Year 8 Science Spring Term Homework Pack

Name: _________________________Class: _________________________Teacher: ________________________Our Spring Term Homework Programme.

Due on [Friday]:Approximate Time Needed

Is there help?Where can I find it?

Week #1

Homework 1: [10th Jan] Distillation 30 minutes Goo.gl/N1NpEc

Week #2

Homework 2: [17th Jan]Oil 30 minutes Goo.gl/N1NpEc

Week #3

Homework 3: [24th Jan]Separating mixtures 30 minutes Goo.gl/N1NpEc

Week #4

Homework 4: [31st Jan]Chromatography 30 minutes Goo.gl/N1NpEc

Week #5

Homework 5: [7th Feb]Forensic evidence 30 minutes Goo.gl/N1NpEc

Week #6

Homework 6: [14th Feb]A tropical environment 30 minutes Goo.gl/N1NpEc

Week #7 -HalfTerm

Homework 7: [28th Feb]Human activities and organisms

30 minutes Goo.gl/N1NpEc

Week #8

Homework 8: [6th Mar]Chains, webs and pyramids 30 minutes Goo.gl/N1NpEc

Week #9

Homework 9: [13th Mar]The human population 30 minutes Goo.gl/N1NpEc

Week #10

Homework 10: [20th Mar]Rocky equations 30 minutes Goo.gl/N1NpEc

Week # 11

Homework 11: [27th Mar]Using salts 30 minutes Goo.gl/N1NpEc

Week #12

Homework 12: [4th Apr]Making copper sulphate 30 minutes Goo.gl/N1NpEc

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Homework #1. DUE: [10th Jan]

Distillation

Label the parts of the distillation apparatus shown below, using words from the box.

beaker flask heat Liebig condenser thermometer water in water out

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The water evaporates and forms steam. The ink does not evaporate.

The mixture is heated.

The water runs into the beaker.

The cold water flowing around the outside of the condenser cools the steam.

The mixture of ink and water is put into the flask.

The steam goes into the condenser.

The steam condenses to form pure water.

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The history of distillationWhen microbes called yeast feed on sugar one of their waste products is alcohol. This process is called fermenting. When a certain amount of alcohol has been made it poisons the yeast and they die. Beer and wine can never be stronger than about 15% alcohol, because the yeast cannot make more alcohol than this before they die.

People wanted alcoholic drinks that were stronger than beer and wine. Distillation is a way of getting the alcohol out of the mixture of alcohol, dead yeast and water.

Alcoholic drinks are usually distilled from a beer (made from a fermented grain like barley, oats or even rice) or from a wine (made from fermented grape juice). Other natural materials like potatoes and even treacle have been fermented and then distilled. If wine is distilled the product will be a brandy. If a beer is distilled the product will be a whisky.

Distillation has been used to separate a pure liquid from a mixture since 800 BC, when it is recorded that an alcoholic drink called Sochou was separated from rice which had been fermented by yeast, in Japan. The first recorded use of distillation to separate an alcoholic drink in Britain was in the sixth century (500 AD) when alcohol was separated from mead, which is made by fermenting honey. The first recorded distillation of whisky in Scotland did not occur until a thousand years later.

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For centuries, distillation has also been used to separate oils and perfumes from natural materials. These were then used as medicines and scents, forming the basis of the modern medicine and cosmetic industries.

1 What was the first alcoholic drink made from? 2 How is mead made?3 What are the main materials from which alcoholic drinks can be made?4 What is the difference between brandy and whisky?5 Why is distillation needed to make strong alcoholic drinks?6 What other chemicals have been separated using distillation?

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Homework #2. DUE: [17th Jan]

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Oil

What is in a barrel of oil?When a barrel of crude oil is distilled, the following chemicals are obtained:

Description of chemical separated Amount in barrel (percentage of barrel)Hydrocarbon gases  2%

Naphtha  4%Petrol 31%

Kerosene 11%Gas oil & Diesel oil 30%

Fuel oil 18%Lubricating oils, Waxes and Bitumen  4%

1 Use the information from the table to plot a bar chart to show the amount of each type of chemical in the barrel of oil. Label each axis and each bar on the chart. Use the bar chart to help you answer the following questions.

2 Which type of chemical is there most of in a barrel of crude oil?3 Which chemical is there least of in a barrel?4 Use the data in the table to draw a pie chart to show the amount of each type of chemical.5 Which chart would you use to explain about the parts of a barrel of oil to someone who doesn’t

know about oil? Explain why you chose this graph.6 Research: try to find out at least two uses for each fraction in a barrel of oil.

