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From Flashcardlet > Chemistry Unit 2 > Flashcards

Chemistry Unit 2 Flashcards

0
Q

What is the reaction for neutralisation?

A

Acid + base –> salt + water

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1
Q

What are the 2 main uses of precipitation reactions?

A

To remove poisonous ions from drinking water

Treating sewage

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2
Q

For the acid + metal reaction, what indicates the rate of reaction and what confirms the hydrogen?

A

Rate of reaction = rate at which bubbles of hydrogen are given off

Hydrogen confirmed by the burning splint test giving a squeaky pop

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3
Q

Describe how you would make insoluble salts

A

Use precipitation

Work out the positive and negative ion of the salt

Mix a nitrate of positive ion in solution with sodium and the negative ion in solution (this is because most nitrates and group 1 compounds are soluble)

You would then get a precipitate of the wanted salt (solid) and sodium nitrate solution in the flask

Then you filter the salt from the solution, wash it and dry it on filter paper

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4
Q

Describe how you make a soluble salt using an alkali

A

You can’t add an excess of alkali because you can’t tell whether the reaction has finished in this case

You add just the right amount of alkali to acid and order to neutralise the acid (you use an indicator to work out how much alkali is needed to neutralise the acid)

You repeat using exactly the same amounts of acid and alkali so that the salt isn’t contaminated by the indicator

Crystallise the salt

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5
Q

What is ammonium nitrate used for and why?

A

Very good fertiliser

It has nitrogen from 2 sources (ammonia and nitric acid) and plants need nitrogen to make proteins

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6
Q

Describe how you make a soluble salt using a metal or insoluble base

A

Pick the correct acid and metal / insoluble base to make the salt you need

Add the insoluble base or metal to the acid and the solid will dissolve in the acid as it reacts

When all acid has been neutralised, the excess solid won’t dissolve

Then filter out the excess solid to get the salt solution

To get pure, solid crystals of the salt, use crystallisation

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7
Q

What is an acid?

A

A substance with a pH below 7 that forms H+ ions in water

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8
Q

What is an alkali?

A

A base that dissolves in water (forms OH- ions in water)

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9
Q

Describe crystallisation

A

To get pure, solid crystals of the salt you use crystallisation

You evaporate some of the water to make the solution more concentrated and then leave the rest to evaporate very slowly

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10
Q

What are the 2 neutralisation reactions and the other similar reaction?

A

Acid + metal oxide –> salt + water

Acid + metal hydroxide –> salt + water

Similar reaction:

Acid + metal –> salt + hydrogen

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11
Q

What are the 2 ways of making soluble salts?

A

Using metal or insoluble base

Using an alkali

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12
Q

What salts do hydrochloric, sulphuric and nitric acids produce?

A

Hydrochloric –> chloride

Sulphuric –> sulphate

Nitric –> nitrate

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13
Q

What is a base?

A

A substance with a pH above 7

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14
Q

What happens when ammonia reacts with an acid?

A

Ammonia + hydrochloric acid –> ammonium chloride

Ammonia + sulphuric acid –> ammonium sulphate

Ammonia + nitric acid –> ammonium nitrate

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15
Q

What does diatomic mean?

A

An element that naturally has 2 covalently bonded atoms such as H^2

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16
Q

Describe electroplating

A

You can coat the surface of one metal with another metal

The negative electrode is the metal to be plated and the positive electrode is the metal that will plate it. The electrolyte also contains the ions if the playing metal

The ions that plate the metal come from the solution and the positive electrode keeps the solution topped up

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17
Q

Which substances made by electrolysis are diatomic?

A

Hydrogen at the cathode

Halides at the anode

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18
Q

Show how sodium chloride solution would break down in electrolysis

A

Hydrogen is less reactive so at the negative electrode, the H+ ions lose their charge
Because a halogen will form at the positive electrode if possible, the Cl- ions will lose their charge and become the halogen chlorine
When the electricity is turned off, the Na+ and OH- ions are left so they react to form sodium hydroxide

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19
Q

What are the 2 reasons for electroplating?

