Acids and Bases 2014 GBL

Year 11 100 Science
4 External Credits
AS90944
Ms Gibellini

Aspects of acids and bases will be selected from:
 Atomic structure
 electron arrangement of atoms and monatomic ions of the first 20 elements (a periodic
table will be provided)
 ionic bonding
 names and formulae of ionic compounds using a given table of ions.
 Properties
 acids release hydrogen ions in water
 reactions (of acids with bases) to form salts.
 pH and effects on indicators.
 Rates of reaction and particle theory.
 Uses
 neutralisation
 carbon dioxide formation
 salt formation.
 Acids and bases are restricted to HCl, H2SO4, HNO3, metal oxides, hydroxides, carbonates and
hydrogen carbonates. Other acids may be included in examination questions. The names and
formulae of any such acids will be given in the question.

 Describe the structure of an atom
 Discuss the key differences between the three
sub-atomic particles

 All matter is made up of atoms
 Chemistry involves the rearrangement of
atoms or groups of atoms
 Recall the structure of an atom

 http://www.youtube.com/watch?v=pV822Hfq
T44&feature=fvwrel

 Atoms are made up of the following sub
atomic particles:
 Electrons
 negative charge
 outside nucleus, in shells
 constant motion
 very very small (1/2000 of a proton)
 Neutron
 No charge, neutral
 Inside nucleus
 Same size as proton
 Proton
 Positively charged
 Inside nucleus

 A neutron walks into a restaurant and orders
a couple of cokes.
 As she is about to leave, she asks the waiter
how much she owes.
 The waiter replies, "For you, No Charge!!!"

 Atoms have an overall neutral charge,
therefore:
 Number of protons = Number of electrons

 Complete worksheets provided
 Compete Scipad page 10: Atoms
 Describe the atomic structure of a lithium
atom
 Explain how the particles within an atom
contribute to its overall mass.

 Describe the atomic structure of a lithium
atom
 Explain how the particles within an atom
contribute to its overall mass.
Overall mass of an atom is made up of protons
and neutrons, as the mass of electrons is
negligible

 Define the term ‘element’
 Name and write symbols of common
elements
 Develop an understanding of the structure of
the Periodic Table

 Elements are made of only one kind
of atom
◦ Gold is made of gold atoms
◦ Carbon is made of carbon atoms
◦ Hydrogen is made of hydrogen atoms

 Elements have been put in order of:
 Physical properties
 Chemical properties
 Atomic number
 Mass number
 Number of electrons in outer shell
on the Periodic Table of
Elements

1) Hydrogen
2) Helium
3) Lithium
4) Beryllium
5) Boron
6) Carbon
7) Nitrogen
8) Oxygen
9) Fluorine
10)Neon
11) Magnesium
12)Aluminium
13)Silicon
14)Phosphorus
H
He
Li
Be
B
C
N
O
F
Ne
Mg
Al
Si
P

15)Sulphur
16)Chlorine
17)Argon
18) Calcium
19) Zinc
The less obvious ones:
1) Sodium
2) Potassium
3) Iron
4) Copper
5) Silver
6) Tin
7) Gold
8) Mercury
9) Lead
S
Cl
Ar
Ca
Zn
Na
K
Fe
Cu
Ag
Sn
Au
Hg
Pb

 Element Song
 Daniel Radcliff

 Video
 http://www.youtube.com/watch?v=1PSzSTilu
_

20/01/2015
Mendeleev
The periodic table arranges all the elements in groups
according to their properties.
Horizontal rows are called PERIODS
Vertical columns
are called GROUPS

20/01/2015
H He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Fe Ni Cu Zn Br Kr
Ag I Xe
Pt Au Hg
Fact 1: Elements in the same group have the same number of
electrons in the outer shell (this corresponds to their group
number)
E.g. all group 1 metals
have __ electron in
their outer shell
These elements
have __ electrons in
their outer shell
These elements have
__ electrons in their
outer shells

