Reaction Rates During the course of a chemical reaction, reactants are being converted into products. Measurement of the rate of reaction involves measuring.

Reaction Rates• During the course of a chemical reaction, reactants

are being converted into products.

• Measurement of the rate of reaction involves measuring the ‘change in the amount’ of a reactant or product in a certain time.

• The rate of reaction changes as it progresses, being relatively fast at the start and slowing towards the end.

• What is being measured is the average rate over the time interval chosen.

• Reactions can be followed by measuring changes in concentration, mass and volume.

Where property = mass/volume/concentration

The above is used when there is no change in mass/volume/concentration measured, for

example during a colour change reaction.

Time (s) Volume (cm3)

0 0.00

5 7.00

10 10.50

15 12.00

20 12.75

25 13.00

30 13.00

Calculate the reaction rate;

• During the first 5 seconds • Between 10-15 seconds• Between 20-30 seconds• Of the whole reaction

(7-0/5-0 = 7/5 = 1.4cm3/s)

(12-10.5/15-10 = 1.5/5 = 0.3cm3/s)

(13-12.75/30-20 = 0.25/10 = 0.025cm3/s)

(13-0/30-0 = 13/30 = 0.43cm3/s)

Collision Theory

A chemical reaction can only occur if there is a successful collision between reactant molecules.

From S3 we know that we can speed up a chemical reaction by;

1. Decreasing particle size (increasing surface area)

2. Increasing concentration (of reactant)3. Increasing temperature4. Adding a catalyst

Collision Theory – Particle Size

• The smaller the particle size, the higher the surface area.

• The higher the surface area, the greater the number of collisions that can occur at any one time.

• The greater the number of collisions, the faster the reaction.

• Therefore the smaller the particle size, the faster the reaction rate.

Collision Theory – Concentration

• The higher the concentration, the higher the number of particles.

• The higher the number of particles, the greater the chance of collisions that can occur.

• The greater the number of collisions, the faster the reaction.

• Therefore the higher the concentration, the faster the reaction rate.

Collision Theory – Temperature

• The higher the temperature, the higher the energy the particles have.

• The higher the energy, the faster the particles move.

• The faster the particles move, the greater the chance that they can collide

• The greater the number of collisions, the faster the reaction.

• Therefore the higher the temperature, the faster the reaction rate.

Catalysts

• A catalyst speeds up a chemical reaction without getting used up or changed itself.

• Catalytic converters are used in exhaust systems to turn harmful gases into less harmful gases. Platinum, rhodium (expensive transition metals) are used as the catalyst used in catalytic converters.

https://www.youtube.com/watch?v=rmtFp-SV0tY

The atom is made up of a dense centre called the nucleus, which contains protons and neutrons

The electrons are very light and are found in a space around the nucleus called the electron shell.

Modern Day Model

of the atom

Particle Mass Charge Location

Proton 1 +ve(positive)

Neutron

1 0 (no charge)

Electron

zero(1/1850)

-ve(negative)

16

8

Important

• Atomic Number = No. of ____________

• No. of Protons = No. of ____________ (when the atom is neutral!)

• Mass Number = No. of __________ + No. of _________

• No. of Neutrons = Mass Number - ____________ __________

SymbolNo. Of

ProtonsNo. Of

NeutronsAtomic Number

Mass Number

No. Of Electrons

24

12 Mg12

80

35 Br45

40

19 K19 19 40

9 F 9 9 19

SymbolNo. Of

ProtonsNo. Of

NeutronsAtomic Number

Mass Number

No. Of Electrons

16

8 O

31

15 P

24

12

S

SymbolNo. Of Proton

s

No. Of Neutron

s

Atomic Number

Mass Number

No. Of Electrons

24

12 Mg 2+

80

35 Br -

40

19 K +

16

8 O 2-

What if the element isn’t neutral?

Isotopes Protons Electrons Neutrons

28

14 Si

25

14 Si

31

14 Si

63

29 Cu

65

29 Cu

Isotopes

Isotopes are atoms of the same element Isotopes are atoms of the same element (same number of protons) but have (same number of protons) but have different number of neutrons.different number of neutrons.