A

Decoration (plate a cheap metal with an expensive metal to make it look expensive)

Conduction (copper often plates metals for electronic circuits because it conducts electricity so well)

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20
Q

Why does the positive electrode have to be replaced?

A

When oxygen forms at the electrode, it reacts with the carbon of the electrode and forms carbon dioxide

This reaction eats away the carbon of the electrode

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21
Q

What are the 4 uses of electrolysis?

A

Extract a metal from an ore
Purify copper
Create substances from salt
Improve surface of a metal

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22
Q

What are the cathode and anode?

A

Anode is positive electrode

Cathode is negative electrode

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23
Q

What is brine?

A

Sodium chloride solution

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24
Q

How do you remember the difference between oxidation and reduction?

A

OIL RIG
Oxidation is loss (of electrons)
Reduction is gain (of electrons)

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25
Q

Why is electrolysis more complicated in aqueous solutions?

A

Because ions in the water are present as well as the ions in the compound

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26
Q

What is electrolysis?

A

The breakdown of a substance by passing electricity through it

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27
Q

Why isn’t an ionic solid an electrolyte?

A

The ions are not free to move so the current cannot pass through them

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28
Q

What are the rules about reactions at the positive electrode?

A

If hydroxide and halide ions are present, halogens will be produced and the hydroxide will stay as ions

If no halide is present, oxygen will be formed

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29
Q

Why is electrolysis of aluminium oxide so expensive and what is done to counter this?

A

It has to be heated up to 2000C for it to become molten

Cryolite (less common aluminium ore) is added and this brings the melting point down to 900C

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30
Q

What will form at the positive electrode if possible?

A

A halogen

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31
Q

What is an electrolyte?

A

An ionic substance that is either a liquid or dissolved in water

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32
Q

What are the rules about reactions at the negative electrode?

A

If metal ions and hydrogen ions are present, the metal ions will stay in solution and hydrogen will form if the metal is more reactive than hydrogen

This is because, the more reactive an element, the keener it is to stay as ions

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33
Q

What is a half equation?

A

A chemical equation that shows how an ion gains or loses electrons at an electrode
2H+ + 2e- –> H^2
2Cl- –> Cl^2 + 2e-

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34
Q

How do OH- ions oxidise? (Chemical equation)

A

4OH- –> O^2 + 2H^2O + 4e-

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35
Q

What 2 chemical properties are needed to use electrolysis in breaking down of a substance?

A

Substance is ionic

Ions are free to move

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36
Q

Why is electrolysis avoided if possible?

A

Expensive due to the cost of the electricity as a high current is needed

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37
Q

Why is electrolysis used for purifying copper?

A

Copper needs to be very pure for use as electrical wiring

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38
Q

What is Faraday’s law of electrolysis?

A

The higher the current used, the faster the substance is produced

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39
Q

What are the 2 reasons that the electrolysis of sodium chloride solution is useful in industry?

A

Chlorine is useful in bleach and plastics

Sodium hydroxide is a very strong alkali and used widely in the chemical industry

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40
Q

What is dynamic equilibrium?

A

When 2 conflicting sources make a reversible reaction not lose or gain any more products

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41
Q

What is an endothermic reaction?

A

A chemical reaction that absorbs heat from the surroundings

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42
Q

What is the industrial problem with reversible reactions?

A

If the reactants and products can’t escape the reaction area, the reaction would reach a state of equilibrium and the products would turn into the reactants just as much as the other way round

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43
Q

Is exothermic or endothermic rarer?

A

Endothermic reactions are rarer

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44
Q

What is a reversible reaction?

A

A reaction where the end products can react back into the original reactants

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45
Q

What is the main endothermic reaction?