20/01/2015
H He
Li Be B C N O F Ne
Ag I Xe
Pt Au Hg
Fact 2: As you move down through the periods an extra electron
shell is added:
E.g. Lithium has 3
electron in the
configuration 2,1
Potassium has 19 electrons in
the configuration __,__,__,__
Sodium has 11
electrons in the
configuration 2,8,1

20/01/2015
H He
Li Be B C N O F Ne
Ag I Xe
Pt Au Hg
Fact 3: Most of the elements are metals:
These elements are
metals
This line divides
metals from non-
metals
These elements are non-
metals

20/01/2015
H He
Li Be B C N O F Ne
Ag I Xe
Pt Au Hg
Fact 4: (Most important) All of the elements in the same group
have similar PROPERTIES. This is how I thought of the periodic
table in the first place. This is called PERIODICITY.
E.g. consider the group 1 metals. They all:
1) Are soft
2) Can be easily cut with a knife
3) React with water

 Metals on the _____
 Non Metals on the ______
 Rows tell us the number
of electron shells an
element has
 Groups tell us the number
of electrons in the outer
shell

 Complete Scipad page 11and 13

 Determine the structure of an atom based on
data from the periodic table
 Draw the arrangement of electrons around
any given atom
 Use the electron arrangement of an atom to
identify which group on the periodic table it
belongs too.

 What is the difference between Gold and Oxygen?
 Elements are made up of one kind of atom only
 Elements have been put in order of:
 Physical properties
 Chemical properties
 Atomic number
 Mass number
 Number of electrons in outer shell
on the Periodic Table of Elements

Atomic Number:
 Smaller number
 Number of protons
 Number of electrons
Atomic Mass or Mass Number:
 Bigger number of the two
 Total number of sub atomic particles
 Number of protons + neutrons.

How do we work out the number of:
 Protons
= Atomic number
 Electrons
= Atomic number
 Neutrons
= Mass number – atomic number
Fill in first 5 columns of Elemental information
sheet

 Electrons arrange themselves in regular order
around the nucleus depending on their energy.
 Each energy level holds a different number of
electrons:
◦ Level 1 – 2 electrons
 Electrons fill from Level 1 shell, or the closet to the
nucleus first.

Calculating electron arrangement using the
periodic table:
 Row/Period gives us the number of electron
shells
 Group tells us the number of electrons in outside
shell
Eg Sodium – row 3 – three shells
- group 1 – 1 electron in outside shell
- electron arrangement = 2,8,1

 Fill in columns 9, 10, 11 on elemental
information sheet.
 Draw dot diagrams for the first 5 elements H,
He, Li, Be, B) (use dots for electrons, and draw
shell lines in pencil, use blue pen for protons
and red for neutrons)
 Complete Scipad pages 12, 15, 16

 http://lgfl.skoool.co.uk/content/keystage4/c
hemistry/pc/lessons/uk_ks4_atoms_periodic_
table/h-frame-ns6.htm

 Describe the role of electrons in chemical
reactions
 Describe how positive and negative ions are
formed
 Write the name and formula of common ions

Two atoms are walking down the street.
Says one atom to the other, "Hey! I think I lost
an electron!"
The other says, "Are you sure??"
"Yes, I'm positive!"

 Chemical reactions occur when atoms gain or
lose electrons
 The fewer electrons that are gained or lost
the more reactive atoms are.

