

Answer 33

the number of atoms, ions or molecules that must collide with one another simultaneously to result into a chemical reaction sum of the molecules of the different reactants.

Question 34

What is a complex reaction

Answer 34

a reaction with a complicated set of reaction steps.

Question 35

Complex reaction

Answer 35

When C -> D is slow, the rest of the reactions are fast

Question 36

Complex reaction - rate-determining step

Answer 36

A + B + C --> ABC (2 steps) A + B --> AB (slow) (will need 2 steps, therefore it's slow) AB + C --> ABC (fast)

Question 37

What is thermodynamics?

Answer 37

the study of the interrelationships among heat, work, and the energy content of a system at equilibrium.

Question 38

First law of thermodynamics

Answer 38

Heat Q and work W transferred into a thermodynamic system or transferred out of a thermodynamic system do not just disappear or appear out of nowhere. ΔU = Q + W

Question 39

What is enthalpy?

Answer 39

the sum of a system’s internal energy (U) and the mathematical product of its pressure (P) and volume (V) H = U + P * V

Question 40

Second law of thermodynamics

Answer 40

A spontaneous process is one that occurs naturally under certain conditions (can proceed with no outside intervention) - diffusion - decay of radioactive isotopes - hot metal cooling at room temperature A nonspontaneous process will not take place unless it is “driven” by the continual input of energy from an external source. - heating a metal - gas compression

Question 41

Third law of thermodynamics

Answer 41

A perfect crystal at zero Kelvin has zero entropy.

Question 42

What is enthropy (S) ?

Answer 42

Degree of disorder, depends on the number of microscopic states, or microstates, associated with it (in this case, the number of atoms or molecules) ΔSuniv = ΔSsys + ΔSsurr ΔSuniv > 0 spontaneous ΔSuniv < 0 nonspontaneous (spontaneous in opposite direction) ΔSuniv = 0 reversible (system is at equilibrium)

Question 43

What is Gibbs free energy?

Answer 43

a thermodynamic quantity equal to the enthalpy (of a system or process) minus the product of the entropy and the absolute temperature. enthalpy, temperature, and entropy: G = H − TS

Question 44

How the Gibbs energy looks for different quantities (spontaneous, non, reversible)

Answer 44

Question 45

Standard Gibbs free energy of reaction

Answer 45