paper 2 Flashcards
(87 cards)
1
Q
group one metal physical properties
A
low melting and boiling points
very soft
2
Q
alkali metals form…
A
ionic compounds , they loose their single outer electron so easily they cant form ionic bonds
3
Q
are group 1 metals reactive?
A
very reactive
4
Q
group one metals ____ their single outer eletron to form a ____ ion with a stable electronic structure
A
loose their single outer electron
forms 1+ ion
5
Q
the more easily a metal looses its outer electrons, the more
A
reactive it is
6
Q
in group one the outer electron is more easily lost because…
A
it’s further from the nucleus so it’s less strongly attracted to the nucleus and less energy is needed to remove it
7
Q
as you go down group 1 the alkai metals get _________ reactive
A
more reactive
8
Q
when alkali metals react w cold water what does it produce
A
produces a hydroxide and a hydrogen gas
9
Q
what test shows hydrogen being present
A
squeaky pop
10
Q
what reaction does alkali metals and water produce
A
produces hydrogen gas and a hydroxide of the metal
11
Q
what will lithium do in water
A
move around the surface, fuzzing furiously
12
Q
what will sodium and potassium do in water ?
A
move around and fizz + melt
potassium can even ignite the hydrogen gas being produced
13
Q
what are the group one metals
A
lithium, sodium, potassium, rubidium, caesium, francium
14
Q
what elements are in group 7
A
fluorine, chlorine, bromine, iodine, astatine
15
Q
how many electrons do group 7 have in their outer shell
A
7 electrons
16
Q
group 7 elements are known as ..
A
the halogens
17
Q
the halogens exist as
A
diatomic molecules (eg cl^2
18
Q
sharing one pair of electrons in a covalent bond gives both atoms a…
A
full outer shell
19
Q
as you go down group 7, the melting and boiling points of halogens…
A
increases
20
Q
chlorine characteristics
A
fairly reactive, poisonous green gas
21
Q
bromine characteristics
A
poisonous, red brown liquid, which gives off an orange vapour at room temperature
22
Q
iodine characteristics
A
dark grey crystalline solid which gives off a purple vapour when heated
23
Q
what is the test for chlorine?
A
damp blue litmus paper
chlorine will bleach the litmus paper turning it white , may turn red for a moment due to chlorines acidic
24
Q
reactivity of group 7 elements ______ going down
A
decrease
25
how many electrons does a halogen atom need to gain to from a 1- atom with a stable structure?
gain one electron
26
what makes a halogen easier to attract an electron?
the more reactive the halogen is
27
what can halogen react with?
metals and hydrogen
28
halogens will react vigorously with some metals to form…
salts called metal halides
29
halogens are more reactive the higher up the group is because…
they can attract the outer electron of the metal more easily
30
halogens can also react with hydrogen to form ..
hydrogen halides
31
hydrogen halides are soluble they can..
dissolve in water to form acidic solutions
32
the elements in group 7 take part in what reactions
displacement reactions
33
what is a displacement reaction
where a more reactive element displaces a less reactive element from a compound
34
what kind of reaction are halogen displacements ?
redox (oxidation and reduction occurs)
35
during halogen displacement, what happens
the halogens GAIN electrons (reduction) whilst halide ions lose electrons (oxidation)
36
what does OILRIG stand for
oxidation
is
loss (of electrons)
reduction
is
gain (of electrons)
37
how can displacement reactions show reactivity trends of halogens
measure out a small amount of halide salt solution in a test tube
add a few drops of a halogen solution to it and shake the tube gently
if you see a colour change then reaction has happened, halogen has displaced the halide ions from the salt
if no reaction happens then there’s no colour change , the halogen is less reactive than the halide and so it can’t displace it
repeat w different combos of halide salt and halogen
38
what does aq mean
aqueous , solution where the solvent is water
39
group 0 is the
noble gases
40
elements in group 0
helium, neon, argon, krypton, xenon and radon
41
all of group 0 are colourless gasses at…
room temperature
42
all noble gasses are monatomic gases , this means
their gases are made up of single atoms ( not molecules )
43
noble gasses are also inert, this means
they don’t react much this is because they have a full outer shell of electrons , this means they don’t easily give up for gain electrons
this means they are also non flammable
44
noble gasses can be used to provide an ..
inert atmosphere
45
argon creates an inert atmosphere by..
being in filament lamps , since it’s non flammable it stops the very hot filament from burning away
46
the boiling point, melting point and density all ______ as you go down group 0
increase
47
rate of reaction =
amount of reactant used or amount of product formed / time
48
3 experiments to follow reaction rates
precipitation , change in mass , volume of gas given off
49
precipitation experiment
mixing two see through solutions produces a precipitate which clouds the solution
1) mix the two reactant solutions and pour the flask on a peice of paper that has a mark on it
2) observe the mark through the mixture and measure how long it takes it for the mark to be obscured.
the faster it disappears the faster the reaction
50
change in mass experiment
as the gas is released the lost mass is easily measured on the mass balance
the quicker the reading on the balance drops, the faster the reaction
when the reading on the balance stops changing, the reaction has finished
plot a graph of change in mass against time
HARMFUL GAS RELEASED DO IN A FUME CUPBOARD
51
volume of gas given off experiment
this involves the use of a gas syringe to measure the volume of gas given off.