 Atoms require their outer shells to be full in
order to be chemically stable
 Atoms either lose or gain electrons to get a
full outer shell (2,8,8)
 When atoms lose or gain electrons they
become electrically charged and are then
called ions
 Gaining electrons (-ve) results in a ________
ion
 Losing electrons results in a __________ ion
 The number of protons (+ve) stays the same

E.g
Na  Na+ + e-
Sodium atom sodium ion Free electron
2, 8, 1 2, 8,
Cl + e-  Cl-
Chlorine atom electron Chlorine ion
2, 8, 7 2, 8, 8
The charge on an ion is called its valency.
Valency always has a sign (+ or -) and a numerical
value. (although we don’t write 1)
Complete ion information on elemental sheet

 Ionic compounds:
 Have equal numbers of + and – charges
 Made up of metal and non metal
 Named by the ions they contain
 Metal part goes first, then non metal
 If non metal ion is made up of two or more
elements change end to ate,
 SO4 – sulphate
 only 1 element in non metal ion it ends in ide
 NaCl = sodium chloride

 How do you know if an atom will gain or lose
electrons?
Eg. Na 2,8,1
- is it easier to lose one electron or gain 7?
- Hence Na looses a negative electron to become:
- Na+
Eg. Cl 2,8,7
- is it easier to gain one electron or lose 7?
- Hence Cl gains a negative electron to become:
- Cl-

Information Na Be Cl
Atomic Number
Mass Number
Protons
Neutrons
Electrons
Electron Config.
Gain/Lose
Electrons
+ve/-ve charge
Ion Formed
Ion electron
config.
Protons:
Electrons in Ion

 Complete Scipad pages 17-19
Magnesium and calcium atoms both form ions with
a charge of +2. Magnesium atoms form Mg2+ ions,
and calcium atoms form Ca2+ ions.
Explain why magnesium and calcium atoms form
ions with the same charge of +2. In your answer,
you should:
 define an ion
 explain why atoms form ions
 identify the group on the periodic table where
the two atoms are found
 explain why both magnesium and calcium ions
have a charge of +2.

Definition of an ion:
An ion is an atom or group of atoms that have lost
or gained an electron and therefore carry a charge.
Explanation of formation of ions:
If the outer shell (valence) of an atom is not filled,
the atom is unstable. It will react to gain a full
outer shell to become more stable, by either losing
or gaining electrons and making it into an ion.
Identification of Group:
Magnesium and calcium are in the same group on
the periodic table Group 2 – both have two
electrons in outside shell.

Explanation of why both form+2 ions:
The atoms have the same number of electrons
(two) in their outer shell. 2,8,2 and 2,8,8,2
Both Mg and Ca need to lose two outer
electrons to become stable by having a full
outer shell.
Each ion (Mg2+ and Ca2+) ends up with two less
electrons(negative) than there are
protons(positive) in its nucleus, so the ion has
a charge of +2.

 Describe ionic bonding
 Use ions to write the name and formula of
compounds
 A sign outside the chemistry hotel reads
"Great Day Rates, Even Better NO3
-'s"

Positive Ions Negative Ions
+1 +2 +3 -3 -2 -1
H+
Hydrogen
Ion
Mg 2+
Magnesium
Ion
Al3+
Aluminium
Ion
N3-
Nitrite Ion
O2-
Oxygen ion
Cl-
Chloride ion
Li+
Lithium Ion
Ca2+
Calcium Ion
Fe3+
Iron III ion
P3-
Phosphide
ion
S2-
Sulphide ion
Br-
Bromide ion
Na+
Sodium Ion
Fe2+
Iron II ion
PO3-
4
Phosphate
Ion
CO2-
3
Carbonate
ion
I-
Iodide ion
K+
Potassium
Ion
Cu2+ SO2-
4
Sulphate Ion
NO-
3
Nitrate ion
Ag+
Silver Ion
Zn2+ HCO-
Hydrogen
carbonate
ion
NH+
4
Ammonium
Ion
Pb2+ OH-
Hydroxide
ion

Ionic compounds have an overall neutral charge.
Therefore there must be equal numbers of positive and negative
charges.
◦ Magnesium Nitrate Mg2+NO3
-1
Mg+ Mg+ NO3
-1
◦ 2 positives and one negative
what is needed to balance the charges?
◦ Another negative or (NO3
-1)2
Mg2+(NO3
-1)2 - we need another whole anion so use brackets

 Write out symbols from table
 Put brackets around ions with two
elements (two capitals) eg SO2-
4
 Count the number of positives and
negatives
 Balance charges by multiplying ion
 Check it balances
 Rewrite without charges

Formulas show how many atoms of each type
are in a compound
 The bottom right hand number tells us how
many of the atoms directly before it there
are.
◦ H20 = 2 hydrogen atoms, one oxygen atom
 We don’t write 1 in as we are lazy!

