C3 Revision Notes - Sets 1&2 only.pdf

7/25/2019 C3 Revision Notes - Sets 1&2 only.pdf

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MENDELEEV:

Arranged by atomic mass

Similar properties

Left gaps for elements yet

to be discovered

NEWLANDS:

Built on Daltons Law of

Octaves ( every 8

th

elementhad similar properties)

Arranged by atomic mass

Two elements in same box

Early Periodic Table

PeriodicTable


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Modern Periodic TablePeriodic

Table

Metals/Non-metals

Arranged by proton

number Groupsnumber of

electrons on outer

shell

Periodsnumber ofshells


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Group 1Alkali Metals

PeriodicTable

Group 1 metals1+ ion

Li, Na, Kless dense than water

Reaction with water --> make H2

Alkali metals.metal hydroxide

Universal indicatorpurple Down grouplower mpt/bpt

Reactivity INCREASES down the group Larger atom

Outer electron further away from +ve nucleus

EASIER to lose due to SHIELDING effect of

other electrons

Less electrostatic force

Stored in oil,

as reacts with

oxygen in air


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Group 7Halogens

PeriodicTable

Group 7 non-metals1- ion

Coloured vapours

Diatomic molecules

Down the grouphigher mpt/bpt

Forms ionic compounds with Grp1

Reactivity DECREASES down the group

Larger atom

Outer shell further away from +venucleus

HARDER to gain an electron due to

SHIELDING effect of other electrons

Less electrostatic force to attract

electron

HALOGEN

DISPLACEMENT

A more reactivehalogen will

displace a less

reactive one from a

compound


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Transition MetalsPeriodic

Table

Compared with Group 1

Higher mpt

Higher density

Stronger/harder

Much less reactive

Used for catalysts

Form coloured compoundsIons with different charges

Similar properties because they fill

an inner 3rdshell ( 3d shell). This

can hold 18 electrons, once 2

electrons fill the 4thenergy level.

Usually have same number of

electrons on outer shell


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Water Cycle

Water

Water

evaporates due

to Suns thermal

energy. Condenses to

form clouds

Precipitation (

rain/snow/sleet)

occurs.

Ionic compounds are soluble, butcovalent ones are not.


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Hard WaterWater

Contains Mg2+ and Ca2+ ions, dissolvedwhen water passes through rocks

+ve

- Ca for

bones/teeth

-ve

- Kettles furrow upless efficient

Soft watereasy lather

Hard waterless lather

SCUM

When hard waterreacts with soap.

SCALEWhen hard water

is heated.

SCALE is basically limescale which is Calcium

Carbonate which is a solid ppt and forms on

metal appliances reducing efficiency.


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Removing Hard WaterWater

Add Sodium CarbonatePrecipitates out the Ca and

Mg ions to form insoluble

carbonates

Use

washing

soda

IonExchange

(water

softener)

Filled with resin.

Contain Sodium/Hydrogen Ions

As the water is passed through

the resin, the Na/H ions are

EXCHANGED with the Ca/Mg

ions.

Needs to be topped up with Na

ions so NaCl is poured in to

replenish.


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Water TreatmentWater

Distillation =

PURE WATER

Made safe to drink by removingsolids and micro-organisms

Carbonreduces Cl levels

Ion exchange resin

Silverdiscourage bacterial

growth on filter

Water sourceFilter solids

Sedimentation of small particles using

Aluminium sulphate

Chlorineused to disinfect

Filter of fine sand


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PeriodicTable

Water

Acids &Alkalis

Energy

Analysis

C3


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Strong/Weak Acids/AlkalisAcids

&Alkalis

TESTING whether strong or weakuse Universal Indicator

STRONG ACIDS fully

dissociate into their ionsHCl H+ + Cl-

WEAK ACIDS partially

dissociate into their ionsCH3COOHH+ + CH3COO-

Same for alkalis, just OH- ions


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TitrationAcids

&Alkalis

Used to determine accurately how much alkali is needed to

react completely with a known volume of acid ( or vice-versa)

Phenolphthalein STRONG

ALKALI and WEAK ACID

Methyl Orange STRONG ACID

and WEAK Alkali

NEUTRALpH7

Known

volume

and conc

Unknown

volume

END POINTAcid-base

reaction is

complete


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Energy from fuelsAcids

&Alkalis

Energy

Calorimeter

Think

HSW!

Bomb

calorimeter

4.2J raises

temp of 1 g

of water by

1 degree

Food high in carbs and fats have

lots of energy!! more than

body needs obesity

A + BCIf 0.1 mole of reactants. Total mass of A and B is

100g.

Temp start is 19.6, temp max is 26.1

Work out diff.6.5

(Dont need to learn this, you would get this)

So for 0.1 moles = 2730J

For 1 mole 2730 x 10 27300J (27.3kJ)

..exothermic reaction ( as temp rise) = -27.3kJ/mol

Energy change = mass x 4.2 x temp change


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Energy changesAcids

&Alkalis

Energy

Reaction = bond breaking ( endo) and bond making ( exo)

EXOTHERMIC

Energy required to break

bonds in less than energy

released when new bonds

are formed

ENDOTHERMIC

Energy required to break

bonds in greater than

energy released when new

bonds are formed

CATALYST.