This means for isotopes,This means for isotopes, the atomic number the atomic number stays the same but the mass number stays the same but the mass number changes.changes.

Many elements exist as 2 or more isotopes.

The relative atomic mass (R.A.M.) of an

element is the average mass number for

a sample of that element.

R.A.M is related to isotopes.

The relative atomic mass of Copper (Cu) is 63.5The relative atomic mass of Copper (Cu) is 63.5

What does this tell you about the proportion of What does this tell you about the proportion of the two types of isotopes in a sample of the two types of isotopes in a sample of copper? copper?

Electron Arrangements Electrons are arranged in shells (or energy levels.)

Lithium has the electron arrangement 2,1 so there are two electrons in the electron shell closest to the nucleus, and one in the next shell:

LiX X

X

The 2,8,8,2 Rule

• For the first 20 elements (hydrogen to calcium) we follow the 2, 8, 8, 2 rule.

• A maximum of 2 electrons are allowed in the 1st electron shell, 8 electrons in the second, 8 electrons in the 3rd and 2 electrons in the 4th.

• Each electron shell must be full before the next one is started.

Coincidence? Maybe. Maybe Not?

The number of ______ ________ affect the way that the atom reacts.

In other words…

Elements with the same number of outer electrons (elements in the same group)

have similar chemical properties.

Important groups to remember;

• Group 1 – the alkali metals; all very reactive soft metals. (two examples are ________ and ________)

• Group 2 – alkaline earth metals; similar to group 1 metals but not as soft or reactive. (two examples are ________ and ________)

• Group 7 – the halogens; very reactive non-metals. (two examples are ________ and ________)

• Group 8 – the noble gases; very unreactive non-metals (two examples are ________ and ______)

• In-between groups 2/3 – transition metals. (two examples are ________ and ________)

Colour in all of the solid elements one colourColour in all of the solid elements one colour(easiest thing to do is leave them (easiest thing to do is leave them whitewhite!)!)

Colour in all of the liquids one colour Colour in all of the liquids one colour (Bromine and Mercury)(Bromine and Mercury)

Colour in all of the gases one colourColour in all of the gases one colour. (elements 1, 7, 8, 9, 17 and all of group 0)(elements 1, 7, 8, 9, 17 and all of group 0)

Remember to label Remember to label what each colour what each colour

represents.represents.

a) Carbonb) Magnesiumc) Potassiumd) Fluorinee) Oxygenf) Nitrogeng) Beryllium h) Aluminiumi) Neon j) Bromine

For each of the elements (right)

write down the following;

Name –

Symbol -

Atomic number –

Mass number -

Number of protons –

Number of electrons –

Number of neutrons –

Electron Arrangement –

Group number –

Metal or non metal –

Solid, liquid or gas -

Why do atoms bond?Why do atoms bond?

Noble gases have a complete outer electron shell.

This arrangement of electrons is very stable and therefore other elements want to be like the noble gases.

The number of electrons the element needs to lose or gain to be like the noble gases is called the valency. The atoms of other elements can collide together and combine to achieve the full outer electron shell.

The Covalent BondThe Covalent Bond

OX X

X

X

X

X

XX O XX

X

X

XX

XX

Two atoms get close enough Two atoms get close enough to to

each other to collide. each other to collide.

Oxygen with red Oxygen with red crosses – 2,6crosses – 2,6

Oxygen with Oxygen with purple crosses – purple crosses –

2,62,6

The Covalent BondThe Covalent Bond

OX X

X

X

X

X

XX O XX

X

X

X

X

XX

The two atoms are attracted The two atoms are attracted

to one another through the to one another through the positive positive nucleus nucleus

of one and of one and the negative electrons of the the negative electrons of the

other. other.