A

When calcium carbonate thermally decomposes to form calcium oxide and carbon dioxide

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46
Q

Give 3 ways in which exothermic reactions are used

A

Heating
Generating electricity
Self-heating cans

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47
Q

What relates exothermic / endothermic and reversible reactions?

A

The forward reaction would be exothermic / endothermic and the backward reaction would be the opposite

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48
Q

Give 2 ways in which endothermic reactions are used

A

Ice packs for injuries

Self-cooling cans for drinks

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49
Q

What are the 3 main exothermic reactions?

A

Burning fuels

Neutralisation reactions

Oxidation reactions

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50
Q

How do we show a reaction is reversible in a chemical formula?

A

Double-headed arrow

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51
Q

What is an exothermic reaction?

A

A chemical reaction that transfers heat to the surroundings

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52
Q

Describe the experiment you use to see the effect of a catalyst on rate of reaction

A

You put hydrogen peroxide in a conical flask and put in a catalyst

Use the volume of gas given off (oxygen gas) to calculate the rate of reaction

Do this method for all the different catalysts to be tested

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53
Q

How do you measure rate of reaction using change in mass?

A

If a reaction produces a gas, you can measure the rate of reaction by looking at the change in mass (gas is lost)

You measure the change in mass by using a balance and looking at how fast the mass goes down

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54
Q

What are the 2 advantages of using catalysts in industrial reactions?

A

Increases rate of reaction so the plant doesn’t need to operate for as long saving money

Allows the reaction to work at lower temperatures and pressures

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55
Q

What is the biggest problem with catalysts?

A

They are very specific

Only one type of catalyst will catalyse a specific reaction

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56
Q

Describe the experiment you use to see the effect of temperature on rate of reaction

A

Let the 2 clear solutions of sodium thiosulphate and hydrochloric acid react in a comical flask and use the precipitation method to calculate the rate of reaction

Then use a water bath to heat the solutions up before mixing them and calculate the rate of reaction

The second reaction should be faster

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57
Q

How does surface area affect the rate of reaction?

A

If the surface area is larger, more of the reactant is exposed meaning the particles of the other reactant are more likely to collide with it

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58
Q

How do you measure the rate of reaction with the volume of gas given off?

A

You use a gas syringe to collect up the gas of the reaction

The more gas given off in a given time, the faster the reaction

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59
Q

Why is a catalytic converter needed?

A

The harmful gases of carbon monoxide and nitrogen oxides are changed to the much less harmful carbon dioxide and nitrogen

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60
Q

What are the 2 problems with the precipitation rate of reaction experiment?

A

Different people might not agree on the exact point that the mark disappears

Only works for reactions where the initial solution is clear

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61
Q

What is collision theory?

A

The theory that substances react when the particles of the reactants collide, break apart and then re-form to create new substances

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62
Q

Describe the experiment you use to see the effect of surface area on rate of reaction

A

You put marble chips and hydrochloric acid in conical flask and use the volume of gas given off method to calculate the rate of reaction

You then do the same but crunch up the chips more which gives a larger surface area

The second reaction should happen faster

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63
Q

How does concentration change the rate of reaction?

A

If the particles are more crowded (higher concentration) they are much more likely to collide so the reaction is faster

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64
Q

What are successful collisions?

A

Collisions that result in a chemical reaction

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65
Q

Describe the experiment you use to see the effect of concentration on rate of reaction

A

You use the change in mass method to calculate the rate of reaction of magnesium metal and dilute hydrochloric acid

You do the sane reaction with a higher concentration hydrochloric acid

The second reaction should have a higher rate

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66
Q

How do catalysts work?

A

The catalyst particles collide with the reactant particles and lower the activation energy by providing an alternative route for the reaction

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67
Q

What are the 4 factors that can change the speed of a reaction?

A

Temperature, concentration, surface area and pressure

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68
Q

Where are catalysts used?

A

They are used in industrial chemical reactions where there isn’t much time
They are used in catalytic converters

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69
Q

What is the Haber process?