Lowers activation

energy

H = - ve

H = + ve


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Bond energiesAcids

&Alkalis

Energy

CH4(g)+ 2O2(g) 2H2O(l)+ CO2(g)

Identify the bonds..stick diagrams!

Bond Bond energy

kJ/mol

H-H 436

Cl-Cl 242

H-Cl 431

O-H 464

C-C 347

C-O 335

O=O 498

H = bond breaking + (- bond making)

Add up on the bonds in the reactants.

This is bond energy needed to break the bonds

Add up on the bonds in the products.

This is bond energy needed to make new bonds.

REMEMBER making new bonds is an exothermic

reactionso it is always a ve number


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Positive Ions

metal flame test colour

barium apple greencalcium brick red

potassium lilac

lithium bright red

sodium orange

Acids&

Alkalis

EnergyAnalysis

FLAME TESTS

Add

Sodium

Hydroxide

Cu 2+

Fe 3+

Fe 2+

Add NaOH, gently warm.

Ammonium gas turn red litmus

paper blue


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Negative IonsAcids

&Alkalis

EnergyAnalysis

Carbonatesadd acid

bubblesif they

turn limewater cloudy

Copper CarbonateCopper Oxide

Zinc CarbonateCopper Oxide

Halides Add nitric

acid and silver nitrate

Cl Br I

White Cream Yellow

SULPHATES

( add HCl to removes

any carbonate ions)

Add Barium Chloride

white ppt

NITRATES

Test for ammonia first negative resultAdd ALUMINIUM ( this reduces the

nitrate ion to Ammonium ions)

Test again for ammonia gas positive

result


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Titration Calculations

2NaOH + H2SO4Na2SO4+ 2H2O

Write what you know from the question.

V = 30cm3 Conc = ? V = 20cm3 Conc = 0.5

1. Convert vol into

dm3 by dividing

by 1000.

2. Calculate moles

of substance of

known vol and

conc

Moles = Concentration Volume

3. Look at the

equation for the

ratio. Here, it is 2:1

So we calculate

moles of acid here

and then multiply

this by 2

4. Now rearrange the formula

to allow you to work out the

unknown

If they want you to work

out the g/mol

All you do is multiply the

RFM ( they give you

this!) by the

concentration you

calculated

Analysis


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What is ammonia?

It is made industrially by reacting

nitrogen with hydrogen in the Haber

process. It is a reversible reaction,

so it never goes to completion.

hydrogennitrogen + ammonia

N2(g) 3H2(g) 2NH3(g)+

Ammoniais an important compound

in the manufacture of fertilizer and

other chemicals such as cleaningfluids and floor waxes.

Why is this a problem for companies

making ammonia?


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What is yield?The amount of product made in a reaction is called the

yieldand is usually expressed as a percentage.

ammon

iayield(%)

pressure (atm)

The yield of ammonia produced by the Haber process

depends on the temperatureand pressureof the reaction.


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What is the Haber compromise?

In practice, though, these

conditions are not used. Why?

The highest yield of ammonia

is theoretically produced by

using a low temperature anda high pressure.

A compromise is reached to make an acceptable yield in

a reasonable timeframe while keeping costs down.

Lowering the temperature slows down the rate of reaction.

This means it takes longer for ammonia to be produced.

Increasing the pressure means stronger, more expensive

equipment is needed. This increases the cost of producingthe ammonia.


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The Haber compromiseTo produce a high yield of ammonia, but with a fast rate

of reaction and without the need for overly expensive

equipment, the Haber process is carried out at 450Cand 200 atmospheres.

The most important factor in

deciding what conditions to use istherefore not yield, but total cost.

raw materials

equipment

energy

wages

What costs are involved in

the industrial production of

ammonia?


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Maximizing productivityWhat else can be done to maximise productivity in the

manufacture of ammonia?

An iron catalyst is used to increase the rate of

reaction. It speeds up both the forward and backward

reaction, so the position of equilibrium is not affected.

The ammonia is cooled, liquefied and then removed

as it is produced. This causes the equilibrium to shift to

the right to produce more ammonia.

Unreacted nitrogen and hydrogen are recycled andgiven another chance to react.


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What is dynamic equilibrium?In some reversible reactions, the forward and backward

reactions largely occur in the same conditions and at the

same rate.

These reactions are said to be in dynamicequilibrium

there is no overallchange in the amount of products and

reactants, even though the reactions are ongoing.

Dynamic equilibrium can only take place in a closed system,

otherwise the products would escape.

reactant A

+

productreactant B


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Setting dynamic equilibriumThe position of dynamic

equilibrium is not always at a

half-way point, i.e. when there areequal amounts of products and

reactants. It may be at a position

where there are mainly reactants

with a little product, or vice versa.

The position of equilibrium is influenced by two main factors:

temperature

concentration (or pressure for reactions involving gases)

Adding a catalyst speeds upthe time it takes to reach

equilibrium, but does not change the positionof equilibrium.


