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Chemistry Flashcards

1
Q

What is the relative mass of protons,neutrons and electrons

A

protons=1
neutrons=1
electrons=0

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2
Q

What is the radius of an atom

A

0.1 nanometers

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3
Q

How do you measure an atoms radius

A

measure it from the nucleus to the electrons outer orbit

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4
Q

How does an atom become an ion

A

by losing or gaining electrons to make it balanced

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5
Q

In the periodic table what is another word for the boxes the atoms are arranged in

A

nuclear symbol

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6
Q

What does the atomic number of an element tell us

A

how many protons it has and electrons

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6
Q

what does the mass number tell us

A

how many protons and neutrons in an atom there is

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6
Q

T or F the number of protons and electrons in an atom are the same

A

True

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7
Q

What is an isotope

A

an atom with the same number of protons and electrons but a different number of neutrons

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8
Q

What does an element do if it’s isotope isn’t stable

A

It decays through radiation(alpha,gamma and beta)

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9
Q

What is radioactive decay

A

where an isotope emits radiation because it it unstable

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10
Q

How do electrons increase to another energy level

A

if they gain enough energy

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11
Q

How do electrons gain energy to increase to another energy level

A

from electromagnetic radiation

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12
Q

What happens after an electrons increases to another radiation and why does this happen

A

it will fall back down,it is not in a stable position because the energy runs out,it then re-emits electromagnetic radiation to it’s surroundings

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13
Q

What is the process of ionisation

A

where the outermost electrons gains so much energy that it is able to leave the atom completely,this leaves the atom with more protons than electrons which makes it a positive ion

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14
Q

What does ionising radiation mean

A

that it’s able to knock electrons of atoms

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15
Q

What happens when atoms mix with other substances

A

they lose the outermost electron and become a positive ion

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16
Q

What are the most reactive group of metals

A

1

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17
Q

what is the least reactive group of metals

A

transition metals

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18
Q

What are the measurments to make to when testing reactivity of metals

A

same mass and surface area and same type and concentration of acid

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19
Q

What will happen if you react metals with water instead of acid

A

It will form metal hydroxides and hydrogen

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20
Q

What is the idea of displacement reactions

A

that more reactive metals will replace less reactive ones

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21
Q

Write the reactivity series of metals from most reactive to least

A

Pottasium
Sodium
Lithium
Calcium
Magnesium
Carbon
Zinc
Iron
Hydrogen
Copper

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22
Q

What is the non metal in the reactivity series

A

carbon

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23
Q

What would the outcome be:magnesium sulfate+zinc

A

no reaction as magnesium sulfate is more reactive than zinc

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24
Q

What would the outcome be:Iron oxide+carbon

A

=Iron+carbon dioxide

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25
Q

what is the trend with date of discovery with the reactivity series

A

metals the less reactive metals were found the longest amount of time ago

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26
Q

Why is it that the less reactive metals in the reactivity series were found the longest amount of time ago

A

because ancient people used charcoal(pure carbon)in a fire/furnace which displaced and made the metals

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27
Q

What does an exothermic reaction do

A

it gives off heat to the surroundings like a fire

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28
Q

What does an endothermic reaction do

A

it takes in heat like a snowman

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29
Q

T or F most chemical reactions are exothermic

A

True

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30
Q

What happens to the activation energy on an exothermic reaction and why

A

it will increase as the reactants energy level is high

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31
Q

What physical process’s are seen in endothermic reactions

A

an ice cube melting

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32
Q

what can we measure exo and endo thermic reactions with

A

a themometer

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33
Q

Describe the process of energy through exothermic reactions

A

it starts with more energy and ends with less

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34
Q

Describe the process of energy through endothermic reactions

A

it starts with less energy and ends with more

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35
Q

Describe how freezing and condensation are exothemermic reactions

A

because bonds need to be made which gives out energy

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36
Q

Describe how melting and boiling and endothermic reactions

A

because bonds are broken which requires additional energy

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37
Q

When barium hydroxide and ammonium chloride react, the temperature of the mixture decreases. What kind of reaction is this?