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Homework #3. DUE: [24th Jan]Separating mixtures

This particle diagram shows why filtering will separate sand from water, but will not separate dissolved salt from the water. You can use similar diagrams to explain how other ways of separating mixtures work.

1 Evaporation can be used to separate a liquid and a dissolved solid. Draw a labelled particle diagram to explain what happens when you heat a solution.

2 What is the difference between evaporation and distillation?3 Chromatography can separate different coloured particles that are dissolved in a liquid.

Chromatography works because the particles that make up different coloured substances are usually different sizes. Draw a particle diagram to show what happens in chromatography.

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Homework #4. DUE: [31st Jan]Chromatography

The chromatogram shown below is designed to see if you can analyse the results from a complex chromatogram. Look at the diagram carefully, and then answer the questions which follow. The ‘standard’ shown in the first column of the chromatogram contains all of the chemicals which are found in the ‘tested samples’. The solvent used for this experiment was water.

1 Which of the tested samples were pure (contained only one substance)?2 Which of the tested samples were mixtures (contained more than one substance)?3 Name the substances contained in sample B.4 Name the substances contained in sample D.5 Which chemical in the ‘standard’ sample is the most soluble in water?6 Which chemical in the ‘standard’ sample is the least soluble in water?7 Explain your answers to questions 5 and 6.8 Which chemicals from the ‘standard’ sample did not appear in any of the ‘tested’ samples?

Explain your answer.9 Why do some chemicals appear higher up the chromatogram than others?

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Homework #5. DUE: [7th Feb]

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Forensic evidence

In 1984, Professor Alec Jeffreys of Leicester University invented a new method to identify a suspect in police investigations. Criminals often leave hairs or sweat or blood at the scene of a crime. Cells in our bodies contain a chemical called DNA, and scientists can use a method known as ‘DNA fingerprinting’ to compare DNA from a suspect with DNA from materials left at the scene of a crime. The chemicals found at the scene of the crime could have come from the body of the suspect or they might have come from someone else who has yet to be found.

The technique can be used to identify people who were at the scene of a crime. DNA fingerprinting is a type of chromatography.

The diagram above shows the result for several suspects.

Remember that the pattern from the suspect must be the same as the pattern from the scene of the crime if the suspect was the person who left the evidence.

Look at the pattern very carefully and answer the following questions.

1 Which suspect, Person A, B or C, was the one who left the chemicals at the scene of the crime?2 What does this tell you about the other two suspects? Explain how you know this.3 Do you know who committed the crime? Explain your answer.4 Research: find out more about genetic fingerprinting and the use of chromatography to identify

chemicals found at the scene of a crime.

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Homework #6. DUE: [14th Feb]

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A tropical environment

A tropical fish tank.

Many people keep tropical fish at home in a fish tank. The environmental conditions have to be carefully controlled in order to keep the fish alive.

1 Explain what each of the following pieces of equipment is needed for:

a thermostat ____________________________________________________________

b heater ________________________________________________________________

c air pump ______________________________________________________________

d water filter ____________________________________________________________

2 Suggest two reasons why it is important to have plants in the aquarium.

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3 Imagine that you were setting up a tropical fish tank at home.a What resources would you have to provide to keep your fish alive and healthy?

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b List the names of five living organisms that you might put into your tank.

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Homework #7. DUE: [28th Feb]Human activities and organisms

Human activities can have a big effect on the environment. Unfortunately most of our activities are harmful and affect the distribution of organisms living in the environment.

Sarah wanted to investigate the effects of some human activities on the distribution of organisms in a river. Look at this drawing of the river that she investigated.

1 a How could Sarah find out which part of the river had the highest population of bacteria?b Briefly explain how she could measure the amount of dissolved oxygen in the water at

points A, B and C.c At which of these points in the river would you expect Sarah to find the lowest

concentration of dissolved oxygen in the water?d Explain your answer.

2 Alongside part of the river is a farm. The farmer uses a lot of fertiliser on his crops. After heavy rain much of this gets washed off the fields and drains into the river. What effect will this have on the population of plants growing in the river?

3 a Which point in the river do you think would be the safest place to catch fish that were going to be eaten by humans?

b Explain your answer.c At which point in the river do you think there would be the largest population of fish?d Explain your answer.

4 Estimating the size of animal populations, such as fish in a river or foxes in a wood, is much more difficult than estimating plant populations.a Explain why this is.b Find out the name of a sampling method that Sarah could use to estimate the population

of fish in the different parts of the river.

