reaction rates during the course of a chemical reaction, reactants are being converted into...
TRANSCRIPT
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.