A

This is an endothermic reaction

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38
Q

Why should a polysteyrene cup be used to measure energy change

A

because it insulates the surroundings from losing or gaining heat to it’s surroundings

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39
Q

If the energy change on an energy level diagram is negative, what does this tell you about the reaction?

A

It is exothermic

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40
Q

On a reaction profile, what does the height of the hump represent?

A

the activation energy

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41
Q

T or F thermal decomposition is an endothermic reaction

A

true

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42
Q

When calcium reacts with water, the temperature changes from 18°C to 39°C.What will the end solution be?

A

The solution at the end will be alkaline

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43
Q

If a reaction releases more energy when bonds are made than the amount of energy absorbed to break bonds in the reactants.What type of reaction is it?

A

An exothermic reaction

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44
Q

What does a reaction profile show

A

a graph that shows the energy of the reaction changing over time

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45
Q

What are the y-axis and the x-axis on the reaction profile

A

y-axis:the amount of energy the chemicals have got at any particular moment
x-axis:called the progress of reaction

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46
Q

On a reaction profile if the reactants were higher on the y-axis than the products,what reaction is it?

A

an exothermic reaction

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47
Q

What is the rule of recation profiles to tell if it is exothermic or endothermic

A

if the product has a higher amount of energy it is endo if the products have a smaller amount of energy than the reactants it is exo

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48
Q

What is the overall energy change on a reaction profile

A

the difference in energy between the reactant and the product

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49
Q

if the overall energy change is negative on a reaction profile what does it tell us

A

that it is exothermic

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50
Q

What is activation energy

A

the minimum amount of energy needed for a reaction to start

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51
Q

In reaction profiles why isn’t the line a straight line and not a curve

A

because the bonds need to be broken which requires energy

52
Q

On a reaction profile where is the activation energy

A

the activation energy is an invisible line from the bit with the least energy to the peak of the curved line

53
Q

What do catalysts do

A

they speed up a chemical reaction without it being changed

54
Q

How do catalysts do their job

A

they provide an alternative reaction route that has a lower activation energy

55
Q

How does a catalyst work on a reaction profile

A

it decreases the activation energy making the peak of the curb smaller

56
Q

are reversible reactions present in reaction profiles(reactants and products)

A

yes

57
Q

What is a reversible reaction on a reaction profile

A

where reactants can turn into products and vica verca

58
Q

What is the definition of rate of reaction

A

the speed at which reactants get turned into products

59
Q

What is the result of magnesium and acid

A

a gentle stream of hydrogen bubbles

60
Q

What are the 2 ways of measuring a rate of reaction

A

how fast the reactants are being used
how fast the products are being formed

61
Q

What are the 2 equations for rate of reaction

A

quantity of reactants used/time taken
quantity of products formed/time taken

62
Q

What is the reality of the rate of reaction

A

the answer for it is actually the mean amount of time it has taken

63
Q

If you measure the rate of reaction in moles how is it different

A

the time is in minutes not seconds

64
Q

During an experiment on the rate of reaction what is the best equipment to use to measure the change in mass

A

a top pan balance

65
Q

During an experiment on the rate of reaction what is the best equipment to use to measure the gas volume

A

if the gas is very soluble in water than a gas syringe if not than a inverted measuring cylinder or a burette

66
Q

what does the reversible reaction symbol mean

A

that reactants can form products and the products can reform by heating or cooling back into the reactants(vica versa)

67
Q

If a reversible reaction is endothermic in one direction what is it in the other direction

A

exothermic

68
Q

What is equilibrium

A

a state in which opposing forces or influences are balanced.

69
Q

What term is used to describe a chemical reaction in which the forward and reverse reaction rates are the same?

A

a dynamic equilibrium

70
Q

What is a chemical equilibrium

A

a state in which the rate of the forward reaction equals the rate of the backward reaction.

71
Q

What is produced in the backward reaction in this equilibrium, when the reaction goes from right to left: NH4Cl(s) ⇌ NH3(g) + HCl(g)?

A

The product of the backward reaction is NH4Cl(s).