The Covalent BondThe Covalent Bond

X

X

O

X

X

XX

X

XX

O

X

X

X

X

X

XX

The two atoms combine and The two atoms combine and shareshare enough outer electrons for each enough outer electrons for each of them to become stable (full outer of them to become stable (full outer shell)shell)

Oxzygen with Oxzygen with red crosses – red crosses –

2,82,8

Oxygen with Oxygen with purple crosses – purple crosses –

2,82,8

A covalent bond is a shared pair of electrons

between non-metal atoms.

A covalent bond is held by the attraction of the positive nucleus and negative outer electrons of the different atoms.

Naming Covalent Compounds

If a compound name ends in ‘-ide’ then that compound only contains two elements – e.g. carbon nitride contains carbon and nitrogen only.

Sometimes prefixes are used in naming compounds –

e.g. silicon dioxide

Mono – oneDi – twoTri – three Tetra - four

Draw the following covalent elements and compounds

using both the lines and the overlapping electron shells (circles.)

You only have to draw the outermost shell electrons.

Hydrogen Chloride (HCl)Phosphorus Trichloride (PCl3)

Water (hydrogen oxide) (H2O)

Sulphur Fluoride (SF2)

Ammonia (nitrogen trihydride) (NH3)

Carbon Dioxide (CO2) *** tricky

1.Hydrogen Sulphide

2.Hydrogen Chloride

3.Phosphorus Oxide

4.Carbon Sulphide

5.Hydrogen Fluoride

6.Carbon Chloride

7.Silicon Oxide

8.Carbon Hydride

9.Nitrogen Hydride

10.Carbon Nitride

Shapes of MoleculesShapes of Molecules

Formula = CHFormula = CH44

Name =Name = CarbonCarbon Tetrahydride;Tetrahydride;

Structure is drawn likeStructure is drawn like

NH3 H22O HCl

Challenge

Your challenge is to;

a) Work out the chemical formula

b) Name the compound (use prefixes if necessary)

c) Draw the line drawing +d) Draw these molecules

using the overlapping circles methods

e) Identify the shape of the molecule

1.Selenium and Iodine

2.Hydrogen and Fluorine

3.Carbon and Chlorine

4.Carbon and Hydrogen

5.Nitrogen and Hydrogen

6.Phosphorus and Bromine

7.Carbon and Sulphur

8.Silicon and Oxygen

Properties of Covalent Molecules

Methane molecule (CH4)

This is a covalent molecule. Other examples include

water (H2O), oxygen (O2) and candle wax (C8H18).

Covalent molecules;

– have low melting and boiling points– can be solid, liquid or gas at room temperature. – never conduct electricity (in any state)

Covalent Network Substances

Some covalent substances do not have individual

molecules.

Diamond is an example of a covalent network structure. Sand (silicon dioxide) is another

example.

This is a diamond structure (carbon atoms only.)

Covalent networks;

• have extremely high melting and boiling points.

• are always solid at room temperature.• never conduct electricity

graphite is the exception to this rule as although it is a covalent network it will conduct electricity.

Properties of Covalent Network

• Although the covalent bonds within covalent molecules are strong, the force of attraction between the molecules are weak.

• These weak forces of attraction don’t require a lot of energy to break and therefore covalent molecules have low melting/boiling pts.

• All bonds in a covalent networks are very strong covalent bonds and it takes a lot of energy to break these bonds – i.e. very high melting/boiling points.

Type of covalent

substances

CovalentMolecular

CovalentNetwork

Melting/Boiling Pts

Type of bond broken

Strength of bonds broken

Typical Past Paper Questions - Bonding

Which line in the table shows the properties of a covalent molecular compound?

Which of the diagrams (left)

show the structure of a diatomic compound?

ABCD

Which diagram (left) shows

the structure of a covalent

network structure?

ABCD

When a __________ atom wants to become stable and bond with a non-metal atom, it gives away or loses electrons.

Metals lose electrons to get a full outer shell.

These ‘lost’ electrons don’t just disappear – instead;

Non metals gain electrons to get a full outer shell.