 The number directly outside a bracket is a
multiplier of everything inside the bracket.
◦ Al(OH)3 = 1 Al, 3 O, 3 H
◦ (NH4)3PO4 = 3N, 12 (3x4) H , 1P, 4 O
To get the total number of atoms we work
out how many of each atoms there are and
then add them
◦ (NH4)3PO4 = 3N, 12 (3x4) H , 1P, 4 O
◦ 3+12(3x4)+1+4 = 20 atoms

 A big number in front means two of the
whole compound – so work out how many
of each atom there is, add them up and
then multiply this by the big number at the
front.
◦ 2(NH4)3PO4 = 3N, 12 (3x4) H , 1P, 4 O
◦ 3+12+1+4 = 20 atoms
◦ 20 x 2 = 40 atoms

 Explain why the ions in sodium hydroxide combine to
give the formula NaOH but the ions in beryllium
hydroxide combine to give the formula Be(OH)2.
In your answer, you should:
 compare the charges on the individual ions found in
the compounds sodium hydroxide and beryllium
hydroxide
 explain why the ions combine in the ratios the way
they do to form the compounds NaOH and Be(OH)2.

Comparison of charges on ions:
When these elements react, Na loses one electron
and forms a +1 ion, while Be loses two electrons
and forms a +2 ion in order to adopt the stable
electron configuration. The hydroxide carries a
charge of -1.
Explanation of formation of compounds:
 An ionic compound is electrically neutral
therefore all the positive charges must balance
the negative charges.
 Therefore it requires one OH-1 for each Na+ ion
but two OH-1 ions for each Be2+ ion to form a
neutral compound/ balance the charges.

Explain why the ions formed by sodium and
oxygen both have the same electron
arrangement.
In your answer you should:
• describe an ion
• describe the atomic structures of a sodium
ion and an oxide ion
• state the charge on the sodium ion and the
oxide ion
• explain the charges on both ions in terms of
electron arrangement and number of protons

Element X is between numbers 11 and 18 on the
Periodic Table.
An atom of element X forms an ion. This ion
combines with the hydroxide ion to form a neutral
compound, X(OH)3.
Determine what element X is and justify your
answer.
• consider the ratio of X ions to hydroxide ions
• use the formula X(OH)3 to determine the charge
of the X ion
• explain how you would use the Periodic Table in
your Resource Booklet to find out which group
element X is in
• name element X.

 Write word equations for chemical reactions
 Balance chemical equations

 Reactant  Product
 There has to be the same number and type
of each atom on both sides of the arrow –
this is how you check you have balanced
the equation correctly!
 There are three types of equations
◦ Word equations (don’t need atoms balanced)
◦ Symbol equations
◦ Ionic equations (not need for level 1)

Step 1: Write out word equation
Magnesium + oxygen  Magnesium oxide
Step 2: Write out symbol formula
Mg + O2  MgO
Step 3: Count atoms of each kind on each side
1 Mg 2 O  1 Mg 1O

Step 4: Identify the atoms with different numbers
2 oxygen atoms on left one on right
Step 5: Increase atoms by putting number:
 in front of compound (2H2O) – makes 4 H & 2 O
 after an ion (Mg2) – makes 2 Mg
 brackets and a subscript around polyatomic ions
(SO4)2 –makes 2 S & 8 O
Do hydrogen then oxygen atoms first
Mg + O2  2MgO