72
Q

When a reversible reaction is at equilibrium,what is true

A

The concentration of products remains constant over time

73
Q

The equation for the Haber process is: N2 + 3H2 ⇌ 2NH3. What gases will be present at equilibrium?

A

At equlibrium, there will be a mixture of nitrogen, hydrogen and ammonia. Ammonia has been produced by the forwards reaction.

74
Q

One of the stages in sulfuric acid production is described by this equation: 2SO2(g) + O2(g) ⇌ 2SO3(g). What will happen to the yield of SO3 if the pressure is increased?

A

It will go up, because the equilibrium position moves in the direction which forms the fewest molecules of gas.

75
Q

If the forward reaction in a reversible reaction is endothermic, what will be the effect of decreasing the temperature?

A

It decreases the amount of product present at equilibrium

76
Q

What is the effect of decreasing the pressure on the following equilibrium 2NO(g) + O2(g) ⇌ 2NO2(g)?

A

more NO2 will be formed as the equilibrium will shift in the movement which has more gas molecules

77
Q

What effect on the equilibrium position is produced by adding a catalyst to a system in equilibrium?

A

it will have no effect as a catalyst speeds up the forwards and backwards direction of the reaction

78
Q

What does the mass no. tell us

A

how many protons and neutrons it has

79
Q

what does AR stand for and what does it mean

A

it is the relative atomic mass which means it is the average mass of all the isotopes of the element

80
Q

Explain why chlorine has a relative atomic mass of 35.5

A

the isotopes are 35 and 37 which added and divided by 2 equal 35.5

81
Q

What is MR and what is it

A

it is relative formula mass,you use it if you want to find all the isotopes in a compound

82
Q

How do you find the relative formula mass

A

add together the relative atomic masses of all the compounds in that molecular formula

83
Q

What would the relative formula mass of magnesium chloride be

A

24+35.5(x2)=95

84
Q

What is the % mass of sulfur in Sulfuric acid(H2SO4)

A

AR of sulfur X no. of sulfur/MR of compound
32 X 1/98 X100=32.7%

85
Q

What is ionic bonding

A

Ionic bonding occurs between metal and non-metals. The metal loses electrons to form a positive ion and the non-metal gains electrons to form a negative ion.

86
Q

What is covalent bonding and when does it occur

A

A chemical bond formed when electrons are shared between two atoms.It typically occurs between 2 non-metals

87
Q

Give an example of covalent bonding

A

if there were 2 hydrogen atoms both of them would need 1 more electron to be stable,to make them stable they form together

88
Q

What is metallic bonding

A

where the metal ion stays still and vibrate and delocalised electrons can move freely throughout it

89
Q

What is the metal with the highest melting point and what does it make it useful for

A

Tungsten(3339)it is used for filaments in a light bulb

90
Q

What are alloys used for

A

breaks up the regular structure of a metal atom

91
Q

How do you make an alloy

A

by inserting different sized atoms

92
Q

What are alloys

A

they are harder than original metals because the irregulatiry of the structure helps stops rows of atoms from slipping over each other

93
Q

What are the 2 allotropes of carbon

A

fullerenes and graphene

94
Q

What are allotropes

A

different structural forms of the same element in the same physical state

95
Q

What is graphite made up of and what is it’s structure

A

graphene,multiple repeating hexagons with each carbon being bonded to 3 others

96
Q

How can graphene conduct electrcity

A

because one of it’s atoms donates it to a pool of delocalised electrons

97
Q

What are fullerenes

A

shapes made out of grapite like tubes or spheres

98
Q

How are fullerenes spheres useful and why is this

A

for example with drugs they can use it to form a sphee to act like a cage to deliver it to certain parts of the body,industrial catalysts because of their high surface area:volume

99
Q

What are the fullerene tubes used for and why is this

A

nanotechnology,electronics,to strengthen other materials(tennis racket frames),this is because of their high length:diameter ratio