Ionic Bonding

ion ion

http://www.youtube.com/watch?v=QqjcCvzWwww

An ionic bond is between a metal and non metal. An ionic bond is held together via the attraction between the positive metal ion and the negative non metal ion.

• Ionic compounds don’t form molecules like covalent substances. They are arranged in large lattice structures.

• The ________ metals ions are attracted to the _______ non metals ions.

1. This attraction is very strong making an ionic lattice a strong stable substance – because of this ionic compounds are always solid at room temperature.

2. Ionic compound conduct electricity when molten (melted) and when in solution but NOT as a solid. This is because the ions are free to move.

3. Ionic compounds have high melting points and boiling points normally in the range; 400oC to 1400oC.

For each of the following elements;

1. Draw the electron arrangement of the atom.2. Draw the electron arrangement of the ion.3. Work out the charge of the ion. 4. Name the noble gas that the ion similar to.

a) Aluminium f) Oxygen b) Magnesium g) Chlorine c) Lithium h) Nitrogen d) Calcium i) Sulphur e) Potassium j) Bromine

Example; Beryllium

The Beryllium ion (charge ____) has the same electron arrangement as the noble gas _________________.

The ___________ ion (charge ____) has the same electron arrangement as the noble gas _________________.

Working out formulae of Ionic Compounds

Complex ions are ions which contain more than one element.

We can identify complex ions from their names as they end in ‘ite’ or ‘ate’. (the exceptions to this rule are hydroxide and ammonium)

Na

1 2

(SO42-)

1 2

Na2 (SO42-)

Work out the chemical formula for the following ionic compounds…

Remember the roman numerals indicate the valency of transition metals.

(Be careful some contain complex ions – see data booklet)

o Lithium Chloride Manganese (III) Chlorideo Aluminium Oxide Copper (III) Carbonateo Beryllium Bromide Rhodium (I) Oxideo Calcium Carbide Vanadium (II) Sulphateo Iron (II) Oxide Barium Carbonateo Copper (III) Iodide Cadmium (II) Hydroxideo Zinc (I) Sulphite Ammonium Phosphateo Calcium Hydroxide Ammonium Dichromateo Sodium Carbonate Zinc (II) Sulphideo Lithium Nitrate Hafnium (I)

Permanganateo Hydrogen Sulphate Aluminium Ethanoate

Sodium CarbonateCalcium SulphateBeryllium FluoridePalladium (II) BromideNickel (III) IodideTitanium (II) SulphiteCaesium SelenideBarium Chromate Potassium PhosphateSilver (I) OxideIron (III) Phosphide

Potassium iodide reacts with lead (II) nitrate to form a yellow solid and a clear solution. The products are thought to be lead (II) iodide andpotassium nitrate.

Word equation

Chemical equation

Molten iron is used to join steel railway lines together.

Molten iron is produced when aluminium reacts with iron (III) oxide. Another product is thought to be aluminium oxide.

Word Equation

Chemical Equation

Calcium carbonate reacts with hydrogen chloride to

form a calcium chloride, water and a gas. The gas

was tested and is turned limewater from colourless

to milky.

Write the chemical equation for the above reaction.

Balancing Equation Examples

Not only do we always have to have the same elements on both sides of a ‘reaction arrow’ but we also need to have the same amounts of them too.

In order for this to happen we need to balance the equation.

H = 2 H = 2

O = 2 O = 1

44

2

Balancing Equation Practice1. H2 + Cl2 HCl

2. Al + Cl2 AlCl33. C3H8 + O2 CO2 + H2O

4. Fe2O3 + CO Fe + CO2 ***

5. NaOH + H2SO4 Na2SO4 + H2O

6. NH3 + O2 NO + H2O ***

7. Mg(OH)2 + HCl MgCl2 + H2O ***

*** = tricky

Now try the sheet – do not write on it.

Formula MassThe formula mass (or gram formula mass - gfm) of

a substance is obtained by adding the relative

atomic masses of all of the elements in a compound

together.

In other words, the formula mass is the total mass of a compound.

The formula mass has NO units.

