Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

EA PREP > chemistry U3 T1 > Flashcards

chemistry U3 T1 Flashcards

1
Q

definition dynamic equilibrium?

A

balance is maintained and reaction is continuously happening. Reactants and products are being created/used up continuously at the same rate so forwards and reverse reactions are equal.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

definition; open system

A

reaction vessel with no lid so matter and energy can escape

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

definition closed system

A

reaction vessel has a lid so matter can escape but not energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what does increasing volume do

A

decrease pressure, decrease concentration thus equilibrium moves to side w/ more moles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what does decreasing volume do

A

increase pressure, increase concentration thus equilibrium moves to side w/ less moles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

definition; le chatliers principle

A

if an equilibrium system is subject to change the system will adjust proportionally to oppose the change

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what causes a disturbance

A

volume
pressure (only gas form)
temperature
adding or removing substances
diluting aqueous solution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

definition; temperature

A

measure of average kinetic energy in a system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

for endo and exo, which is a positive H (enthalpy change)? What side is heat on?

A

endo positive (left), exo negative (right)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

endo vs exo?

A

endo absorbs heat and cools surroundings
exo releases heat and heats surroundings

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

3 things that dont change equilibrium position?

A
  1. Catalyst as it lowers activation energy and speeds up reactions however it doesnt change equilibrium position.
  2. Changing temperature with H=0 (0 enthalpy) as its neither endo or exo.
  3. Changing pressure w/ equal moles on either side.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is Kc? What does <1> mean?

A

Its the ratio of reactants to products when reaction is at equilibrium.
Less than 1 is reactants favoured
More than 1 is products favoured

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is Kc for a reverse reaction (formula)?

A

Kc (reverse)= 1/Kc (forwards)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What can change Kc?

A

temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

definition; proton donor

A

Substance that can donate H^+ (hydrogen ion)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

definition; monoprotic acid

A

acid that can donate 1 H+ (hydrogen ion) per molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

definition; polyprotic acid

A

acid that can donate 2+ H+ (hydrogen ion) per molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Acid vs base?

A

acid donates protons
base accepts protons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Strong vs weak acids/bases?

A

strong completely dissociate (ionisation) (releasing all H+)
weak partially dissociate (releasing some H+)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

concentrate vs dilute acids/bases?

A

concentrate has high concentration/molarity and large amounts are dissolved in a solution
dilute has low concentration/molarity and small amounts are dissolved in a solution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Whats an electrolyte?

A

substance that conducts electricity when melted or dissolved in a solution. Conductivity in a solution depends entirely on the presence of charged particles.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what solutions conduct electricity best to worst? Why?

A

the one with most hydrogen ions conducts the best. so;
Concentrated strong acid > concentrated weak/dilute strong > dilute weak

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is water’s self-ionisation reaction (unlikely)? What regularly occurs?

A

2 H2O <-> H3O+ + OH-

H2O <-> H+ + OH-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is Kw?

A

the equilibrium constant of self-ionisation of water.

25
Q

Definiton; Qc? What does it mean when comparing Qc to Kc?

A

is the reaction quotient, measure of the relative amounts of products and reactants present in a reaction at a given time (calculated the same way as Kc).
if Qc is bigger than Kc - too many products
if Qc is smaller than Kc - too many reactants

26
Q

Definition; pH?

A

is a measure of hydrogen ion concentration in a solution and therefore a measure of acidity or alkalinity of a solution

27
Q

Definition; pOH?

A

is a measure of hydroxide ion concentration in a solution and therefore a measure of the basicity of a solution

28
Q

What equals 14?

A

pOH + pH

29
Q

What is a conjugate acid and base?

A

Conjugate acid is an acid formed after a base accept an H+ (originally a base, then accepts proton (H+), now conj base)
Conjugate base is a base formed when an acid loses an H+ (originally acid, then donated a proton, now conj base)

30
Q

Identify the conjugate pair?

A

HA + B <-> A- + HB+
Acid + base <-> conj. base + conj acid

so acid and conj base/HA and A- = pair
base and conj acid/ B and HB+ = pair

31
Q

Definition; Amphiprotic? 2 Examples?