100
Q

What was the first fullerene made and what is it

A

the buckminster fullerene-a hollow sphere made of 60 carbon atoms
formula:C60

101
Q

what is nanotechnology used in

A

medicine,batteries,fashion and food

102
Q

How are ions formed

A

when atoms lose or gain electrons

103
Q

What is an ionic compound

A

it is made up of charged particles called ions

104
Q

T or F ionic bonds are really strong

A

true

105
Q

What is oxidation

A

the process of gaining oxygen

106
Q

What is reduction

A

the process of losing oxygen

107
Q

How are metal oxides form

A

as most metals are quite reactive they react with the oxygen which oxidises it

108
Q

T or F most metals are oxidised

A

true

109
Q

What are the exceptions to metals being oxidised

A

metals like gold as they are very unreactive

110
Q

What is the cheapest and easiest way to make pure metals and how does it work

A

to direct the metal oxides with carbon,the carbon takes the oxygen to form carbon dioxide to leave behind a pure metal

111
Q

When making pure metals why can’t you use the carbon method all the time

A

it only works on the metals that are less reactive than carbon

112
Q

Why is carbon placed in the reactivity series

A

when making pure metals the carbon method only works on the metals less reactive than carbon

113
Q

How do you make pure metals if the metal is more reactive than carbon

A

through a process called electrolysis but it is really expensive

114
Q

What is the most common iron ore

A

FE2O3

115
Q

What is the haber process

A

the industrial production of ammonia from nitrogen and hydrogen

116
Q

Why is the haber process one of the most important reactions in the world

A

because the ammonia it produces is used to make nitrogen based fertilisers which grows all the food we need

117
Q

For the haber process we need huge amounts of ammonia,how do we aqquire this

A

we would need lots of nitrogen and hydrogen
nitrogen is easy to get as it is 78% of our atmosphere
hydrogen is harder to get as we have to get it from hydrocarbons like methane

118
Q

What type of reaction is the haber process and what does that make it

A

exothermic as it produces heat so it would be reversible

119
Q

How does the haber process work

A

take the hydrogen and nitrogen and feed it in to the top left of the machine so they can mix together this happens at the reaction vessel,under the conditions in the reaction vessel they react to form ammonia but because it is a reversible reaction there will still be a lot of nitrogen and hydrogen

120
Q

What is in the haber process machine

A

where the nitrogen and hydrogen enter is called the reaction vessel,it is kept at 450 degrees and has 200atm,there is a tube in it which is where the iron catalyst is

121
Q

how do we separate the nitrogen and hydrogen from the ammonia

A

ammonia has a low boiling point,so in the machine it is passed into the condenser which will cool down the gaseous ammonia into liquid ammonia,and the hydrogen and nitrogen will stay as gasses as they have high boiling points

122
Q

In the haber process why does the temp need to be kept at 450 degrees

A

because it is an exothermic reaction we will need a lower temp to favour the forward reaction and to keep a higher % yield but it has to be 450 as for the rate of reaction the temp needs to be high and very high temp’s would be very expensive

123
Q

What are the 3 things to consider in the haber process

A

% of yield
rate of reaction
cost

124
Q

In the haber process why does the pressure need to be 200 atm

A

to achieve a high % of yield you need a high pressure a high amount of pressure would also achieve a high rate of reaction(makes particles collide more frequently)it has to be at 200 amp because maintaining a high pressure is expensive or can be very dangerous

125
Q

Fertilisers typically contain three essential elements. What are they?

A

nitrogen,phosphorus and pottasium

126
Q

Which essential elements are provided by the fertiliser potassium nitrate, KNO3?

A

Potassium nitrate contains potassium and nitrogen

127
Q

What useful compound is produced when phosphate rock is reacted with phosphoric acid?

A

Triple superphosphate (calcium phosphate) is made when phosphate rock is reacted with phosphoric acid.

128
Q

What is ammonia reacted with to produce nitric acid?

A

Ammonia, NH3, is oxidised to form nitric acid, HNO3

129
Q

Which two reactants are needed to make ammonium sulfate in the laboratory?

A

Ammonia + sulfuric acid → ammonium sulfate.

130
Q
A

Chemistry (14 decks)

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