Step 6: Count atoms of each kind on each side –
they will have changed as a result of step 5!!!!
1 Mg 2 O  2 Mg 2O
1 Mg on left & 2 on right
Step 8: Increase atoms numbers
2Mg + O2  2MgO

Step 1: Write out word equation
Sodium + Water  Sodium Hydroxide + Hydrogen
Step 2: Write out symbol formula
Na + H2O  NaOH + H2
1 Na, 2 H, 1 O  1 Na, 1 O, 3 H
2 H  3 H
Step 5: Increase atoms by putting number:
Na + 2H2O  2NaOH + H2

1 Na 4H 2 O  2 Na 2 O 4H
1 Na on left and 2 on right
Step 11: Increase atoms numbers
2Na + 2H2O  2NaOH + H2

2 Na 4H 2 O  2 Na 2 O 4H
Same type of atoms and same number of atoms
on both sides – DONE!
Nobody said it’d be easy but it does get easier,
and remember practice makes perfect!

 http://misterguch.brinkster.net/eqnbalance.h
tml
 http://www.files.chem.vt.edu/RVGS/ACT/not
es/scripts/bal_eq1.html
 http://www.sciencegeek.net/Chemistry/tater
s/EquationBalancing.htm
 Complete Sci pad pages 28-31

 Complete Scipad pages 8-9, 32-35
 Complete purple book pages:
 Complete worksheets:

 http://www.youtube.com/watch?v=_rsqBNhF
G1Y

 In order for a reaction to occur particles need
to collide
 Particles need to collide with enough force to
break bonds and form new ones
 The more successful collisions the faster a
reaction occurs
Complete Rates of Reaction Experiments

More successful collisions can be caused by:
◦ Increasing the temperature (particles move faster so
collide more)
◦ Increasing the concentration (more particles to collide)
◦ Increasing surface area (small particles have greater
surfaces for collisions to occur)
◦ Use a catalyst (holds chemicals so collisions can occur,
lowers activation energy needed to break bonds)
◦ Increase pressure (particles are closer together
therefore collide more often)
Increasing collisions increases rate of reaction!

 What is the difference between particle theory and
collision theory
 Complete Rates of Reactions Experiments
 Complete worksheets
 Complete scipad pages 37-39, 48-53
 Complete pages 40-47 (all the equipment you
need is up the front)
 http://www.kscience.co.uk/animations/collision.h
tm

 Particle theory – all matter is made up of particles
which are in constant motion
 Collision theory – particles need to collide with
enough force and energy to break bonds and
form new ones
 More particles  more collisions  faster rate of
reaction
 More movement  more collisions  faster rate
of reaction

Calcium carbonate (marble chips) and hydrochloric acid
react together in a conical flask.
The word equation for this reaction is:
calcium carbonate + hydrochloric acid → calcium chloride +
water + carbon dioxide gas
(a) Describe an observation you would make when this
reaction occurs.
(b) Explain why the mass decreases with time.
When more concentrated hydrochloric acid is used, the
reaction is faster.
© Explain the difference in the rate of reaction.
In your answer you should refer to:
• particles
• collisions
• reaction rate.

Fizzing / bubbling occurs, marble chips decrease in size, heat is produced.
Why mass decreases
The marble chips decreases as one of the products is CO2 gas. This gas
escapes and so the mass of the flask and contents is reduced.
What’s happening
As the reactant particles collide, they form product particles. As the
reaction proceeds, there are fewer and fewer reactant particles left to
collide and so the rate of reaction becomes slower.
At the start (section X) of the reaction, more product particles are being
formed, then more gas is being formed, therefore more gas escapes at first
and so the mass of the flask and contents decreases more rapidly. At X, the
rate of reaction is fast but decreasing with time.
In section Y there are now fewer (less) reactants and so there are fewer
collisions per second (unit time) and so less product is formed, ie less gas
being released, so the mass does not decrease as rapidly. At Y, the rate of
reaction is slow and slowing.
In section Z the reaction has stopped, as one of the reactants (marble chips
or HCl) has run out, so there are no particles left to react.

