WorksheetsPRESERVATION OF METALS (Activity 1.1)
Total questions: 65
Worksheet time: 33mins
Builders in coastal regions mainly use wooden window frames instead of steel frames for homes because:
wood is less likely to corrode in salty air than steel
wood is cheaper than steel everywhere
steel is more attractive than wood
wood is heavier than steel
Corrosion is the gradual destruction of metals by chemical reactions with their environment. Why does motorbike B, which is located in Durban, show more signs of corrosion than motorbike A from Pietermaritzburg?
Durban is closer to the sea, so the salty air causes more corrosion.
Pietermaritzburg has more rainfall, causing more corrosion.
Motorbike B is older than motorbike A, causing more corrosion.
Durban has less pollution, causing more corrosion.
Painting can reduce corrosion by:
Providing a protective barrier that prevents moisture and air from reaching the metal surface.
Increasing the rate of oxidation on the metal surface.
Allowing more water to come into contact with the metal.
Reacting chemically with the metal to produce rust faster.
Galvanising is a process used to:
coat iron or steel with a layer of zinc to prevent rusting
paint metal surfaces for decoration
increase the weight of metal objects
remove impurities from metals
Describe in your own words what you observed during the experiment.
The rusted key once again has a copper colour.
The key dissolved completely in the solution.
The key turned into a silver color.
The key broke into two pieces.
Explain in your own words why, what you observed, happened.
An electrochemical reaction took place. With the use of an electric current one metal (the key) was covered with a thin layer of another metal (copper). The appearance of the key was improved and its use was prolonged.
The key was simply cleaned with water, which made it look shiny and new.
The key was heated, causing the metal to melt and form a new layer.
The key was painted with copper-colored paint to improve its appearance.
Your mother packs you cheese sandwiches for break. You forget the sandwiches in your bag and only discover them 10 days later. Describe the smell and appearance of the sandwiches as well as the reason why they look and smell the way they do.
The sandwiches and cheese have a black-brownish colour and smell awful. The colour and smell are as a result of the mould that started growing on it. The reason why the mould started growing on the bread and cheese is because the parcel in which the sandwich was wrapped became warm and moist in the school bag. Due to the heat and moist the mould grew even faster.
The sandwiches and cheese remain fresh and smell pleasant because the bag was airtight and cool.
The sandwiches and cheese turn dry and hard but do not change colour or smell because cheese preserves itself.
The sandwiches and cheese become watery and sweet-smelling due to the sugar content in the bread.
Name at least three precautionary measures to be considered when grain is stored and also explain the importance of each.
Grain must be kept dry because grain that becomes wet creates a favourable environment for fungi (funguses) and bacteria to grow. Grain must be kept at a constantly cool temperature since changes in temperature (increase in temperature) results in fungi (funguses) and bacteria growing even faster. Grain must be protected against insects, birds and rodents because they can damage it and spread diseases that can destroy the grain.
Grain should be stored in open containers to allow maximum air exposure, which helps in natural drying. Grain should be mixed with water occasionally to prevent it from becoming too dry. Grain should be left uncovered to allow birds to help in cleaning it.
Grain must be stored in direct sunlight to keep it warm and prevent any cooling. Grain should be kept moist to avoid it from drying out. Grain should be stored together with fruits to enhance its flavor.
Grain should be stored in plastic bags without ventilation to keep out all air. Grain should be kept near chemicals to prevent pests. Grain should be stored in a humid environment to maintain its texture.
Which of the following is an example of a preserved product you might find in a supermarket?
Canned beans
Fresh apples
Raw chicken breast
Unprocessed lettuce
Which of the following lists contains three different pickled products and the chemicals commonly used for their preservation?
Cucumber (vinegar), Olives (brine), Kimchi (salt)
Apple (citric acid), Banana (sugar), Grape (ascorbic acid)
Bread (yeast), Cheese (rennet), Milk (lactose)
Potato (starch), Rice (water), Corn (oil)
Fill in the blank: The ingredients in Creamy sweet corn are _________.
Water, mealies, sugar cane, salt
Milk, rice, honey, pepper
Corn, butter, cheese, garlic
Flour, eggs, vanilla, cinnamon
Fill in the blank: The ingredients in Peach slices in syrup are _________.
Peaches, water, sugar, acid regulator
Peaches, milk, honey, salt
Peaches, vinegar, oil, pepper
Peaches, water, salt, lemon
Fill in the blank: The ingredients in Pilchards in tomato sauce are _________.
Pilchards (fish), water, tomato puree, tapioca, salt
Pilchards (fish), water, cream, sugar
Pilchards (fish), tomato puree, vinegar, pepper
Pilchards (fish), water, tomato puree, garlic, onion
Fill in the blank: The ingredients in Mixed vegetables in salty water (brine) are _________.
Water, carrots, potatoes, peas, white beans, salt, sugar
Water, tomatoes, spinach, corn, salt, vinegar
Water, green beans, chickpeas, salt, honey
Water, carrots, peas, lentils, salt, pepper
Fill in the blank: The ingredients in Shredded tuna in brine are _________.
Tuna (fish), water, salt
Tuna, sugar, vinegar
Tuna, oil, pepper
Tuna, tomato sauce, garlic
Fill in the blank: The chemical used for preservation in Pickled onions is _________.
Vinegar
Salt
Sugar
Citric acid
Fill in the blank: The chemical used for preservation in Pickled cucumbers is _________.
Vinegar
Salt
Sugar
Citric acid
Fill in the blank: The chemical used for preservation in Pickles olives is _________.
Salty water (brine)
Vinegar
Sugar syrup
Lemon juice
According to the instructions for Activity 2.3: Salting and Drying of Food, which of the following items is NOT listed as a required material for the group activity?
Wax paper
Oven
Apple
Tray
Vegetable knife
Fill in the blank: The thinner the apple rings are cut, the ______ they will dry.
quicker
slower
softer
darker
If the apple rings are cut too thin, they will lose their taste.
True
False
Fill in the blank: If the days are very hot while the apple rings are drying, they may be dry enough within ______ days.
two
five
seven
ten
Use the kitchen scale to determine the weight of the apple. The weight of the apple is _______.
135g
80g
200g
50g
Taste the cut apple rings and describe the taste. The apple rings taste _______.
sweet
sour
bitter
salty
Describe the appearance of the apple.
The apple rings are moist. The apple rings start showing a change in colour.
The apple rings are completely dry and brittle.
The apple rings are covered in mold.
The apple rings are frozen solid.
Taste the apple rings that have been dried for five minutes. Describe the taste. The apple rings taste _______ than the freshly cut apple rings.
less sweet
sweeter
saltier
spicier
Use the kitchen scale to determine the weight of the dried apple rings. The apple rings now weigh _______.
100g
50g
200g
300g
Describe the appearance of the apple rings that have been dried for five minutes.
The apple rings are not as moist. Their colour has changed slightly and it looks as if the sides are starting to curl up.
The apple rings are completely burnt and blackened.
The apple rings have turned into a liquid form.
The apple rings are frozen solid and covered in ice.
Taste the dry apple rings. Describe the taste. The apple rings taste _______.
not as sweet as before. There is only a hint of sweetness.
very sour and tangy.
extremely salty and spicy.
just like fresh apples, very juicy and sweet.
Use the kitchen scale to determine the weight of the dry apple rings. The dry apple rings now weigh _______.
65g
120g
35g
90g
Describe the appearance of the dry apple rings.
The apple rings look and feel thinner and dryer. They are now light brown in colour. The apple rings look more curled up and they are dry.
The apple rings are bright green and very juicy. They are thick and soft to touch.
The apple rings are covered in sugar and look shiny. They are sticky and wet.
The apple rings are blue in colour and have a smooth, rubbery texture.
The change in taste of the apple rings during the drying process can be described as:
The taste becomes sweeter as water is removed.
The taste becomes more sour as water is removed.
The taste remains exactly the same as before drying.
The taste becomes bitter due to drying.
The change in weight of the apple rings during the drying process can be described as:
The weight of the apple rings decreases as they lose water.
The weight of the apple rings increases as they absorb moisture.
The weight of the apple rings remains the same throughout the process.
The weight of the apple rings fluctuates randomly.
The change in appearance of the apple rings during the drying process can be described as:
The apple rings become shriveled and lose moisture.
The apple rings become larger and more hydrated.
The apple rings turn into a liquid form.
The apple rings remain unchanged in appearance.
What conclusion can you draw with regard to the nutritional value of the dry apple rings?
Dry apple rings are a good source of fiber and vitamins.
Dry apple rings contain no nutrients at all.
Dry apple rings are high in unhealthy fats.
Dry apple rings are mostly made of protein.
Explain the difference between thermoplastics and thermosetting plastics.
Thermoplastic material can be softened repeatedly by heat and harden when cooled down again, without any chemical change in its composition. Thermosetting plastic material cannot be softened again by heat. When it is heated to a very high temperature it will eventually carbonise.
Thermoplastic material cannot be softened by heat, while thermosetting plastic can be reshaped multiple times by heating.
Thermoplastic and thermosetting plastics both can be softened and reshaped repeatedly by heat without any change in their properties.
Thermosetting plastics can be melted and remoulded several times, while thermoplastics cannot be reshaped once set.
1.2 Explain why a water bottle is specifically made of thermoplastic, while thermosetting plastic is used to manufacture a light switch.
Once used, the water bottle can be recycled as it is made of thermoplastic. The light switch is exposed to heat and is therefore made of thermosetting plastic so that it does not soften when heated. In addition, the light switch must be resistant to heat, scratches and prolonged use.
Water bottles are made of thermosetting plastic because they need to be strong, while light switches are made of thermoplastic so they can be recycled.
Water bottles are made of thermosetting plastic because they are exposed to heat, while light switches are made of thermoplastic because they are used frequently.
Water bottles are made of thermoplastic because they must not conduct electricity, while light switches are made of thermosetting plastic because they are transparent.
Explain why expanded polystyrene will be used specifically as packaging material to transport a freezer from the manufacturer to the retailer.
Expanded polystyrene is strong, stable and lightweight. It serves as the ideal protection for a freezer when transported. Therefore, a freezer is wrapped in polystyrene.
Expanded polystyrene is a good conductor of electricity and helps keep the freezer running during transport.
Expanded polystyrene is used because it is edible and can be consumed after unpacking the freezer.
Expanded polystyrene is used because it reacts with moisture to clean the freezer during transport.
Complete the table by indicating with a tick if thermoplastics or thermosetting plastics will be used in the manufacture of the following products:
Hamburger packaging for takeaways
The handle of a frying pan
Electric wall socket
Shopping bags used in grocery shops
Name three products in your home with the recycling symbol or request to recycle on them.
1. Plastic bottle with peanut butter. 2. Label of a Coke bottle. 3. Plastic wrapping of an egg container.
1. Wooden chair, glass window, metal spoon.
1. Cotton shirt, woolen sweater, leather belt.
1. Ceramic mug, silk scarf, rubber band.
1. Stone statue, wooden table, glass vase.
The recycling symbol or request on the products' packaging refers to which type of category? (Refer to the images labeled 1, 5, and Z.)
Type of recyclable material
Brand name
Manufacturing date
Product price
Plastic can pollute the environment in several ways. Which of the following is an example of how plastic pollution affects the environment?
Plastic waste can harm animals that mistake it for food.
Plastic helps plants grow faster in polluted soil.
Plastic increases the oxygen level in water bodies.
Plastic naturally decomposes quickly in the environment.
An example of how plastic products can be reused is:
Using a plastic bottle as a plant pot
Throwing plastic bags in the trash
Burning plastic containers
Burying plastic bottles in the ground
The recycling of plastics means:
Reusing plastic materials to make new products
Burning plastics to generate energy
Burying plastics in landfills
Throwing plastics into the ocean
Match the plastic identification code with the correct example product:
Other
Sauce packaging
PET (Polyethylene Terephthalate)
Peanut butter
HDPE (High Density Polyethylene)
Hot chocolate container with lid
PVC (Polyvinyl Chloride)
Garden hose
Which plastic identification code is used for sauce packaging?
1 PET (Polyethylene Terephthalate)
2 HDPE (High Density Polyethylene)
3 PVC (Polyvinyl Chloride)
7 (Other)
Which product is an example of 1 PET (Polyethylene Terephthalate)?
