C6 Chemistry Out There

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Why do electrolytes need to be molten?
So that the ions are free to move.
1 of 40
What are three advantages of using a fuel cell in space?
They are lightweight, they are compact, they have no moving parts and the water produced can be used by the astronauts.
2 of 40
What are two pollution problems when using fuel cells?
Fuel cells often use poisonous catalysts that have to be disposed of. Production of the hydrogen and oxygen will involve the use of energy which may have come from burning fossil fuels.
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What is an endothermic reaction?
A reaction where energy is taken in from reactants to products.
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What is the word equation for the reaction of rusting iron?
iron + water + oxygen -> hydrated iron (III) oxide
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What two types of reaction are involved in a redox reaction?
Reduction and Oxidation
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How can iron be protected by galvanising?
Galvanising is when zinc acts as a barrier and corrodes instead of iron (sacrificial metal)
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How can iron be protected by sacrificial protection?
A more reactive metal is attached to the iron, which corrodes instead of the iron as it loses electrons in preference to iron
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What is the word equation for the fermentation of glucose?
glucose -> carbon dioxide + ethanol
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How is the process of fermentation carried out?
Glucose solution is fermented in a reaction catalysed by enzymes in yeast in the absence of oxygen
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Why does there need to be an optimum temperature for fermentation?
If the temperature is too low, the yeast is inactive. If the temperature is too high, the enzyme in yeast is denatured.
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Why must no air be present during fermentation?
It prevents the formation of ethanoic acid.
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What is the balanced symbol equation for the fermentation of glucose?
C6H12O6 -> 2C2H5OH + 2CO2
13 of 40
Ethanol can be made by the reaction of ethene and water. What catalyst is used?
Hot phosphoric acid
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What is the balanced symbol equation for the reaction between hydrogen and oxygen in a fuel cell?
2H2 + O2 -> 2H2O
15 of 40
Explain how ozone absorbs important radiation in the stratosphere
The UV part of the electromagnetic spectrum has exactly the right frequency to make ozone molecules vibrate. The energy of the UV radiation is converted into movement energy inside each molecule.
16 of 40
A layer of ozone in the stratosphere can be depleted by CFC's. When UV light acts on the CFC, a highly reactive atom is made that destroys the ozone. Which atom and what type of atom is it?
Chlorine and it is a radical
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Explain how a covalent bond breaks to form a highly reactive chlorine atom
It is split into equal halves to form chlorine radical.
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UV radiation causes radicals. Each radical sets off a chain reaction. What are the three stages of the reaction?
1) UV lights breaks a bond in CFC molecules to form chlorine radicals. 2) Chlorine radicals react with ozone molecules, creating more chlorine molecules. 3)One possible termination reaction is Cl + Cl->Cl2
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How is permanent hardness produced?
When calcium sulfate rock dissolves.
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How is hard water formed?
When rainwater dissolves some of the rock that it flows over.
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Heating removes the ___ ___ __ from the water, by changing then into ____ ____ ____.
Soluble Calcium ions; insoluble calcium carbonate
22 of 40
Thermal decomposition softens ____ hardness only. Washing soda can soften both ____ and ____ had water. It is sodium carbonate.
Temporary; temporary and permanent.
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Rain water dissolves carbon dioxide. How does it change the rainwater?
Makes it slightly acidic
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Which chemical compound causes temporary hardness?
Calcium Hydrocarbonate
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Which chemical compound causes permanent hardness?
Calcium sulfate.
26 of 40
Describe how boiling removes temporary hardness
Boiling coverts calcium hydrogencarbonate to calcium carbonate, which is insoluble and removes the calcium ions
27 of 40
Describe how washing soda (sodium carbonate) can soften water
When washing soda dissolves it reacts with the calcium sulfate in the water to form insoluble calcium carbonate, so 'locking up' the calcium ions
28 of 40
Describe how ion exchange resin can soften water
The water flows over beads of solid ion-exchange resin, which trap the calcium ions on their surface, exchanging them for sodium ions instead
29 of 40
Oils and fats belong to one group of chemical compounds. What group is this called?
Esters
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When soap is made a chemical splits the oil making glycerol as well. Which chemical is used and what is the process called?
Sodium Hydroxide + Saponification
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What is Saponification?
Process of making soap from fat and sodium hydroxide.
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Fat + Sodium hydroxide -> Soap + Glycerol. What type of reaction is this process?
Hydrolysis reaction
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Why are unsaturated fats healthier than saturated fats as part of our diet?
People whose diet is rich in unsaturated oils usually have lower cholesterol in the blood; high levels of cholesterol have been linked with an increase of risk of heart disease.
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Detergents are used to clean grease and oil. Describe a detergent molecule.
A hydrophilic head and a hydrophobic tail
35 of 40
Explain how dry cleaning works
There are weak intermolecular forces between molecules of grease. There are weak forces between solvent molecules. Solvent molecules form intermolecular forces with molecules of grease and so solvent molecules can surround molecules of grease.
36 of 40
_____ ______, such as vegetable oil and water, form an emulsion when shaken with an emulsifier.
Immiscible liquids
37 of 40
Bromine isan orange liquid. Bromine reacts, in a ____ reaction, with the carbon-carbon double bonds in the chain. The reaction uses up the bromine molecules, making a ___ ___. This compound is colourless.
Addition; Dibromo compound
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The reaction of splitting up natural oils with alkalis is called ______.
Saponification
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What is a displacement reaction?
Chemical reaction where one element displaces or pushes out another element from a compound.
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Other cards in this set

Card 2

Front

What are three advantages of using a fuel cell in space?

Back

They are lightweight, they are compact, they have no moving parts and the water produced can be used by the astronauts.

Card 3

Front

What are two pollution problems when using fuel cells?

Back

Preview of the front of card 3

Card 4

Front

What is an endothermic reaction?

Back

Preview of the front of card 4

Card 5

Front

What is the word equation for the reaction of rusting iron?

Back

Preview of the front of card 5
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