When more concentrated acid is used, there are
more acid particles in the same volume of the
acid. Because of this, there are more particles
to collide with the calcium carbonate. Because
there are more to collide, the rate of reaction is
faster.
Explains why the reaction is faster, by linking
the idea that there are more acid particles in
the same unit volume available for collisions,
and hence there will be more collisions,
causing the faster reaction rate

hemistry/pc/lessons/uk_ks4_rates_of_reactio
n/h-frame-ns6.htm

 Define the terms acid, base and alkali
 Name and write the formula of three common
laboratory acids
 Classify acids and alkalis as chemicals with
distinct properties and uses.

Substance Acid
(red/orange)
Base
(purple/blue)
Neutral
(green)

 Taste sour
 pH less than 7
 Turn litmus red
 Contain hydrogen ion H+
 Conduct electricity
 Acid rain (oxides of sulphur and nitrogen from
factories dissolve in water to form acid rain)
 citric juice, stomach acid (HCl), vinegar, battery
acid
 Acid reactions:
◦ Acid + base  salt + water
◦ Acid + metal  salt + hydrogen gas
◦ Acid + carbonate  salt + water + carbon dioxide

 Taste bitter, Feel slippery
 pH greater than 7
 Turn litmus blue
 Alkali is a base that is soluble in water
 Metal oxides and metal hydroxides
 Most contain OH- ion, hydroxide ion
 Conduct electricity
 Soaps, oven cleaners (NaOH)
 Antacids (Mg(OH)2) – neutralise stomach acids
 Floor cleaners, bleach (ammonium hydroxide)
 Calcium hydroxide is limewater
 Calcium hydrogen carbonate – limestone caves
 Used to neutralise acids:
◦ Neutralisation
◦ HCl + NaOH  NaCl + H2O = pH 7
◦ Acid + Base  salt + water

Common Name Chemical
Name
Formula Acid Base
Vinegar
Lemon juice
Grape juice
Soda Water
Antacids
Floor Cleaner
Battery Acid
Stomach Acid
Nitric Acid
Hydrochloric Acid
Magnesium oxide

Common Name Chemical Name Formula Acid Base
Vinegar Acetic Acid C2H4O2
Lemon juice Citric Acid C6H8O7
Grape juice Tartaric Acid C4H6O6
Soda Water Carbonic Acid H2CO3
Antacids Magnesium Hydroxide MgOH
Floor Cleaner Ammonium Hydroxide NH4OH
Battery Acid Sulphuric Acid H2SO4
Stomach Acid Hydrochloric Acid HCl
Nitric Acid Nitric Acid HNO3
Hydrochloric Acid Hydrochloric Acid HCl
Magnesium oxide Magnesium oxide MgO

 Complete Scipad pages 58-59 What is an
Acid, What is a Base
 List three common household acids and their
formulas
 List three common household bases and their
formulas

 Use the pH scale to compare the acidity and
alkalinity of different solutions

We use a pH scale to tell us how acidic, basic or
neutral a substance is.
Acids have a pH range from 1-6
Alkalis or bases have a pH range from 8-14
Neutral substances have a pH of 7

 Strong acids contain more
free H+ ions
 Strong bases contain more
free OH- ions
 Most naturally occurring
substances are weak eg.
Citric acid in citrus fruit

 Complete Scipad Investigations pages 61-62
Testing pH and Making Indicators
 Complete Scipad page 63

 Name and write the formula for various metal
oxides, metal hydroxides, metal carbonates
and hydrogen carbonate

 Metal oxides
 contain oxide ion O2-
 Rust Iron oxide FeO, Zinc oxide (sunscreen) ZnO
 Basic
 Acid + Metal Oxide  Metal Salt + Water
 Metal Hydroxide
 Contain hydroxide ion OH-
 Antacids Magnesium hydroxide MgOH
 Form when metal or metal oxide reacts with water
 Acid + Metal Hydroxide  Metal Salt + Water