Worked Example 1

Calculate the formula mass of calcium chloride.

Formula;

Formula Mass;

Calcium =Chlorine =(Total) =

Worked Example 2

Calculate the formula mass of hydrogen sulphite.

Formula;

Formula Mass;

Hydrogen;Sulphur;Oxygen;(total)

Worked Example 3

Calculate the formula mass of magnesium nitrate.

Formula;

Formula Mass;

Magnesium =Nitrogen =Oxygen =(Total) =

Hydrogen oxide Calcium carbonate

Carbon dioxide Lithium phosphate

Nitrogen fluoride Hydrogen nitrate

Aluminium phosphide Ammonium sulphide

Magnesium bromide Gold (I) sulphate

Copper (II) iodide Silver (I) ethanoate

Zinc (III) oxide Potassium dichromate

Iron (II) chloride Nickel (III) chromate

Lead (II) nitride Tin (II) oxide

Mercury (I) bromide Platinum (II) sulphite

The Mole

One mole of a substance is the formula mass

but with the units grams.

For example;

One mole of calcium chloride = 111gOne mole of hydrogen sulphite =One mole of magnesium nitrate =

m = mass of substance

n = no. of moles

fm = formula mass

mass = mass =

no. of mole x formula massno. of mole x formula mass

m = n X fmm = n X fm

no of mole = no of mole =

mass / formula massmass / formula mass

n = m n = m

fmfm

formula mass = formula mass =

mass / no of molesmass / no of moles

fm = mfm = m

nn

Calculate the number of moles in Calculate the number of moles in 10.1g of potassium nitrate (KNO10.1g of potassium nitrate (KNO33))

0.75moles of a compound X weighs 14g.

Calculate the formula mass of the substance.

What mass of sodium carbonate What mass of sodium carbonate (Na(Na22COCO33) is present in 0.5 moles?) is present in 0.5 moles?

Questions

1. Calculate the mass of 3 moles of copper (I) bromide. CuBr

2. Calculate the mass of 4 moles of calcium nitrate. Ca(NO3)2

3. How many moles are there in 4.23g of magnesium carbonate? MgCO3

4. How many moles are there in 1kg of aluminium chloride? AlCl3

5. 0.75 moles of compound Z weigh 102.35g, calculate the formula mass.

6. 1.25 moles of compound Y weigh 69.40g, calculate the formula mass.

How many moles of each substance in;

A – 14g of Nitrogen gas (N2)B – 84.5g of Magnesium carbonateC – 400g of Copper (II) oxideD – 321g of Iron (III) hydroxide

What is the mass of;

A – 1 mole of aluminiumB – 2.5 Moles of Oxygen gas (O2)C – 0.5 moles of Lithium sulphateD – 0.1 moles of ethane (C2H6)

Calculation using Balanced Calculation using Balanced EquationEquation

Balanced equations can be used to calculate Balanced equations can be used to calculate masses masses

of substances involved in chemical reactions. of substances involved in chemical reactions.

When we write the balanced chemical equation, the When we write the balanced chemical equation, the

number in front of each formula represents the number in front of each formula represents the

number of number of moles moles of the substance.of the substance.

e.g. Ca + e.g. Ca + 22HNOHNO33 Ca (NO Ca (NO33))2 2 + H+ H22

What mass of calcium chlorideWhat mass of calcium chloride would be produced when would be produced when 10g of 10g of

calciumcalcium reacts fully with hydrogen chloride? reacts fully with hydrogen chloride?

Ca + Ca + 22HCl HCl CaCl CaCl22 + H + H22

CH4 + 2O2 CO2 + 2H2O

What mass of carbon dioxide is formed when 64g of methane

are burned completely in air?

Calculate the mass of iron that would be produced

from 2 moles of iron (lll) oxide.

Fe2O3 + 3H2 2Fe + 3H2O

C9H2O + 14 O2 9 CO2 + 10 H2O

Calculate the mass of water produced when 6.4g of

nonane (C9H2O) is burned.

The pH scale…The pH scale…

What does it really mean?

