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What are the advantages and disadvantages of Polymers (plastics)?
Advantages:- Long lasting/durable Disadvantages:-Difficult to dispose of, takes up space in landfill, burning them releases toxic gases, using valuble resources
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What are 3 ways of disposal of plastics and what are their problems?
Landfill- It is a waste of land Burning- The plastics produces air pollution and toxic gases Recycling- prevents resources being wasted but the sorting of plastics is expensive and time-consuming
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State two ways the disposal of plastics could be improved
Dissolve- Soluble plastics can make disposal easy when incorporated into a liquid to form a solution. Photo-degradable- This means the Plastics could be broken down by light and the sun.
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What happens when a chemical change occurs?
new substances are formed from old ones, there may be a change in mass when a gas is released, often a substantial energy change e.g. rise or fall of temperature, the change cannot be reversed easily.
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What happens when you cook protein?
The protein molecules change shape when they are heated. This is called denaturing.
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What happens when you cook vegetables?
Vegetables are plants; their cells have a rigid cell wall. During cooking, the heat breaks down this cell wall, starch is released and it becomes much softer. The starch grains swell up and spread out, which makes it easier to digest.
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What happens when you heat Baking Powder and what is the equation for this?
When it is heated, it breaks down to make sodium carbonate and water, and carbon dioxide is given off. If added to a cake, CO₂ makes it rise. Sodium hydrogen-carbonate sodium carbonate + water + carbon dioxide OR 2NaHCO₃ Na₂CO₃ + H₂O + CO₂
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What is the test used to see if CO₂ is present?
Yous can do this by using limewater. If carbon dioxide is present, the limewater turns milky.
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What are additives?
A material that is put in a food to improve it in some way.
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What are the 4 additives?
Antioxidants- to stop food reacting with oxygen. Food colours- are used to improve the colour of food. Flavour enhancers- to improvethe flavour of food. Emulsifiers- help water and oil to mix and not separate.
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How do emulsifiers work?
The molecules in an emulsifier have 2 ends: The hydrophilic part which is water loving, and the hydrophobic part which is oil loving and water hating. The hydrophilicend bonds to the water molecules and the hydrophobic end bonds to the oil molecules.
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What 5 things must perfumes be able to do?
Evaporate easily, not be toxic, not irritate, not dissolve in water, not react with water.
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What 2 types of perfumes are there?
Some come from natural sources, such as plants and animals. Perfumes can also be manufactured and they are known as synthetic perfumes.
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What are Esters?
They are a common family of compounds used as synthetic perfumes. It is made by reacting an alcohol with an organic acid. This produces an ester and water.
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What does volatile mean and why are perfumes volatile?
Volatile means that a liquid evaporates easily. The molecules in perfume are held togehter by weak intermolecular forces of attraction. The molecules that escape have lots of energy and easily overcome the weak attraction to the other molecules.
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Explain what these substances are: soluble substance, insoluble substance, a solvent, the solute, a solution.
Soluble substances are substances that dissolve in a liquid. Insoluble substances are substances that don't dissolve in a liquid. The solute is the substance that gets dissolved. A solution is what you get when you mix a solvent and a solute.
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Give 2 reasons why water will not dissolve nail varnish.
The attraction between water molecules is stronger than the attraction between water molecules+particals in nail varnish, the attraction between particals in nail varnish is stronger than the attraction between water molcules+particals in nail varni
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List water, ethanol, ethyl ethanoate and propanone in the order of being most effective at removing nail varnish and sodium chloride (salt).
Nail varnish: water-doesn't dissolve, ethanol-dissolves in 15 secs, ethyl ethanoate-dissolves in 3 secs, propanone- dissolves in 2 secs. Sodium chloride: Water-very soluble, ethanol-slightly soluble, ethyl ethanoate-insoluble, propanone-insoluble.
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What is paint and what is it used for?
Paint can be used to protect or decorate a surface. It is a special mixture of materials and it is called a colloid. In a colloid, fine solid particals are well mixed with liquid particals but they are not dissolved.
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Name 3 things that paint is a mixture of.
A pigment- a substance that gives paint its colour, a binding medium-an oil that sticks the pigment to the surface, a solvent- thins the paint making it easier to spread.
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Explain what happens when paint dries.
The paint coats a surface with a thin layer and the solvent evaporates as the paint dries.
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Name 2 special pigments and what they do.
Thermochromic pigments- change colour when they are heated or cooled. Phosphorescent pigments- glow in the dark. They absorb and store energy and release it slowly as light when it is dark.
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Why must the particle size of the solids in a colloid be very small?
They must be very small so they stay scattered throughout the mixture. If the particles were too big, they would start to settle down to the bottom.
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What are the 2 stages in which an oil-based paint dries?
1)The solvent evaporates away 2)The oil-binding medium reacts with oxygen in the air as it dries to form a hard layer. This is an oxidation reaction.
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Other cards in this set

Card 2

Front

What are 3 ways of disposal of plastics and what are their problems?

Back

Landfill- It is a waste of land Burning- The plastics produces air pollution and toxic gases Recycling- prevents resources being wasted but the sorting of plastics is expensive and time-consuming

Card 3

Front

State two ways the disposal of plastics could be improved

Back

Preview of the front of card 3

Card 4

Front

What happens when a chemical change occurs?

Back

Preview of the front of card 4

Card 5

Front

What happens when you cook protein?

Back

Preview of the front of card 5
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