 Metal Carbonates
 Contain the carbonate ion CO3
-
 Calcium carbonate CaCO3
- marble chips
 Release carbon dioxide when react with acids
 Acid + Metal Carbonate  Metal Salt + Water
+ Carbon Dioxide
 Metal Hydrogen Carbonates
 Contain hydrogen carbonate ion HCO3
-
 Neutralise acids
 Produce carbon dioxide when reacted with acids
 Calcium hydrogen carbonate CaHCO3
 Acid + Metal Hydrogen Carbonate  Metal Salt
+ Water + Carbon Dioxide

Name Metal Type Formulae
Copper oxide
CuCO3
Lithium hydroxide
FeO
Zinc carbonate
MgOH
Calcium hydrogen
carbonate

 Describe neutralisation reactions
 Identify the products of neutralisation
reactions

 When we add base to an acid, a chemical reaction
takes place.
 The acid and base are used up in the reaction.
 We say they are neutralised. They make a salt
and water.

When a substance has been neutralised or is
neutral it has a pH of around 7.
Acid + Base  Salt + Water

Aim: To neutralise an acid using a base.
Method:
Step 1: Add four drops of sodium hydroxide to a test
tube.
Step 2: Add one drop of universal indicator to the test
tube and shake.
Step 3: Stop when the solution is green, if the solution
turns red or orange add a very small drop of NaOH
until the liquid turns green.

 Complete Scipad practical page 64
Neutralisation
 Complete scipad page 65

What causes indigestion?
-to much acid in the oesophagus
What do we need to add to neutralize that acid?
- Base! – Antacid, quickeze, mylanta, gaviscon
etc

Iron Magnesium Zinc Copper Lead
Hydrochloric
Acid
Sulphuric
Acid
Zinc
Sulphate
ZnSO4 No
Reaction
Nitric
Acid
Salts are named after the acids from which they are formed.
• Hydrochloric acid forms chloride salts
• Sulphuric acid forms sulphate salts
• Nitric acid forms nitrate salts

hemistry/pc/lessons/uk_ks4_acids_alkalis_sal
ts/h-frame-ns6.htm

 Complete pages 93, 94, 95
A student puts 5 mL of dilute hydrochloric acid into a boiling tube and adds
five drops of universal indicator to the solution. The student then takes a
solution of sodium hydroxide of the same concentration as the acid and adds
it one drop at a time to the acid until the colour stops changing.
 Describe the colour of the universal indicator solution:
◦ in the hydrochloric acid before any sodium hydroxide was added.
◦ when the sodium hydroxide was added and the colour of the solution stopped
changing.
As the sodium hydroxide is added several colour changes occur.
 Explain how the colour changes relate to pH AND what ions are present in
the solution colour changes.

Description of colour changes:
 red /pink to start with
 blue /purple /violet at end.
Explanation of colour changes:
At the beginning the red indicated a low pH due to excess H+ ions in the solution.
As the NaOH was added, a yellow /green colour indicates a pH of around 7, due to
the OH- ions combining with the H+ ions to form a neutral solution.
As more NaOH is added the blue /purple indicated a pH of 11 plus, due to excess
OH- ions in the solution.
Identification of reaction type:
Acid-base (or acid-carbonate) neutralisation (the carbonate ions react with the H+
ions of the acidic solution and neutralise the solution).
Description of observations:
Bubbling in the solution /fizzing /effervescence /frothing /foaming Ca2CO3
disappears.
Linking observations to products:
The products are CO2, H2O and a salt. The CO2 gas causes the bubbles /fizzing /etc.
Writing a word equation:
Nitric acid + sodium carbonate  sodium nitrate + water + carbon dioxide
Writing a symbol equation:
2HNO3 + Na2CO3  2NaNO3 + H2O + CO2

A student put 10 ml of dilute nitric acid in a boiling
tube with five drops of universal indicator. Sodium
hydroxide of the same concentration was then
added. The following observations were recorded.
Discuss the reaction occurring as sodium
hydroxide is added to the nitric acid.
• explain the relationship between the colours
observed and the pH of the solution
• explain which ions cause the different colours of
the solution
• write a word equation for the reaction AND a
balanced symbol equation for the reaction.