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Opposing changeWhenever a change is made to a reversible reaction in

dynamic equilibrium, the equilibrium will shift to try and

oppose the change.

Increasing the temperature shifts the

equilibrium in the direction that takes in heat.

Increasing the concentration of a substance

shifts the equilibrium in the direction that

produces less of that substance.Increasing the pressure shifts the equilibrium

in the direction that produces less gas.

Temperature

Concentration

Pressure

Condition Effect


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Exothermic and endothermic reactionsAll reactions are exothermic(give out heat) in one direction

and endothermic(take in heat) in the other.

If the temperature is increased:

If the temperature is decreased:

equilibrium shifts to decreasethe temperature

equilibrium shifts in the endothermicdirection

equilibrium shifts to increasethe temperature

equilibrium shifts in the exothermicdirection


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Concentration and equilibriumChanging the concentration of a substance affects the

equilibrium of reversible reactions involving solutions.

increasingthe

concentration of

substance A

equilibrium shifts to

decreasethe amount of

substance A

=

decreasingthe

concentration ofsubstance A

equilibrium shifts to

increasethe amount ofsubstance A=


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Pressure and equilibriumChanging the pressure has an effect on the equilibrium of

reversible reactions involving gases.

If the pressure is increased:

equilibrium shifts to decreasethe pressure

equilibrium shifts in the direction of fewest

molecules

If the pressure is decreased:

equilibrium shifts to increasethe pressure

equilibrium shifts in the direction of most

molecules


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Alcohols

What Are Alcohols?

Alcohols are organic chemical compounds which forma homologous series.

They are compounds in which one or more hydrogenatoms in an alkane (saturated hydrocarbon) arereplaced by hydroxyl (OH) groups.

The hydroxyl group (OH) is the part of the moleculethat is responsible for the characteristic reactions andchemical properties of the alcohol. This is otherwiseknown as the 'functional group'


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Ethanol

Ethanol is an alcohol.

Ethanol can be represented in a number ofdifferent forms:

C2H5OH CH3CH2OH


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Facts about Ethanol

Ethanol can:

Dissolve in water to form a neutral solution.

React with sodium to from hydrogen.

Burn in air. Be used as fuels and solvents, and is the main

alcohol in alcoholic drinks.

Ethanol can be oxidised to ethanoic acid (bychemical oxidising agents or microbial action).


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So what does Ethanol look like?

The molecular structure of ethanol looks like

this:

The OH part of Ethanol is

sometimes referred to as

the functional group


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Methanol

Methanol is another alcohol, which as we

know, is also a member of the homologous

series.

Methanol can be represented as a formula:

CH3

OH


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Methanol

The molecular structure of methanol look like

this:

The OH part of methanol is sometimes

referred to as the functional group!
http://localhost/var/www/apps/conversion/tmp/scratch_3//upload.wikimedia.org/wikipedia/commons/f/f1/Methanol_Lewis.svg


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Facts about Methanol

Methanol can:

Dissolve in water to form a neutral solution.

React with sodium to from hydrogen.

Burn in air.

Be used as fuels and solvents, and is the main

alcohol in alcoholic drinks.


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Carboxylic acid

A carboxylic acid is an organic acid that

contains one or more carboxyl groups. They

usually have higher boiling points than water

and are usually quite weak acids. These longerchain acids tend to be rather soluble in less-

polar solvents such as ethers and alcohols.


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Ethanoic Acid

Ethanoic acid can be found in your kitchen,any ideas? Yes, its vinegar! Ethanoic acid is

one of the simplest carboxylic acids.

The COOH part of ethanoic acid is sometimesreferred to as the functional group


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Facts about Carboxylic acids

Carboxylic acids:

Dissolve in water to produce acidic solutions.

React with carbonates to produce carbon dioxide.

React with alcohols in the presence of an acidcatalyst to produce esters.

Do not ionise completely when dissolved in waterand so are weak acids.

Aqueous solutions of weak acids have a higherpH value than aqueous solutions of stronger acidswith the same concentration.


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Esters

Esters are chemical compounds made by

condensing acids with alcohols. Esters with

low molecular weight are commonly used as

fragrances and found in essential oils andpheromones.


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Making an Ester

Ethyl ethanoate is synthesized in industry mainly via the

classic Fischer esterification reaction of an ethanol (alcohol)

and a ethanoic acid (carboxylic acid). This mixture converts to

the ester in about 65% yield at room temperature:

CH3CH2OH + CH3COOHCH3COOCH2CH3+ H2O

The reaction can be accelerated by acid catalysis and the

equilibrium can be shifted to the right by removal of water.


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What do esters look like?

-Ethyl ethanoate-

Ethyl ethanoate is the organic compound with the

formula CH3COOCH2CH3. This colourless liquid has a

characteristic sweet smell and is used in glues, nail

polish removers, decaffeinating tea and coffee, andcigarettes.

The COO part of ethyl ethanoate is

C3 Revision Notes - Sets 1&2 only.pdf

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