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Homework #8. DUE: [6th Mar]

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Chains, webs and pyramids

Here are three food chains:

A grass rabbit fox

B wheat field mouse fox

C wheat field mouse grass snake

1 Sketch a pyramid of numbers for food chain A.

2 Use all three food chains to draw a food web.

3 Name one producer in the food web. ____________________________________________

4 Name a primary consumer. ____________________________________________________

5 Name a secondary consumer. __________________________________________________

6 a If the field mice died, what would happen to the number of grass snakes?

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b Why would this happen?

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c If the field mice died, what might happen to the number of rabbits?

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d Why might this happen?

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Homework #9. DUE: [13th Mar]

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The human population

 1 Use the data below to draw a graph showing how the world’s human population has increased since 1500. Join the points together with a smooth curve. Leave space on the graph to continue it further (up to 2025 and 10 000 million people).

Year Estimated world population (millions)

1500  4001550  4201600  4801650  5751700  6401750  7251800  9251850 12001900 16001950 24001975 40002000 6100

 2 Most populations are kept in check by other factors (the human population is an exception). Name two factors that might keep a population of rabbits in check.

 3 Why do you think that the human population has increased so much in the last 100 years.  4 Continue your graph to estimate the number of people in the year 2025.  5 How might the growth in human population be slowed down in the future? 6 In various places around the world, there are too many people and not enough food. How does

this affect the population in these areas? 7 Wars often cause people to leave an area. This is called emigration. The same word is used for

other animal populations. What might cause foxes to emigrate? 8 People arriving in a new area is called immigration. What effects might human immigration

have on an area? 9 Why might foxes immigrate to a particular area?10 Find out about the ‘Black Death’ and how it affected the population of Britain in the 14th

century.

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Homework #10. DUE: [20th Mar]Rocky equations

Calcium carbonate is one of the most common minerals in the Earth’s crust. Rocks such as chalk, limestone and marble are all mainly made from calcium carbonate. Calcium carbonate reacts with acids to give off carbon dioxide gas.

Coral and Simon did an experiment with three different types of rock. They added the same amount of hydrochloric acid to three 10 g samples of rock. This is the apparatus that they used:

Here are their results:

Time in seconds 0 10 20 30 40 50 60 70 80volume of gas in cm3 (Rock A) 0 19 32 43 50 56 59 60 60volume of gas in cm3 (Rock B) 0  0  0  0  0  0  0  0  0volume of gas in cm3 (Rock C) 0 25 40 50 55 60 60 60 60

1 Plot these results on a piece of graph paper. Plot all three lines on the same graph. Use axes like this:

2 Which two rocks were carbonates? Explain your answer.3 How would you test for carbon dioxide gas?4 One of the rock samples was marble chips and the other was

powdered chalk. Suggest which rock was powdered chalk.

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Explain your answer.

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Homework #11. DUE: [27th Mar]

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Using salts

Salts are very useful chemicals. There are a large number of different salts which have many different uses.

Look at these labels torn off packets and use the information to answer the

questions below.

1 Name two ways that potassium nitrate can be used.2 Name three elements that plants need for healthy growth.3 a Write down two uses for copper sulphate.

b Copper sulphate can be made using a reaction between copper oxide and an acid. Which acid?

c Write a word equation for this reaction.4 a Give two reasons for adding sodium chloride (common salt) to food.

b Suggest an acid and an alkali that could be reacted together to make sodium chloride.c Write a word equation for this reaction.d What is this sort of reaction called?e What pH is a solution of sodium chloride in pure water?

5 When photographic film is exposed to light, the salt on the film breaks down. What metal do you think is formed?

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Homework #12. DUE: [4th Apr]Making copper sulphate

Copper sulphate is an example of a salt which is formed when an insoluble base reacts with an acid. This is a set of instructions for preparing copper sulphate (CuSO4) from sulphuric acid and copper oxide.

• Add small amounts of solid copper oxide powder to 25 cm3 of dilute sulphuric acid, and stir. • Keep adding powder slowly until some unreacted copper oxide remains at the bottom.• Filter the solution to remove the unreacted copper oxide and transfer the filtrate into an

evaporating basin.• Heat the contents of the evaporating basin gently until about a third of the water has

evaporated.• Leave the solution to cool and then examine the crystals which are formed.

1 Write a list of all the apparatus that would be needed to prepare copper sulphate crystals.2 What safety precautions would you need to take if you were following these instructions?3 Why was copper oxide added until some was left on the bottom of the beaker?4 Why is it better to have copper oxide powder left in the beaker after the reaction, rather than

having dilute sulphuric acid left behind?5 Why was it necessary to filter the mixture before evaporating it?6 Write word and symbol equations for the reaction that took place.7 What would the copper sulphate crystals look like?

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