A

Iron is used as a catalyst to produce ammonia from nitrogen gas and hydrogen gas

70
Q

What is activation energy?

A

The amount of energy that needs to be put in to trigger the reaction

71
Q

What is concentration?

A

It is the amount of molecules of the reactant dissolved in a given volume of water

72
Q

How does temperature affect the rate of reaction?

A

If there is a higher temperature, the particles will vibrate more giving them more energy
More energy means they move faster and are more likely to collide

73
Q

Give 2 ways in which we can measure the rate of a reaction

A

How fast the reactants are used up

How fast the products of the reaction are formed

74
Q

How do you measure rate of reaction with precipitation?

A

This is when the product of the reaction is a precipitate that clouds the solution

Observe a mark through the solution and measure how long it takes to disappear

The quicker the mark, the quicker the tst

75
Q

What is the advantage and disadvantage of the change in mass experiment?

A

Very accurate because the mass balance is accurate

But the gas is released straight into the room

76
Q

What is pressure?

A

How much gas has been squashed into a given area

They have more pressure making the particles closer together

77
Q

What is a catalyst?

A

A substance that massively increases the rate of a reaction without being used up or changed

78
Q

What are the 3 ways of measuring the rate of reaction?

A

Change in mass

Volume of gas given off

Precipitation

79
Q

What are the 3 disadvantages of using catalysts in industrial reactions?

A

They often need to be removed from the product and cleaned

Different reactions use different catalysts so they can be quite expensive

Catalysts can stop working because of impurities so you need to keep your reaction mixture very clean

80
Q

What is the advantage and disadvantage of the volume of gas given off experiment?

A

The volume of gas measured is very accurate

If the reaction is too violent, you can blow the plunger out of the end of the syringe

81
Q

How does pressure affect the rate of reaction?

A

If we squash more gas into a smaller area, the molecules will be closer together meaning they are more likely to collide

82
Q

What is thin layer chromatography?

A

A variant of paper chromatography that uses silica plates instead of filter paper as a stationary phase

83
Q

What do substances need to be so that mass spectrometry works?

A

They need to be ionised to be detected

84
Q

How does chromatography purify substances?

A

The substance that needs to be purified will be separated from other substances which makes it pure

85
Q

Describe the process of paper chromatography

A

A pencil line is drawn 1 cm above the base of the filter paper with a ruler
The different substances are spotted onto the line at different points
Reference substances are also spotted onto the line
The bottom of the filter paper is dipped in solvent
The substances travel up the filter paper with the solvent and stop at different points forming a chromatogram

86
Q

What are the 3 advantages of using machines for chemical analysis?

A

Can detect even the tiniest amounts of substances

Very fast and tests can be automated

Very accurate

87
Q

What is the retardation factor?

A

How much a substance favours the mobile phase or stationary phase
1 for mobile and 0 for stationary

88
Q

What does the height of a peak on the mass spectrum mean?

A

Each peak represents an ion

The higher the peak, the heavier the ion

89
Q

What is gas chromatography?

A

A form of chromatography that uses a carrier gas as a mobile phase and is very accurate

90
Q

Describe gas chromatography

A

The substances are heated until they become gases
The carrier gas brings the substances along a tube and they pass a sensor
The fact that they travel at different speeds means that they will go through the sensor at different times

91
Q

What is the stationary phase?

A

The part of the chromatography equipment that does not move and is usually solid

92
Q

What is chromatography?

A

A chemical process that separates mixtures of dissolved substances

93
Q

What is the advantage of using thin layer chromatography instead of paper chromatography?

A

Small quantities of the substances can be used

94
Q

What is a mass spectrometer?

A

An instrument that weighs molecules and tells us the molecular mass of substances

95
Q

Why do we use reference substances?

A

So that we can see if some of the unknown substances are actually the reference substances

96
Q

What is a mass spectrum?