 Write word and symbol equations for a
range of reactions involving acids and bases
 Describe some everyday uses of acids,
alkalis and neutralisation

 Acid + Base  Salt + Water
 Hydrochloric acid + sodium hydroxide
 sodium chloride + water
 Test to see if reaction is complete by using
indicator – solution should turn
Green

 Complete scipad pages 66-68 Writing
chemical equations
 Complete Scipad practical Making Salts, page
69

 Acid + Carbonate
 Salt + Water + Carbon dioxide
 Sulphuric Acid + Copper Carbonate
 Copper sulphate + water + Carbon dioxide
 We test for Carbon dioxide by bubbling the gas
into lime water which turns
milky

Limewater (calcium hydroxide) reacts with carbon
dioxide to produce a precipitate of calcium
carbonate:
Ca(OH)2 (aq) + CO2 (g) → CaCO3 (s) + H2O (l)
Limewater + carbon dioxide  calcium carbonate + water
If excess CO2 is added, the following reaction
takes place:
CaCO3 + H2O + CO2 --> Ca(HCO3)2 (colourless)
Calcium Carbonate + water + carbon dioxide  calcium bicarbonate

 Complete Scipad practical page 70
Carbonates and Acids
 Complete Scipad page 71-73

 Acid + Metal  Salt + Hydrogen Gas
 Nitric Acid + magnesium
 magnesium nitrate + hydrogen gas
 We test for hydrogen gas by doing the
POP test

 Acid + Base  Salt + Water
 Acid + Carbonate
 Salt + Water + Carbon dioxide
 Acid + Metal  Salt + Hydrogen Gas

A student wanted to make the salt, magnesium
chloride.
Discuss how the student would make magnesium
chloride salt from hydrochloric acid and magnesium
oxide.
• state what type of reaction occurs
• write a word equation AND a balanced symbol
equation for the reaction between hydrochloric acid
and magnesium oxide
• explain how you would make magnesium chloride in
a school lab from hydrochloric acid and solid
magnesium oxide (this can be done by drawing labelled
diagrams).

Type of reaction
Acid-Base reaction or neutralisation.
Word Equation
hydrochloric acid + magnesium oxide → magnesium
chloride + water.
Balanced Equation
2HCl + MgO → MgCl2 + H2O
How to make it
Add magnesium oxide to hydrochloric acid in a beaker.
Heat slightly and pour this into an evaporating dish and
leave somewhere warm (e.g. window sill) for a few days
or heat over Bunsen to speed up the reaction, so that
the water can evaporate, leaving magnesium chloride
salt. Safe lab procedure would include dealing
appropriately with chemicals such as HCl or the
wearing of safety glasses

 Brainstorm connecting words
 Read the question and answer on the sheet,
◦ highlight the connecting terms,
◦ use the marking schedule to mark it.
 Swap and complete one more question
 Complete questions on worksheet
◦ Use connecting terms!
 Complete Scipad practice NCEA exam under exam
conditions pages 80-85, mark it!!

 Atoms and ions
◦ Structure of an atom, number of protons, neutrons,
elections, electron configuration
◦ Isotopes
◦ Ion formation
◦ Ionic compounds
 Rates of reactions
◦ Particle theory
◦ Factors affecting rate
◦ Observations and tests for gases
 Acids reactions
◦ Properties of acids and bases
◦ Common acid equations
◦ pH, indicators and neutralisation
◦ Word equations and balanced equations

Acids and Bases 2014 GBL

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