1) Chemical Changes and Structures

Question 1

Ways of speeding up rate of reaction (4)

Answer 1

using a catalyst
decreasing particle size // increasing surface area
increasing temperature
increasing concentration / pressure

Question 2

Ways of measuring rate of reaction (3)

Answer 2

water displacement (vol gas produced)
gas syringe (vol gas produced)
difference in mass (vol mass change)

Question 3

Why is it important that chemists can control rate of reaction? (2)

Answer 3

• to ensure that processes are both economically viable (they will result in a good yield of products and profits for the company)
• to ensure it is safe (the reaction does not progress too quickly potentially causing explosions).

Question 4

The rate of a chemical reaction is proportional to the

Answer 4

concentration of reactants present. As reactants are used up during the process, the rate will decrease, and the reaction slows down.

Question 5

ΔQ can be a: (3)

Answer 5

volume
mass
concentration / pressure

Question 6

For a successful collision you need: (2)

Answer 6

activation energy

correct geometry

Question 7

What does a catalyst do when added to a chemical reaction?

Answer 7

It lowers the activation energy, allowing more reactions to occur.

Question 8

ΔH = ?

Answer 8

ΔH = Hproducts - Hreactants

Question 9

What is the activated complex?

Answer 9

The unstable arrangement of atoms which is very high in energy.

Question 10

What is ΔH?

Answer 10

enthlapy change

Question 11

In an exothermic reaction is ΔH positive or negative?

Answer 11

negative

Question 12

In an endothermic reaction is ΔH positive or negative?

Answer 12

positive

Question 13

Why does increasing temperature increase rate of reaction?

Answer 13

Because more particles now have energy greater than or equal to the activation energy

Question 14

Why does increasing concentration or pressure increase rate of reaction?

Answer 14

More of these reactant particles are moving in the same space making it more likely than before that they will collide and cause a successful collision

Question 15

Collision theory states that

Answer 15

reactants must collide with the correct geometry and possess a minimum energy before a successful collision occurs

Question 16

Characteristics of metallic lattice: (3)

Answer 16

strong bond, high melting point, good conductors

Question 17

as we look from the _________ to the _________ of the periodic table we see COVALENT RADIUS increasing

Answer 17

top right to bottom left

Question 18

as we look from the _________ to the _________ of the periodic table we see 1ST IONISATION ENERGY increasing

Answer 18

bottom left to top right

Question 19

as we look from the _________ to the _________ of the periodic table we see ELECTRONEGATIVITY increasing

Answer 19

bottom left to top right

Question 20

hydration is an example of a _____ reaction

Answer 20

addition

Question 21

what is the activated complex

Answer 21

a high-energy unstable arrangement of atoms

Question 22

the more level the potential energy diagram

Answer 22

the more stable the activated complex

Question 23

Reminder: the greatest enthalpy change doesn’t have to be positive

Answer 23

the greatest enthalpy change doesn’t have to be positive

Question 24

when liquid oxygen evaporates what forces are broken

Answer 24

London dispersion forces

Question 25

what is the ionisation energy

Answer 25

the energy required to remove one more of electrons form one mole of gaseous atoms

Question 26

an increase in ___________ causes the electrons to be more attracted to the nucleus

Answer 26

nuclear charge

Question 27

an increase in __________ causes the outer electrons to be screened for the nucleus

Answer 27

electron shells

Question 28

ionic vs covalent: how can you tell (3)

Answer 28

ionic compounds conduct when molten/ in liquid while covalent do not
ionic compounds tend to have high melting points as a lot of energy is required to break their strong ionic bonds in the lattice.
ionic compounds are usually water soluble

Question 29

what is a type of bonding that is never found in elements

Answer 29

polar covalent

Question 30

three types of bonding found in elements are

Answer 30

metallic
ldf
non polar covalent

Question 31

is covalent bonding a van der waals force?

Answer 31

no

Question 32

three types of van der waal forces

Answer 32

hydrogen bonding
ldf
pdpd interactions

Question 33

does a catalyst provide energy

Answer 33

no

Question 34

what three things does a catalyst do

Answer 34

lowers the activation energy that molecules need for successful collisions
provides an alternative route to the products
forms bonds with reacting molecules

Question 35

Reminder: when Q asks for arrangement of amino acids in a peptide - the set does not have to be in order

Answer 35

when Q asks for arrangement of amino acids in a peptide - the set does not have to be in order

Question 36

Reminder: when Q asks for a good solvent look for polar functional groups in given molecule. if it has any then look for most polar choice. if it doesn’t then look for least polar choice

Answer 36

when Q asks for a good solvent look for polar functional groups in given molecule. if it has any then look for most polar choice. if it doesn’t then look for least polar choice

Question 37

For Q where substance A burnt to produce x energy + calc volume substance B to produce same x amount of energy. What is equation
GIVEN:
substance A:
volume (burnt)
energy (produced)
substance B:
volume (of 1g)
energy (of 1g)

Answer 37

(A energy prod/ B energy of 1g) x B volume of 1g