A

The graph output of a mass spectrometer

97
Q

What is a locating agent?

A

A chemical that reacts with a substance to form a coloured compound

98
Q

What is the stationary phase in paper chromatography?

A

Filter paper

99
Q

What is the retention time?

A

The time a substance takes to reach the detector

100
Q

How do we know if an unknown substance and a reference substance are the same?

A

They will be level in height on the chromatogram

101
Q

What is chemical analysis?

A

Analysing substances to find out their chemical composition and structure

102
Q

What do we do to distinguish invisible spots?

A

Dip the filter paper in locating agent

103
Q

What is a chromatogram?

A

The filter paper in paper chromatography with the spots at different heights after the chromatography has taken place

104
Q

Why can’t some substances be detected by colour on the chromatogram?

A

They are colourless substances

105
Q

How do you calculate the retardation factor?

A

Distance between spot and pencil line / distance between top of mobile phase and pencil line

106
Q

How does chromatography find out which substances are present?

A

The substances are separated from each other meaning that they are pure so we can analyse which substances are present

107
Q

Give the 2 uses of chromatography

A

Chemical analysis that finds out what the substances present are
Synthesis (purifying substances)

108
Q

Which substances are used as carrier gases and why?

A

Argon and nitrogen

They are inert (don’t react)

109
Q

Why do some substances move across the mobile phase at different speeds than each other?

A

Some substances have an equilibrium position that favours the mobile phase more or less than others

110
Q

What is the mobile phase?

A

The part of the chromatography that pushes the substances across the stationary phase

111
Q

What is retention?

A

How much a substance holds back (favours the stationary phase)

112
Q

What is paper chromatography?

A

A type of chromatography where colours present in a substance travel up the paper at different rates

113
Q

What is the mobile phase in paper chromotography?

A

Solvent

114
Q

What is an empirical formula?

A

A formula that gives the simplest whole number ratio of atoms in a compound

115
Q

What are the 7 factors that affect the sustainability of chemical production?

A

Feedstocks (renewable feedstocks needed)
Atom economy (high percentage)
Waste (minimised)
Energy in and out
Social and economic benefits (as much as possible)
Environmental impact (must be low)
Health and safety (processes can’t put workers in danger)

116
Q

Describe how you calculate an empirical formula

A

Mass / relative atomic mass for each component

Divide each calculated number by the smallest of the 2 numbers calculated

Round to the nearest whole number
Put numbers into a ratio representing the components of the compound

The ratio should represent the number of atoms for the elements such as 1:2 being MnO^2

117
Q

What is percentage yield?

A

The amount of product received compared with the amount of product expected

118
Q

How could newly discovered chemicals be potentially hazardous?

A

We don’t know their long-term health effects yet so there are no hazard signs

119
Q

Why is empirical formula used?

A

It is a quick and accurate estimate of the molecular formula

However, it isn’t always right

120
Q

What is green chemistry?

A

The idea of making chemicals so that they endure the test of time and meet the needs of humans today and in the future

121
Q

How do we make sure chemical processes are safe?

A

Hazard symbols

Regular checks

122
Q

How do you calculate atom economy?

A

Molar mass of atoms in desired products / molar mass of atoms in reactants * 100 (percentage)

123
Q

What are the 3 reasons that a percentage yield is under 100%?

A

The reaction is reversible (reactants never completely converted to products)

Filtration (you always lose some of the substances)

Unexpected reactions (there can often be other reactions happening that use up the reactants)

124
Q

What is the formula for calculating percentage yield?

A

Actual yield / maximum theoretical yield * 100 (percentage)

125
Q

How do you calculate the maximum theoretical yield?

A

Add together the molar masses of all the atoms in the reactants
The molar mass of an atom of the element should be the relative atomic mass in grams

126
Q

Show how you would calculate the empirical formula of magnesium oxide? (The magnesium is 2g and the magnesium oxide is 3.25g)

A 
3.25 - 2 = 1.25
2 / 24 (magnesium relative AM) = 0.0833
1.25 / 16 (oxygen RAM) = 0.0781
0.0781 is smallest
0.0781 / 0.0781 = 1
0.0833 / 0.0781 = 1.0665
1.0665 is rounded to 1 (nearest whole number
So the ratio of the magnesium to the oxygen in the magnesium oxide is 1:1
This means the formula is MgO
127
Q

How do you make polymers in a way that they will be more flexible?

A

High temperature and high pressure to make it more flexible

128
Q

Why do nanoparticles have different properties to larger versions of the same material

A

The much larger surface area to volume ratio

129
Q

What is a smart material?

A

A material that changes one of its properties depending on its conditions

130
Q

Describe thermosoftening polymers

A

They don’t have cross-linking between chains so the chains are held together by weak intermolecular forces so they can slide over each other

Easy to melt

When it cools, the polymer hardens into a new shape

It can be melted and moulded again as many times as you like

131
Q

What are fullerenes?

A

Molecules of carbon shaped like hollow balls or closed tubes

They can be joined together to make nanotubes

132
Q

What is the most common natural nanoparticle?

A

Pollutants from burning fossil fuels

133
Q

What is a nanoparticle?

A

A particle from 1 to 100 nanometres

134
Q

What are the 7 uses of nanomaterials?

A

High surface area to volume ratio could help to make industrial catalysts

Can make sensors that detect only one type of molecule

Nanotubes can be used to make stronger and lighter building materials

Sun cream and deodorant made of nanoparticles don’t leave marks on the skin

Fullerenes are absorbed more easily by the body than other particles meaning that they could deliver drugs right into the cells they are needed

New lubricant coatings that massively reduce friction

Nanotubes conduct electricity so they could be used in tiny electric circuits

135
Q

What is a nanometre in comparison to a metre?

A

A billionth of a metre

136
Q

What is nitinol and what is it used for?

A

A shape memory alloy that returns to its original shape when heated

Used for braces because the heat of the mouth causes it to return to its original shape and gently pull the teeth in

137
Q

Describe thermosetting polymers

A

They have stronger intermolecular forces called cross links that hold the chains firmly together

Doesn’t soften when heated

Strong, hard and rigid

138
Q

What are the melting and boiling points of simple covalent substances like?

A

Usually gases or liquids at room temperature

139
Q

What are the 4 properties of metals?

A

Free electrons allow conduction of heat and electricity

They are strong because of the strong electrostatic attractions between the positive metal ions and negative electrons

The regular arrangement allows layers of atoms to slide over each other allowing metals to be bent and shaped

140
Q

What are simple covalent substances?

A

Where small covalently bonded compounds are held together by very weak intermolecular forces

141
Q

Describe metals

A

Metal atoms lose their outer electrons to their surroundings

If many metal atoms are together, the sea of delocalised electrons is enough to hold the atoms together in a regular structure

142
Q

Do simple covalent substances conduct electricity and why?

A

No

Because there are no freely moving charged particles

143
Q

Describe diamond

A

Each carbon atom forms four covalent bonds in a very rigid giant covalent structure

This makes diamond the hardest natural substance

144
Q

What are giant covalent substances?

A

Covalent structures where all atoms are bonded to each other by strong covalent bonds

145
Q

Describe graphite

A

Each carbon atom only forms 3 covalent bonds which creates layers that are free to slide over each other

Each carbon atom has one delocalised electron that is between the layers and holds them together (weak intermolecular forces)

Graphite is soft because the layers are free to slide over each other because of the weak intermolecular forces

Good conductor of electricity and heat because of the delocalised electrons

146
Q

What are the 3 properties of giant covalent structures?

A

High melting and boiling points (strong bonds)

Never conduct electricity (except for graphite)

147
Q

What happens when simple covalent substances melt or boil?