A

is a molecule or ion that can either donate or accept a proton so can act as acid or base. e.g. HCO3^- and H2O

32
Q

Conjugate Acid and base strengths?

A

Strong acid -> very weak base
weak acid <-> weak base
Strong base -> very weak acid

33
Q

What pair type forms equilibrium reactions?

A

weak acid <-> weak base

34
Q

Strongs acids (3)

A

H2SO4 - sulphuric
HCl - hyrochloric
HNO3 - nitric

35
Q

Strong Bases (2)

A

Any group 1 + Hydroxide
Barium + hydroxide

36
Q

Weak acids (3)

A

H2CO3 - carbonic
HCO3 - hydrogen carbonate ion
R COOH

37
Q

Weak bases (3)

A

NH3 - ammonia
R NH2
R NH R

38
Q

Definition; buffer solutions?

A

is a solution that resists changes in pH when small quantities of acids or bases are added. It contains appreciable amounts of 1 - weak acids and its conjugate base, 2 - weak base and its conjugate acid

39
Q

Example of a mixture of weak acid with salt of its conjugate base

A

acetic acid/ sodium acetate

40
Q

Example of a mixture of weak base with salt of its conjugate acid

A

ammonia/ ammonium chloride

41
Q

How do buffers work? (2)

A
  1. when a strong base is added, the acid present in the buffer neutralise the OH-
  2. When a strong acid is added, the base present in the buffer neutralise the H3O+
42
Q

Definition; Ka?

A

equilibrium constant for the dissociation of an acid in an aqueous solution

43
Q

Definition; Kb?

A

equilibrium constant for the dissociation of a base in an aqueous solution

44
Q

What do lower and higher levels of Ka and Kb mean?

A

High Ka/b means more products and more dissociation
Lower Ka/b means less products and less dissociation

45
Q

If using a weak acid indicator e.g. HA (blue) + H2O <-> A- (red) + H3O+ in acidic and then basic conditions, what would happen?

A

Acidic conditions; [H3O+] increases, pushes equilibrium left creating more [HA], and colour would be blue.

Basic conditions; [H3O+] decreases, pushes equilibrium right creating more [A-], and colour would be red.

46
Q

If using a weak base indicator e.g. B (blue) + H2O <-> BH+ (red) + OH- in acidic and then basic conditions, what would happen?

A

Acidic conditions; [OH-] decreases, pushes equilibrium right creating more [BH+], and colour would be red.

Basic conditions; [OH-] increases, pushes equilibrium left creating more [B], and colour would be blue.

47
Q

What is equivalence point?

A

the point in a titration when the reactants have reacted in the molar ratio of the balanced chemical equation.

48
Q

Ka/b and PKa/b of stronger acids/bases vs weak acids/bases

A

Strong: have higher Ka/b values and lower PKa/b values
Weak: have lower Ka/b values and higher PKa/b values

49
Q

Neutralisation reactions?

A

acid + base -> salt + water

50
Q

Analyte vs titrant?

A

Analyte is an unknown concentration of solution (often in flask)
Titrant is a known concentration (often in burette)

51
Q

Stoic formula?

A

n=cv

52
Q

What is the buffer region?

A

pH=pKa in weak acid and pOH=pKb in weak base

53
Q

Provide an example of a physical and chemical change?

A

melting ice
harber process forming NH3, acid dissociation

54
Q

As heat energy is applied to a solid, what occurs to its kinetic energy and the changes that take it from s to l to g?

A

As heat increases so does kinetic energy. Particles vibrate out of the orderly structure of a solid and start moving with the containing (l form). If enough energy is supplied to counteract intermolecular forces and ionic bonds, particles are separated and form gases.

55
Q

P71 Q6, P72 Q20a, P48 Q3&4

A
56
Q

If increasing temperature increased Kc from 0.32 to 0.88, was the reaction endo or exo?

A

endo

57
Q

If you have N2 + O2 -> 2NO and it was at equilibrium what would happen?

A

2 moles of gas on left and right so the increased volume would increase concentration but position of equilibrium would not change

58
Q

P72 Q16, P71 Q7

A

EA PREP (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions