Brainscape's Knowledge GenomeTM

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


See full index

chemistry yr 11 > mod 4 > Flashcards

mod 4 Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Chemistry flashcards Periodic Table flashcards Chemistry 101 flashcards Organic Chemistry 101 flashcards
1
Q

Energy is absorbed to ___
Energy is released to ___

A

break bonds (endothermic)
create bonds (exothermic)

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

What is dissolution?

A

when a solute dissolves in a solvent to form a solution using 3 processes
1. solute-solute interactions are broken (endo needs energy)
2. solvent-solvent interactions are broken (endo needs energy)
3. solute-solvent interactions are formed (exo releases energy)

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

What do solute-solvent interactions do?

A

called salvation or hydration when the water/solvent creates concentric rings/hydration spheres around ions and ion-dipole forces bond them together

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

What is a salt that endothermically dissolves?

A

NaOH

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

What is a salt that exothermically dissolves?

A

KCl

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

What is the molar heat of a solution?

A

heat released or absorbed upon the dissolution of a substance measured in J or kJ per mole
molar heat in endo = q/n
molar heat in exo = -q/n
(q = energy/heat released or absorbed in J or kJ)
(n = moles of substance)

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

What is enthalpy (H)?

A

is the amount of stored heat within a substance. only CHANGE of enthalpy can be measured using
change in enthalpy = sum of change in enthalpy of products - sum of change in enthalpy of reactants

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

What are the two types of enthalpies?

A

exothermic means change in H < 0
endothermic means change in H > 0

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

Manipulating enthalpy equations:

A

if you multiply or divide or change ratios of the coeff’s in a chemical equation, you must do the same to the enthalpy

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

How can heat released be measured in a calorimetry experiment?

A

q = m x c x change in T
(q = energy released in J)
(m = mass of solvent/water in g) (can use density and mL to get mass)
(c = specific heat capacity, e.g in water it is 4.18g/K)
(T = temperature in kelvin)

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

What factors affect calorimetry experiments?

A

some heat can be lost via conduction
we assume reactions are complete combustions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is Hess’s Law?

A

he states that the enthalpy change accompanying a chemical change is independent of the route by which it occurs
change in H = change in H1 + change in H2 + change in H3

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

What is enthalpy of formation?

A

is the change of the formation of product (coeff should be 1) in its STP

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

Which elements have 0kJ at STP?

A

H2
N2
F2
O2
I2
Cl2
Br2

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

How can you manipulate thermochemical equations?

A
  1. multiply equations = multiply change in H
  2. reverse equations = flip change in H sign
  3. add equations = add change in H
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the two types of catalysts?

A

Homogenous and Heterogenous

17
Q

What are homogenous catalysts?

A

are in the same phase/state as reactants (in l, aq or g)
1. the catalyst reactions with one or more of the reactants to create a temporary intermediate
2. the intermediate reacts with the other reactants
3. it then decomposes to form the products and regenerates the catalyst (NOT consumed)
- If a substance is on both reactant and product side, it is a catalyst
- if a substance is formed and then gone it is an intermediate

18
Q

What is a heterogenous catalyst?

A

are in different phases/states to the reactants (in s, l, aq or g)
1. reactants absorb/stick to the catalyst at a specific active site which causes their reactions to speed up (happens on the catalyst surface)
2. the products then desorb
- an intermediate may or may not be created

19
Q

What is bond enthalpy?

A

refers to the amount of energy needed to break 1 mole of a certain type of bond into its constituent gaseous atoms (endo)
- higher the bond energy, the more bonds needed to be broken
- there is a table of bond energy

20
Q

How to calculate bond enthalpy?

A
  1. write the chemical equation
  2. draw table
    - (bond-breaking and bond forming on y-axis)
    - (no/type of bonds and energy on x-axis)
  3. change in bond enthalpy = change in bond breaking + change in bond forming
21
Q

What is the Haber process?

A

process that involves the production of ammonia from its constituent gas elements
1/2N2(g)+3/2H2(g) == NH3(g)
- heterogenous Fe3O4(s) is a catalyst

22
Q

What is entropy?

A

the amount of randomness of disorder in a substance
- absolute entropy can be measured
- change in entropy = sum of products entropy - sum of reactant entropy

23
Q

What is the standard molar entropy? (S)

A

the entropy of one mole of a substance at STP in unit J

24
Q

What is the second law of thermodynamics?

A

states that a SPONTANEOUS reaction will occur naturally without an ongoing supply of heat

25
Q

Entropy trends:

A
  • increase in MM = increase in entropy
  • entropy of (g)>(l)>(aq)>(s)
  • increase entropy with increase in chemical complexity
26
Q

Entropy trends:

A
  • increase in MM = increase in entropy
  • entropy of (g)>(l)>(aq)>(s)
  • increase entropy with increase in chemical complexity
27
Q

What are the drivers of reaction?

A
  • entropy drive (forward = S>0, reverse = S<0)
  • enthalpy drive (forward = H<0, reverse = H>0)
28
Q

What is Gibbs free energy?

A

the change in gibbs free energy (change in G) is the maximum amount of work that can be performed during a chemical reaction (in J)
- only change can be measured
- if G<0 spontaneous
- if G>0 non-spontaneous
- if G=0 equilibrium

29
Q

How to measure change in G?

A
  • change in G under STP = (change in H) - T(change in S)
  • change in G = (change in H) - (change in S)
  • change in G = (sum of change in products G) - (sum of change in reactants G)
30
Q

Low activation energy required =

A

spontaneous reaction

31
Q

What is a state function?

A

the values which depend on the state of the substance, like temperature, pressure or the amount or type of the substance (e.g Hess’ law says enthalpy is independent of the pathway)

32
Q

What is a path function?

A

properties or quantities whose values depend on the transition of a system from the initial state to the final state (pathway it takes) (e.g heat and work)

33
Q

Photosynthesis:
Respiration:

A

6CO2 + 6H2O → C6H12O6 + 6O2 (endo)
C6H12O6 + 6O2 → 6CO2 + 6H2O (exo)

34
Q

What is the first law of thermodynamics?

A

energy cannot be created or destroyed; it can only be converted from one form to another.

35
Q

When does a reaction occur (entropy)?

A

change is system entropy + change in surroundings entropy = change in universe entropy >0
- reaction only occurs when change in universe entropy >0

36
Q

What affects entropy?

A

increased molecular weight, temperature, complexity
decreased pressure/concentration

chemistry yr 11 (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions