Transcript Acids and Alkalis

CKS3: Yr7 Chemistry Unit 1 – Me the the Scientist!
Lesson number: 4.
Lesson Title: Acids and Alkalis
Learning Outcomes
Learning Outcome 1:
Use the pH scale to identify the pH
of different acids and alkalis
Level 5
How I did
Targets
Connector:
• List 3 common acids and 3
common alkalis and how they
are used at home.
Learning Outcome 2:
Link pH of an acid or alkali to how
hazardous or corrosive it is.
Level 6
Learning Outcome 3:
Link strength of an acid to how
corrosive it is.
Level 7
07:38
Cro2011
New Information for Task 1
• Acids and alkalis are groups of chemicals.
ALKALI
ALKALI
ACID
ACID
NEUTRAL
ACID
ALKALI
Acids and alkalis
When a substance dissolves in water it
makes a solution.
Solutions can be sorted by whether they
are: acid, alkali or neutral.
http://www.bbc.co.uk/learningzone/clips/universal-indicator-acid-alkalior-neutral/121.html
New
for Task
1alkalis
ALKALIS
SomeACIDS
factsInformation
about acids
and
Sharp, sour taste
Soapy feel
Strong acids can corrode (eat away) metals,
e.g. hydrochloric acid
Strong alkalis can corrode metals, e.g.
sodium hydroxide
Some can burn living tissue, e.g. battery
acid, other kinds won’t, e.g. lemon juice
Can be caustic (burn living tissue), e.g.
caustic soda for oven cleaning
Some are hazardous, e.g. sulphuric acid,
some are harmless, e.g. vinegar
Some are hazardous, e.g. sodium
hydroxide, some are harmless, e.g. sodium
bicarbonate (baking powder)
Neutralise (cancel out) alkalis
Neutralise (cancel out) acids
Turn litmus indicator RED
Turn litmus indicator BLUE
Have a pH of 1-6
Have a pH of 8-14
Examples
Examples
hydrochloric acid
sulphuric acid
nitric acid
citric acid (lemons, oranges etc)
vinegar
soap (Johnson’s pH 5.5)
Sodium hydroxide (caustic soda)
ammonium hydroxide (ammonia)
calcium hydroxide (limewater)
Washing powder
Oven cleaner
soap
BIG picture
Key Question: How can you determine if a chemical is an acid or an alkali?
What skills will you be developing this lesson?
HSW- by planning and carrying out an investigation/
Interpreting data/ evaluating an experiment
ICT- through using laptops
Numeracy- by using formulae in calculations
Literacy- by writing explanations using correctly spelt
keywords and good grammar.
Team work- during a practical investigation
Self management- by completing an individual assignment
by …..
Creative thinking- by designing a ……………….
Independent enquiry- by researching the internet
Participation- during a practical activity
Reflection- through self and peer assessment of each
outcome
07:38
How is this lesson relevant
to every day life?
There are many acids and
alkalis present in our
everyday lives.
Quick Discussion: What do
you already know?
Keywords:
Create sentences using the keywords to show that you know what they mean.
Put your hand up if there is any key word from the list that you don’t understand.
• Acid
• Alkali
• Solution
• pH
•
•
•
•
•
• Indicator
• Universal Indicator
• Sour taste
• Soapy feel
• Caustic
07:38
Irritant
Strong
Weak
Corrode
hazardous
New Information for Learning Outcome 1
• Visual: Demonstration
• http://www.bbc.co.uk/learningzone/clips/universal-indicatoracid-alkali-or-neutral/121.html
• Audio: Demonstration
• Kinaesthetic: Class experiment
07:38
What is the pH scale?
The strength of an acid or alkali is measured by the pH scale.
Each universal indicator colour is given a number called
the pH value.
Universal indicator can tell you the pH of a solution.
stronger acid
stronger alkali
1 2 3 4 5 6
7 8 9 10 11 12 13 14
strong
acid
weak
weak
acid neutral alkali
What is the pH of a weak acid?
What is the pH of strong alkali?
strong
alkali
Copy into books
Task 1 (Level 5)
• Task 1:
• Predict from the range of
household substances which
ones you think are acids and
alkalis, write them down in
predictions
• Task 1: Extension
• Group the substances into
strong and weak acids and
strong and weak alkalis
Keywords for Task 1:
• Acid
• Alkali
• Weak Acid
• Weak Alkali
• pH
• Universal indicator
•
Copy and complete
Substance
Milk
Apple juice
Orange juice
Lemonade
Cola
Vinegar
Bleach
Water
Prediction,
acid or
alkali?
Colour and
pH
Acid or
alkali?
What type of substance?
Are these substances acidic or alkaline?
Are they weak or strong?