2) The more gas given off during a set time interval, the faster the reaction.
3) You can tell the reaction has finished when no more gas is produced.
4) You can use your results to plot a graph of gas volume against time elapsed.
5) You need to be careful that you're using the right size gas syringe for your experiment though - if the reaction is too vigorous, you can blow the plunger out of the end of the syringe.
52
practical - measure how surface area affected rate
marble chips ,hydrochloric acid, gas syringe, CO2 gas, electronic stopwatch, flask, powdered chalk
set the apparatus up
measure the volume of gas produced using a gas syringe , take readings at regular time intervals and record results
plot a graph of results
repeat experience with the sane volume and concentration of acid and same mass of marble chips but with the marble more crunched up
repeat w same mass of powdered chalk
53
using finer particles means the marble had a
larger surface area
54
how temperature affects reaction rate - practical
look at the reaction between thiosulfate and hydrochloric acid.
measure out fixed volumes of sodium thiosulfate and hydrochloric acid using a measuring cylinder
use a water-bath to gently heat both solutions to desired temperature before you mix them
mix solutions in a conical flask
place flask over a black cross on a piece of paper, watch black cross disappear thru the cloudy, yellow sulfur and time how long it takes to go
can be repeated at different temperatures, depth + volume should stay the same
55
56
57
faster rate of reactions are shown by…
steeper gradients
58
how to draw a tangent to find the gradient of a curve?
just the line that touches the curve and has the same gradient as the line at that point
59
rate of reaction depends on…
temperature
concentration
pressure
60
in order to react, particles must..
must collide with enough energy
61
the rate of a chemical reaction depends on
the collision frequency of reacting particles
the faster the reaction the more successful
the energy transferred
62
the minimum amount of energy that particles need to react is called…
the activation energy
63
how does increasing the temperature affect the rate of reaction
higher the temp, the faster the particles move
increases the energy of collisions since the particles are moving faster
more successful collisions for higher temperatures
64
how does increasing concentration or pressure increase rate of reaction
more concentrated = more particles of reactant in the same volume
this makes collision more likely so reaction rate increases
in a gas, increasing the pressure means particles are more crowded , so frequency of collisions increases
65
66
how does more surface area means a higher rate of reactions
particles around it will have more area to work on so the frequency will increase
this means that the rate of reaction is faster for the solids with a larger surface area to volume ratio
67
what does a catalyst do?
increases the rate of a reaction
68
catalysts work by…
decreasing the activation energy needed for a reaction to occur
they do this by providing an alternative reaction pathway that has a lower activation energy
as a result, more particles have at least the minimum amount of energy needed for a reaction
69
what do enzymes control
cell reactions
70
enzymes are …
biological catalyst
71
what does a biological catalyst do?
catalyse the chemical reactions in living cells
72
what are enzymes from yeast cells used for
fermentation , they catalyse the reaction that converts sugars into ethanol and carbon dioxide
73
what is an endothermic reaction
what is an exothermic reaction
endothermic - takes energy in from surroundings using heat, fall in temperature
exothermic - gives out energy to the surroundings using heat, rise in temperature
74
endothermic reactions on a graph
low flat, high rise , small fall, flat
75
exothermic reaction on a graph
high flat, small rise, large fall , flat
76
change in temperature of a reaction mixture as a reaction takes place practical
put a polystyrene cup into a beaker w cotton wool
add a known volume of your first reagent to the cup
measure initial temperature
add a measured mass/volume of a second reagent and stir
put a lid on the cup to reduce any energy lost by evapouration
record the max or minimum temperature
calculate temperature change
77
what is a displacement reaction
when a more reactive element displaces a less reactive element in a compound
(exothermic)
78
what is a neutralisation reaction
when an acid and a base react to form a salt and water
exothermic
79
precipitation reactions
when insoluble solids which can sometimes form when two solutions are mixed together
exothermic
80
bond breaking is what kind of process
endothermic
81
bond formation is what kind of process
exothermic
82
in endothermic reactions the energy used to break bonds is …
greater than the energy being released by forming them
83
in exothermic reactions the energy released by forming bonds is …
breather than the energy used to break them
84
how to calculate overall energy change ?
energy required to break bonds - energy released by forming bonds
85
a positive energy change means an _________ reaction
endothermic
86
a negitive energy change means an ________ reaction
exothermic reaction
87
is fossil fuel renewable
non renewable fuels ( finite resources ) they will run out one day
