Year 8 CHEMICAL CHANGE Chapter 8
Key Concepts
Words To Learn



1. Patterns, Order & Organisation
2. Time For Some Changes
3. Chemical Reactions
4. Fast & Slow Reactions
5. Rusting out
6. Burning Is A Chemical Reaction
7. A New Breed Of Materials
Physical properties, ductile, malleable, elasticity, Chemical properties, flammability, reactivity, toxicity, chemical change, evaporate, physical change, reactants, products, explosion, reaction rate, catalyst, enzyme, rusting, corrosion, galvanising, oxidation, burning, combustion, plastics, natural fibres, nylon, polyester, spinneret, biodegradable.
NAME:


Science Quest 8
TEXTBOOK
PRACTICALS / ACTIVITIES
SCIENCE Quest 8
Understanding
ACTIVITIES
Established Extending

1
8.1 Patterns, Order & Organisation
8.2 Time for Some Changes
Suggestions:
AssessOn Ch 8 Pretest
8.1 Checking Out Properties (not Discuss & Explain) page 251
8.2 A Burning Candle page 252

http://www.dailymotion.com/video/x3jyupa
Understanding & Inquiring
page 251 Q’s 1, 3, 4, 5
page 253 Q’s 1 – 8
Understanding & Inquiring page 251 Q’s 6 - 8
page 253 Q 9
Do item 3. Discuss & Explain on page 251

2
8.3 Chemical Reactions
8.3 Magnesium metal in hydrochloric acid page 255
8.4 Heating copper carbonate page 255
8.5 Sodium sulfate & barium chloride page 255
8.6 Steel wool in copper sulfate page 255
Understanding & Inquiring
page 256 Q’s 1, 2
Understanding & Inquiring page 256 Q’s 4 & 5
Understanding & Inquiring page 256 Q’s 6 & 7

* CREATE – page 256 do Question 9 and present your findings to the class

3


8.4 Fast & Slow Reactions
8.7 The effect of temperature on the rate of reaction page 258
8.8 Changing the rate of reaction page 259
(Check out Jacplus Searchlight ID: int-0230)
Understanding & Inquiring
page 259 Q’s 1 - 6
Understanding & Inquiring page 259 Q’s 7 - 9
Understanding & Inquiring page 259 Q 11

4
8.5 Rusting Out
8.9 Observing Rusting page 260
eBook Plus – How Rust Works (WS8.6)

Optional: 8.11 Rusting & Salt Water page 262
Understanding & Inquiring
page 262 Q’s 1 - 4
Understanding & Inquiring
page 262 Q’s 5 - 8
Understanding & Inquiring
page 262 Q 10

5
8.6 Burning Is a Chemical Reaction
8.12 Burning magnesium page 264
Check out: Youtube Combustion http://www.youtube.com/watch?v=gKtaCFs3xcI
Understanding & Inquiring
page 264 Q’s 1 – 7
Understanding & Inquiring
page 264 Q’s 8 – 9, 12


* INVESTIGATE – Research the fuels used in rockets and explain their reactions, usefulness and dangers. Present your findings to the class

6
8.7 A New Breed of Materials
8.14 Putting fibres to the test page 266
Understanding & Inquiring
page 268 Q’s 1 – 12
Understanding & Inquiring
page 268 Q’s 13 - 21


* IMAGINE – page 268 do Question 22 (check out Jacplus Searchlight ID:eles-0859)
* RECYCLING – page 272 do Question 13

7
Revision & Test
AssessOn Ch 8 Progress and Topic Test and written test.





Class notes

type of physical properties

maleability
ductility
elasticity
opacity - transparent, opaque, translucent, reflective
colour
shiny or dull
size
shape
texture
hard or soft
squishy
solid liquid or gas

Candle observations

1.






Rates of reaction

Expt 8.7
Aim: To observe the effect of temperature on a reaction
Method
1. observe the reaction between HCl and Marble chip . Record your observation in the results table
2.gently heat the testtube containing acid and marble chip. observe and record results

Results
Observation table
Step 1
Acid and marble chip at room temp
I observed

on a scale of 1 to 5 this reaction was a
Step 2
Acid and marble chip at a higher temp
I observed

on scale of 1 to 5 this reaction was a



Discussion
Complete the questions
1. what indicated that a reaction was occurring?

2. how did this indication change when you heated the solution?

3. how does heat affect the rate of the reaction

Conclusion:









Effect of temperature.
Increasing the temperature increases the rate of reaction because the particles involved in the reaction are moving faster and bump into each other more often. This speeds up the reaction

Effect of concentration
Increasing the concentration increases the amount of particles in the slution available to take part in the reaction . so the reaction rate increases

Effect of surface area
By increasing the surface area - having a powder instead of a lump this increases the amount of places the reaction can take place. This increases the reaction rate.

complete question 1 to 9 p273

Rusting

Rusting is a form of combustion. This is where oxygen and water combine with iron. This is a slow reaction that may take 100 years to complete.
Rust Investigation 8.9
Set up the equipment and draw a clear well labelled diagram to describe the apparatus used in this investigation.
Diagram
See board
Results
After 4 days the rusting looked like this
Diagram




After 6 days (wednesday lesson) the rusting looked like this and the water level was here.
(leave some space to do this diagram)

Conclusion
(leave 4 lines for some writing and a chemical equation)
Oxygen gas in the air inside the beaker has been converted to rust and has moved out of the air in the beaker. This means the water level inside the beaker has risen ( because oxygen has been taken out).