Sauce packaging
Peanut butter
Hot chocolate container with lid
Garden hose
What is the plastic identification code for a hot chocolate container with lid?
1 PET (Polyethylene Terephthalate)
2 HDPE (High Density Polyethylene)
3 PVC (Polyvinyl Chloride)
7 (Other)
Which product is made from 3 PVC (Polyvinyl Chloride)?
Sauce packaging
Peanut butter
Hot chocolate container with lid
Garden hose
Look at the image of the Instant coffee tin. What type of plastic is used for this packaging?
LDPE (Low Density Polyethylene)
PP (Polypropylene)
PS (Polystyrene)
Other
Look at the image of the Margarine container. What type of plastic is used for this packaging?
LDPE (Low Density Polyethylene)
PP (Polypropylene)
PS (Polystyrene)
Other
Look at the image of the Polystyrene meat packaging in supermarkets. What type of plastic is used for this packaging?
LDPE (Low Density Polyethylene)
PP (Polypropylene)
PS (Polystyrene)
Other
What type of plastic is used for this packaging?
LDPE (Low Density Polyethylene)
PP (Polypropylene)
PS (Polystyrene)
Other
A systems diagram of the plastic reducing project at your school should show the process from collecting Coca-Cola bottles to processing them into what final product?
Pellets
New bottles
Plastic bags
Liquid Coca-Cola
What is the first step in the Coca-Cola plastic bottle recycling process?
Bottles are transported to the recycling centre in strips.
Bottles are melted into liquid plastic.
Labels are removed from the bottles.
Bottles are filled with new drinks.
In the Coca-Cola plastic bottle recycling process, bottles are sorted according to plastic type. What type is used for bottles and what type is used for caps and labels?
Type 1 (PET) for bottles, Type 5 (PP) for caps and labels.
Type 2 (HDPE) for bottles, Type 4 (LDPE) for caps and labels.
Type 3 (PVC) for bottles, Type 6 (PS) for caps and labels.
Type 4 (LDPE) for bottles, Type 2 (HDPE) for caps and labels.
What happens to the bottle strips, caps, and labels after they are placed in water in the recycling process?
Caps and labels float to the top. Bottle strips sink.
Caps and labels sink. Bottle strips float.
All parts dissolve in water.
Caps, labels, and bottle strips all float.
What is done to the caps and labels after they float to the top in the recycling process?
Caps and labels are scooped off.
They are melted with the bottles.
They are sent to landfill immediately.
They are compressed into blocks.
What is the purpose of cleaning bottle strips in a solution during the recycling process?
To remove glue and chemicals.
To add color to the strips.
To make the strips heavier.
To melt the strips.
After cleaning, what happens to the bottle strips in the recycling process?
Bottle strips are placed into large dryers to remove all moist. Dry strips and flakes are processed to pellets.
Bottle strips are immediately sent to landfill after cleaning.
Bottle strips are colored and used as packaging material without further processing.
Bottle strips are melted and blown into glass bottles.
What is the final step in the Coca-Cola plastic bottle recycling process?
Pellets are processed to new plastic products at manufacturing companies.
Bottles are filled with new beverages.
Labels are removed from the bottles.
Caps are separated from the bottles.
The next Type 1 PET plastic product is used for the manufacture of the new project next to it because:
It is easily recyclable and can be remolded into new products.
It is biodegradable and decomposes quickly.
It is the cheapest plastic available.
It is stronger than all other plastics.
...... recycled to ..... (Refer to the images of PET plastic bottles and magnetic stripes for bank and smartcards.)
Bottles recycled to magnetic stripes for bank and smartcards.
Bottles recycled to paper bags for groceries.
Bottles recycled to wooden furniture for homes.
Bottles recycled to ceramic tiles for flooring.
Which of the following is an advantage of using more plastic during the manufacture of motor vehicles?
It reduces the overall weight of the vehicle, improving fuel efficiency.
It increases the cost of production significantly.
It makes vehicles less durable and more prone to damage.
It decreases the recyclability of the vehicle.
Select the part that is commonly made of plastic during the manufacture of motor vehicles.
Dashboard
Engine block
Tires
Windshield