A

The intermolecular forces are broken and no harm comes to the covalent bonds

148
Q

How do you draw a dot and cross diagram for covalent bonding?

A

Draw a Venn diagram

Only draw the outer shells unless question asks otherwise

Put dots on one atom and crosses on the other

Put the required amount of the those dots and crosses in the overlap so that both atoms have a full outer shell

149
Q

Describe covalent bonding

A

Non-metals share electrons in their outer shells

This means that both atoms feel that they have a full outer shell

They are held together because the shared electrons are attracted by both nuclei

150
Q

Describe silicon dioxide

A

Sometimes called silica and it is what sand is made of

Each grain of sand is one giant structure of silicon and oxygen

151
Q

What can ionic bonds form between?

A

Only metals and non-metals

152
Q

How do you show ions by drawing their electronic structure?

A

Draw the electronic structures of the original atoms

Get rid of lost electrons and add gained electrons to the drawings

Put square brackets around each drawing and put the charge after the brackets of each ion

153
Q

What are the 4 main properties of ionic compounds?

A

High melting and boiling points due to the strong force of attraction

They dissolve easily in water

Melting ionic compounds or putting them into solution lets the ions freely move so they can conduct electricity

154
Q

How do you calculate the reaction for an ionic compound?

A

Look at the charge of the positive ion and look at the charge of the negative ion

Calculate how many of each ion is needed to get an overall charge of 0

The number of ions will be the subscripts in the ionic compound

155
Q

Describe ionic bonding

A

Atoms on the left side of the periodic table lose the electrons in their outer shell so that they have a full outer shell (they now have more protons than electrons so they have a +ve charge)

Atoms on the right side gain the electrons that the other atoms lost in order to get a full outer shell (they have a -ve charge because they now have more electrons than protons)

The opposite charges of the 2 ions hold them together as a compound

156
Q

Describe the structure of ironic compounds

A

Ionic compounds always have giant ionic lattices

The ions form a closely packed regular lattice arrangement

There are very strong electrostatic forces of attraction between oppositely charged ions in all directions

157
Q

What do you do if there is brackets in the formula unit?

A

Calculate the relative formula mass of the contents of the brackets and multiply that by the number after the bracket

158
Q

Why is the relative atomic mass of chlorine 35.5?

A

The 35.5 is an average

75% of chlorine is 35 and 25% is 37

159
Q

Why do isotopes chemically behave in the same way as each other?

A

Chemical reactions are determined by the number of electrons

160
Q

What is an element?

A

A substances where all atoms contain the same number of protons

161
Q

How do you calculate relative formula mass?

A

Add together the relative atomic masses of every atom in the compound

162
Q

How do you work out how much 1 mole is of a substance?

A

1 mole is the relative atomic mass or relative formula mass in grams

163
Q

What is the atomic number?

A

The number of protons in the element

164
Q

Show how would calculate the relative formula mass of water

A

In water, there is one oxygen and 2 hydrogens
16 + (2 * 1) = 18
The relative formula mass of water is 18

165
Q

What is the molar mass?

A

Another term for relative formula mass or relative atomic mass

166
Q

How do you calculate relative atomic mass?

A

Multiply mass number of isotope by its abundance for each isotope
Add them all together
Divide by 100

167
Q

What is the mass number?

A

The total number of protons and neutrons

168
Q

If we know the relative formula mass of water is 18, how much is 1 mole of water?

A

18g

169
Q

What is relative formula mass?

A

A way of calculating the mass of a compound compared to other compounds and elements

170
Q

What is relative atomic mass?

A

An average of the mass numbers of all isotopes of an element

171
Q

What is a formula unit?

A

When calculating relative formula mass, the formula unit is the compound we are calculating the relative formula mass of

172
Q

What are isotopes?

A

Variants of an element that have the same number of protons and electrons but a different number of neutrons

173
Q

Why are the physical properties of isotopes different?

A

The different numbers of neutrons will cause the masses of the different isotopes to be different

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