Substance
soda water
car battery acid
1
Description of acid/alkali
very weak acid
very strong acid
soap
8
very weak alkali
washing soda
10
weak alkali
stomach acid
2
strong acid
oven cleaner
14
very strong alkali
vinegar
4
weak acid
acid
pH
6
1 2 3 4 5 6
7
8 9 10 11 12 13 14
alkali
Demonstrate your Learning
for Outcome 1
Apply (L5)
Can you use a storey
board to explain how to
identify if a household
substance is an acid, alkali
or neutral
Create
I am working at level ....
because ...........
Evaluate
Understand (L4)
Analyse
Apply
Understand
Remember
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Did you:
1. Complete the
experiment ?
Can you classify different
household substances into
acid or alkali?
Extended Learning
Extended Learning task:
• Make a poster display of all the different acids and alkalis in the
home and their different uses.
• e.g. Vinegar is an acid and it can be used in homes to make
pickles.
Due date:
Criteria for Level 5:
– Basic description, basic detail.
Criteria for Level 6:
– Description with explanation and good level of detail.
Criteria for Level 7:
– Detailed description and in depth detailed explanation using examples
to highlight points made.
07:38
Learning Outcome 1: Review
To carry out an experiment to identify and classify
household substances into acids and alkalis
Go back to your Learning Outcome grid and fill out the
‘How I did’ and the ‘Targets’ column.
Learning Outcome
Learning Outcome 1:
Level 5
07:38
How I did
Met?
Partly met?
Not met?
Targets
How can I improve
on Learning
Outcome 1?
New Information for Learning Outcome 2
What are hazard symbols?
How can you tell which chemicals are safe and which are
dangerous?
Special symbols are used on bottles and vehicles that
contain dangerous chemicals.
i
toxic
irritant
h
harmful corrosive
highly
flammable
These hazard symbols show why the chemical is dangerous.
Why is it important that these symbols can be recognised by
people from other countries?
7E Acids and alkalis - Concentrated and dilute
Compare the particle model of a concentrated acid with a
weak acid.
concentrated acid
weak acid
Which sentence best describes which acid?
A. This acid has only a few acid
particles compared to water
particles.
B. This acid has a lot of acid
particles compared to water
particles.
Why is a dilute acid less hazardous than a concentrated acid?
Demonstrate your
Learning for Outcome 2
I am working at level ....
because ...........
Create
Evaluate
To get to the next level I
need to ...........
Analyse (L6)
Apply (L5)
Analyse
Did you:
Apply
1. Do a storey board to
explain what happen
when UI is added to a
substance
Understand
2. Identify the colour
change with UI?
Remember
07:38
Did you:
1. Draw a poster to identify
hazard warning symbols
2. Include pictures of the
chemicals and
information about how to
use it safely in the lab?
3. Explain why dilute acid is
less hazardous
Learning Outcome 2: Review
To carry out an experiment to investigate the heating
effect of different bunsen flames.
Go back to your Learning Outcome grid and fill out the
‘How I did’ and the ‘Targets’ column.
Learning Outcome
Learning Outcome 2:
Level 6
07:38
How I did
Met?
Partly met?
Not met?
Targets
How can I improve
on Learning
Outcome 2?
Learning Activities for Outcome 3
Extension – Linking the strength of an acid to how
corrosive it is
Task 7:
Draw a line, and add substances to it to show how
hazardous or corrosive you think the household
substances are
Task 2: Extension
Name a very harmful acid and very harmful alkali
Task 3: Answers
h
Harmful and corrosive
Strong acids and Alkalis
Not harmful
Weak acids and alkali
Learning Outcome 3: Review
Go back to your Learning Outcome grid and fill out the
‘How I did’ and the ‘Targets’ column.
Learning Outcomes
Learning Outcome 3:
Level 7
07:38
How I did
Met?
Partly met?
Not met?
Targets
How can I improve
on Learning
Outcome 3?
Review for Remembering
• Stand up if you have met the lesson outcomes?
• If not what do you need to do next in order to meet
the outcome? Record this in your diary as part of
your homework.
• Is there any part of the lesson you think you need to
go over again next lesson?
• Tell the person next to you three things you have
learnt this lesson.
• How will you remember this for your exam?
07:38
Technician’s list
Apparatus and chemicals
Eye protection
Universal Indicator
• fizzy drinks
• tap water
• de-ionised/distilled water
• toothpaste
• shampoo
• soap
• vinegar
• lemon juice
Technical notes
1 Provide small amounts of the samples on watch glasses. The watch glasses can be placed on a white
tile marked with the name of the substance - use a waterproof marker.
2 The samples can be arranged around the room so that the students visit each in turn. If any solid
sample is used, moisten it with a little de-ionised water.