• RedRed - very acidic• OrangeOrange - slightly acidic• YellowYellow - very slightly acidic• GreenGreen - neutral• Green/BlueGreen/Blue – very slightly

alkaline• BlueBlue - slightly alkaline• PurplePurple - very alkaline

Oxide Acid formed

Other name of

acid

Acid formula

Ions in the acid

Carbon Dioxide

Carbonic Acid

Hydrogen Carbonat

e

Sulphur trioxide

Sulphuric Acid

Hydrogen Sulphate

Sulphur dioxide

Sulphurous Acid

Hydrogen Sulphite

Nitrogen Dioxide

Nitric Acid

Hydrochloric Acid

Hydrogen Chloride

Ethanoic Acid

Hydrogen Ethanoat

e

What conclusion can you come to..?

An acid is a solution which has a greater

___________________________________________ than pure water.

i.e.

Acids have an excess of hydrogen ions (H+ ions)

OxideOxide Name of Name of alkali formedalkali formed

Formula of Formula of alkalialkali

Ions in the Ions in the alkalialkali

Sodium Sodium OxideOxide

Sodium Sodium HydroxideHydroxide

Potassium Oxide

Calcium Oxide

Ammonia (NH3)

Ammonium Hydroxide

What conclusion can you come to..?

An alkali is a solution which has a greater

______________________________than pure water.

i.e.

Alkalis have an excess of hydroxide ions (OH- ions)

Neutral Substances

• Water has equal amounts of H+ and OH- ions so the overall pH is neutral (pH 7)

• During neutralisation reactions the H+ ion (from the acid) and the OH- ion (from the alkali) react and produce water.

• The H+ and OH- ions being able to move is the reason why water conducts electricity.

• All solutions contain both H+ and OH- ions.

• Acids have more H+ than OH- ions

• Alkalis have more OH- than H+ ions

• Neutral substances have equal amounts of H+ and OH- ions

Diluting Acids or Alkalis

Diluting an acid or alkali is similar to what happens with diluting juice.

As an acid is diluted it becomes ‘weaker’ as there are less H+ ions. As a result the pH increases towards pH 7 until it eventually becomes neutral.

As an alkali is diluted it becomes ‘weaker’ as there are less OH- ions. This means the pH decreases towards pH 7 (neutral)

Acids can be neutralised using bases.

Worked Example

Neutralisation Reactions

Sodium Hydroxide + Hydrochloric Acid Sodium Chloride + Water

ACID + Metal Hydroxide SALT + WATER

BasesBases

Bases are another word for alkalis.

Examples of bases are;– metal hydroxides, – metal oxides and – metal carbonates.

Bases neutralise acids to form water.

Salts

Salts are _______ _______ compounds (contain a positive and negative charge).

We can name the salt produced by looking at

the acid and base that have been used.

The first part of the salt’s name comes from the base used;

e.g. Sodium Hydroxide gives – sodium ……. Calcium Oxide gives – calcium …….

Ammonia gives – ammonium…….

The second part of the name comes from the type of acid used during the neutralisation;

Hydrochloric acid produces .......... chloride salts Sulphuric acid produces ................. sulphate

salts Nitric acid produces ..................... nitrate saltsEthanoic acid produces ……………… ethanoate

salts

1. Complete the names of the salts produced;

a) Calcium Hydroxide + Hydrochloric Acidb) Sodium oxide + Nitric Acidc) Potassium carbonate + Sulphuric Acid

2. Which acid has been used to make calcium sulphate?

3. Write the word equation for magnesium hydroxide

reacting with an acid of your choice.

Metal Oxide + Acid reaction

Example (from your experiment)

Word Equation

Chemical Equation (balance if necessary)

ACID + METAL OXIDE SALT + WATERACID + METAL OXIDE SALT + WATER

1. Add 10cm3 of acid and 10cm3 of water to a 100cm3 beaker.

2. Heat the acid until ALMOST boiling using a slightly blue flame.

3. When the acid is hot enough, use a spatula to add small amounts of copper(II) oxide (1g in total) to the beaker.

4. Stir the mixture gently for up

to half a minute after each addition.