Combustion Reactions

Combustion reactions Are reactions where things are burnt in oxygen. We give them a special name - oxidation reactions. When an element combines with oxygen we say it has been oxidised. This can happen quickly or slowly.

An example of a slow oxidation reaction is rusting - here oxygen combines with iron to form iron oxide.

An example of a fast oxidation reaction is burning gas to heat water on the stove. Here we are burning propane to form carbon dioxide and water.

A general equation for this reaction is
(fossil fuel containing carbon) Fuel + oxygen ---> carbon dioxide and water

  1. What is a fossil fuel? List three examples of fossil fuels- Remains of past living organism - eg coal , gas , oil
  2. List and describe three examples of useful oxidation reactions. - fuel, , heating, decomposition of food,
  3. Write a word equation for each of the three examples listed in question petrol + oxygen ----> water + carbon dioxide + heat
Fruit + oxygen -----> water and Carbon dioxide
wood + oxygen ----> water + carbon dioxide











Questions 1 to 8 p 276

A new breed of materials

Plastics are synthetic ie they are manufactured and do not occur naturally. Plastics have only been around for 100 years. They are the product of combining C, H, O as molecules in a repeating pattern

Fibres
Natural fibres are found in nature. Egs. linen from flax plants, cotton, wool, silk from silk worms. We often spin these fibres to produce a regular thickness as a thread that can then be woven.

Synthetic fibres are useful because they long lasting, easy care, light, hold their colour. Egs include polyester, nylon, spandex. These fabrics are made by heating the plastic and pushing it through a spinneret to make a thread. it is then woven to make the fabric.

Blended fabrics are made of a combination of natural fibres and synthetic fibres to make a fabric with the properties we want. an eg is spandex combined with cotton and polyester to make leggings/skins.

Soaps and detergents
these are chemical that are used for cleaning - they dissolve grease
They have the physical properties of feeling slippery, solids or liquids , can be colourful
They have the chemical properties of ; dissolve grease, biodegradable,

Physical properties - we use our senses to detect these (hard, soft, smell, colour, slippery etc)
Chemical properties - the thing the chemical can do- the way it reacts with other chemicals- ( acids are sour and corrosive) (Metals react with acids to produce hydrogen gas)

PLastics as packaging
  • Is the packaging recyclable? - can be remelted and turned into another product eg cup
  • Is the packaging biodegradable? - it is broken down by nature - sunlight, oxygen, weak acidic water













Designing an experiment to investigate corrosion in different metals and under different conditions

1. the variables are - air, water, salt water, acid,
2. the control is oil

If a metal corrodes I would expect to see_colour change, going dull no longer shiny _
I would see a difference if I compared this metal to a piece of the same metal that is not exposed to the variable ; air, water, sea water, ___

Draw a diagram of the set up - label all the parts


How will you record your observations?





Solutions







air
air
water
water
salt water
salt water
acid
acid
oil
oil
Metal
today..DAY 0..
next weekDAY 8

today..DAY 0..
next weekDAY 8

today..DAY 0..
next weekDAY 8

today..DAY 0..
next weekDAY 8

today..DAY 0..
next weekDAY 8

copper

y - not as shiny

nc

y cloudy

dissolved

nc
zinc

y - parts were not as shiny

y, cloudy

y white

y

nc
iron

y - rusted

y, rusty

y cloudy/rusty

y

nc
Magnesium
nc
y - not as shiny gets dull

y cloudy and broken

y broken and sediment
bubbles
y

nc


Design an experiment to identify which substance gives out the most heat when it is burnt.


the variables are:
the things we will make sure are the same between all the substances we test are
are
the control is

The equipment will be set up like this (diagram 5 lines high)






To measure the heat given off we will .....measure the increase in temperature of 5 mLs of water

Results Table
Fuel
mass of fuel
mass of fuel after burning
mass of fuel that was burnt
starting temp of the 5mLs of water
temp of water after the fuel has gone out
Total increase of temperature
paper






tissue






stick






substance x
1.2g
0.5g
0.7g
18 C
28 c
10 C
substance y
3.4g
3.1g
0.3
20 C
23 C
3 C








hmwk ques 1 and 2 p 278
Final results

Fuel
temp increase per gram
paper

tissue

stick

substance X
14.4 / g
Substance Y
10 C/g

3 / 0.3 = 10 C/g


Find three more fuels that you predict are the best fuels -that is highest temperature per gram
What do they use as fuel in africa or qatar