C13-15 GROUPS RATES, HEAT CHANGES Flashcards Preview

Chemistry GCSE > C13-15 GROUPS RATES, HEAT CHANGES > Flashcards

Flashcards in C13-15 GROUPS RATES, HEAT CHANGES Deck (58)
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1
Q

alkali metals

A

the name of the metals in group 1 - lithium , sodium , potassium and so on

2
Q

group 1 symbols

A

li - lithium
Na - sodium
K - potassium

3
Q

reactions of alkali metals with water

A

metal + water - metal hydroxide + hydrogen

4
Q

lithium and water

A

lithium floats and bubble vigorously

5
Q

sodium and water

A

sodium melts into a ball and moves around the surface bubbling vigorously

6
Q

potassium and water

A

potassium melts into a ball , catches fire and moves around the surface bubbling vigorously

7
Q

group 1 reactivity

A

reactivity increases as you move down the group

8
Q

explaining group 1 activity

A

when metals react they lose their outer electrons. further down the group there are more shells of electrons so the outer electrons are less attracted to the nucleus and easier to move

9
Q

halogens

A

the names given to the non-metals in group 7- fluorine, chlorine , bromine and iodine

10
Q

chlorine

A

CL2 a pale green gas

11
Q

bromine

A

BR2 a red brown liquid

12
Q

iodine

A

l2 a shiny purple black solid

13
Q

reaction of halogens with metals

A

halogen + metal - metal halide

14
Q

reactions of halogens with hydrogen

A

halogen + hydrogen - hydrogen halide

15
Q

hydrogen halides

A

hydrogen halides dissolve in water to form acids, for example hydrogen chloride makes hydrochloric acid

16
Q

chlorine test

A

chlorine gas turns damp blue litmus red then quickly bleaches it white

17
Q

group 7 activity

A

reactivity increases as you go up the group

18
Q

explaining group 7 reactivity

A

when non-metals react they complete their outer shells. further up the group the elements have fewer shells so the nucleus attracts electrons more strongly

19
Q

displacement reactions

A

reactions in which a more reactive metal displaces a less reactive metal from a salt eg.
copper sulfate + zinc - zinc sulfate + copper
does not work backwards as copper is less reactive than zinc

20
Q

displacement reactions of halogens

A

a more reactive halogen displaces a less reactive halide ion by taking its electrons

21
Q

redox reactions of halogens

A

the more reactive halogen oxides the less reactive halide by taking its electrons. the more reactive halogen is reduced

22
Q

noble gases

A

the name given to the non-metals in group 0 - helium , neon, argon, krypton and xenon

23
Q

melting point of noble gases

A

they are all gases at room temperature but the melting and boiling point increase down the group

24
Q

reactivity of group 0

A

the noble gases do not (easily) do any reactions - they are inert

25
Q

explaining reactivity of group 0

A

when elements react they try to complete their outer shells because group 0 outer shell are already complete , they do not react

26
Q

uses of noble gases

A

hellium is used in airships because it is inhert and has low density
argon is used in fire extinguishers because it is inhert and denser than air
mean is used in lighting because it glows red when electricity is passed through it

27
Q

rate of reaction

A

the rate at which reactants are used up or products are made

28
Q

reactants vs time graphs

A

starts high and curves downward , decreasing rapidly at first and then more gently. steeper line = faster rate

29
Q

products vs time graph

A

starts low and curves upwards, increasing rapidly at first and then more gently. steeper line = faster rate

30
Q

measuring rates - reactions that produce gas

A

collect gas in a gas syringe and measurlthe volume every 30 seconds
collect gas over water and measure volume every 30 secs
do not reaction on a balance and record the change in mass every 30 secs

31
Q

measuring rates - reactions that go cloudy

A

do the reaction in a beaker placed on piece of paper with a cross marked on it looking down through the beaker , time how it takes for the crops to disappear

32
Q

collision theory

A

states for two particles to react they must:
collide with each other
collide with enough energy to react

33
Q

activation energy

A

the minimum energy that two particles must have when they collide in order to react

34
Q

effect of concentration on rate

A

increasing the concentration increase the rate because there are more particles so there are more collisions and more reactions

35
Q

effects of surface area on rate

A

increasing the surface area (by decreasing particle sizes) in creases the rate by exposing more particles to collisions leading to more collisions and more reactions

36
Q

effect of pressure on rate

A

increasing the pressure increases the rate because particles are pushed closer together sp they collide more often

37
Q

effect of temperature rate

A

increasing the temperature increases the rate because particles move faster so they collide more , and collide with more energy to a greater proportion to collisions lead to reactions

38
Q

catalyst

A

a substance that speeds up a chemical reaction without being used up

39
Q

effects of catalysts on rate

A

catalysts increase the rate of reaction by reducing the activation energy so that a greater proportion of collisions lead to reactions

40
Q

reaction profile

A

a graph that shows the changes in energy during a reaction starts with large ‘hump’ that represents the activation energy

41
Q

effects of catalysts on reaction profiles

A

the hump representing the activation energy is smaller

42
Q

enzyme

A

a protein that works as a catalyst to speed up the reactions in our cells

43
Q

enzymes in alcohol production

A

alcoholic drinks are produced using enzymes found in yeast which catalyst a reaction that urns glucose into ethanol

44
Q

exothermic reactions

A

a reaction that transfers energy to the surroundings( gets hotter)

45
Q

exothermic reaction examples

A
neutralisation 
displacement 
combustion 
some precipitation 
respiration
46
Q

endothermic reaction

A

a reaction that absorbs energy from the surroundings

47
Q

endothermic reaction examples

A

dissolving (most) salts
some precipitation
photosynthesis

48
Q

exothermic reaction profile

A

the reactants have more energy than the products so their line on the graph is higher

49
Q

endothermic reaction profile

A

the reactants have less energy than the products so their line on the graph is lower

50
Q

measuring energy changes

A

sit a polystyrene beder inside a glass beaker (insulation)
measure the starting temperature of the reactants
mix the reactants in the polystyrene beaker
cover the lid fitted with a thermometer
monitor and record the lowest temperature q

51
Q

chemical bonds in reaction.

A

during chemical reactions , old chemical bonds are broken and new ones are formed

52
Q

breaking bonds

A

breaking bonds absorbs energy breaking stronger bonds absorbed more energy

53
Q

making bonds

A

making bonds releases energy making stronger bonds releases more energy

54
Q

energy changes and bond information

A

the energy change in a reaction is the difference between the energy required to break the old bonds and the energy released by making the ew ones

55
Q

exothermic reactions and bonds

A

exothermic reactions break weaker bonds and make stronger ones

56
Q

endothermic reactions and bonds

A

endothermic reactions break stronger bonds and make weaker ones

57
Q

bond strengths

A

the energy required to break one mole of a particular covalent bond in kj/mol

58
Q

calculating energy changes from bond strength

A

add up the total strength of old bonds broken and subtract the total strength of new bonds made. a negative answer is a exothermic