5. When all the copper(II) oxide has been added, continue to heat gently for 1 to 2min to ensure reaction is finished.

6. Allow the beaker to cool while you set up the filtration.

Metal Carbonate + Acid reactions

Calcium carbonate (limestone) is often used for building materials.

Metal carbonates react with acid, so acid rain can damage limestone buildings.

ACID + METAL CARBONATE SALT + WATER + CARBON ACID + METAL CARBONATE SALT + WATER + CARBON DIOXIDEDIOXIDE

Ionic FormulaIonic Formula

Writing ionic formula is simply writing the chemical formula of a compound but showing the charges of the ions.

Metals form positive/negative ionsNon metals form positive/negative ions.

Chemical Formula – NaOH

Ionic Formula – Na+ OH-

Spectator IonsSpectator Ions

When acids and alkalis are added to water, they dissociate to form ions. Some of these ions react, and some do not. The ions that don’t react are called spectator ions.

Ionic equations make it easier to identify spectator ions. Rather than write the chemical formula of reactants and products, we can write the ions present in aqueous solution:

Sodium Hydroxide + Hydrochloric Acid Worked Sodium Hydroxide + Hydrochloric Acid Worked ExampleExample

Word Equation;

Formula Equation (with state symbols);

Ionic Equation (with state symbols);

Spectator ions appear on reactant and product sides of the reaction and remain unchanged, so we can cross them

out.

Rewrite equation without (omitting) spectator ions

Calculate the mass, in grams, of sulphuric acid (H2SO4) present in 500cm3 of a 5 mol/l solution

Step 1: Write the formula:

(C x V x P)acid = (C x V x P)alkali

C = Concentration of acid or alkali V = Volume of acid or alkali – Always make sure

the units of volume are the same on each side!!P = Number of H+ (for acid) Number of OH- (for alkali)

Titration CalculationTitration Calculation

Step 2Step 2: :

Find out the number of HFind out the number of H++ in the formula of in the formula of

acid. (e.g. HCl= acid. (e.g. HCl= 1 1 , H, H22SOSO44= = 2) 2) OROR

Find out the number of OHFind out the number of OH-- in the formula in the formula

of alkali. (e.g. NaOH= of alkali. (e.g. NaOH= 11, Mg(OH), Mg(OH)22= = 22) )

Step 3:Step 3: Put all of the known values into Put all of the known values into thethe

equation shown above.equation shown above.

Step 4:Step 4: Complete the calculation.Complete the calculation.

Examples of PowerExamples of Power

Work out the powers of either the H+ (acids) or OH- (alkalis) in the following;

• NaOH• Ca(OH)2

• H3PO4

• HCl• H2SO4

• Al(OH)3

• H5S2

Worked Example

In a titration, 10 cm3 of 2 mol/l sodium hydroxide (NaOH)

solution was neutralised by 25cm3 of dilute hydrochloric

acid (HCl).

Calculate the concentration of the acid in mol/l.

(C x V x P)acid = (C x V x P)alkali

In a titration, 25 cm3 of 2 mol/l sodium hydroxide (NaOH) solution was neutralised by 28.7cm3 of sulphuric acid

(H2SO4).

Calculate the concentration of the acid in mol/l.

In a titration, 20 cm3 of potassium hydroxide (KOH) solution was neutralised by 42.6cm3 of 0.5 mol/l

hyrdochloric acid (HCl).

Calculate the concentration of the base in mol/l.

In a titration, 2 mol/l sodium hydroxide (NaOH) solution was neutralised by 22cm3 of 0.1mol/l sulphuric acid

(H2SO4).

Calculate the volume of the base in cm3 that was neutralised.

In a titration, 0.05 mol/l potassium hydroxide (KOH) solution was neutralised by 17.1cm3 of 0.25mol/l phosphic

acid (H3PO4).

Calculate the volume of the base in cm3 that was neutralised.