C6: Chemistry out there
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- Created by: Orla Knox-Macaulay
- Created on: 08-04-13 11:43
What happens in electrolysis to the anode
The negative ions move to the anode and it loses electrons
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what happend to the cathode during electrolysis
The positive ions in the electrolyte moves onto the cathode and it gains electrons
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What kind of substances decompse into elements during electrolysis
molten substances
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how can hydrogen and oxygen be formed froim solutions
the H= and OH- ions in water
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what reaction do fuel cells use to release electrical energy
its a reaction between hrdrogen and oxygen
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what is one advantage and one disadvantage to the usage of fuel cells on rockets
adv: clean and effieecient, quick disadv:
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what is a redox reaction
This is when reduction and oxidation happens at the same time
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Give one example of a redox reaction
1. iron atoms are oxidised to iron(ii) ions when they react with a dilute acid.
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What is a displacement reaction
a more reactive metal will kick out the less reactive metal
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What is reduced and oxidised in a displacement reaction
metal ions are reduced and metal atoms are oxidised
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What can be used to prevent rust
oil, grease, paint, coat of tin (protect steel), alloys(metals being combined), sacrificial metal
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What is meant by the sacrificial method
This is NOT a displacement reaction. This is whe you place a more reactive metal on top of a less reactive metal so the top layer rusts and the other one doesn't. It acts as a barrier. It's galvanising (coat of zinc on top of the object)
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What does CFC standfor?
chlorofluorocarbons
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what is the ozone layer
this is a form of oxygen, in the stratosphere. It absorbs UV light from the sun
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How are CFC's destroying the ozone layer
They make the O3 molecules into O2 molecules. This is making the ozone layer deplete
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Hopw do chlorine free radicals damage the ozone layer
Uv light makes the carbon-chlorine bonds break to form free radicals. the chlorine free radicals turns the O3 into O2 and chlorine oxide. The chlorine oxide is very reactive and this reacts with the ozone to make another set...................
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What are natures alternatives to CFC's
Alkanes- they dont react with the ozone. HFCs-this is hydrofluorocarbons they contain no chlorine, that is what reacts with the ozone.
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What can hard water make
scum and scale
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what are the properties of hard water
not easily lather, can form limescale which eventually blocks pipes in homes.
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What is hardness caused by
magnesium sulfate and calcium carbonate ( CC doesn't dissolve in water but will with acids.Since CO2 from the air dissolves in rainwater to make it slightly acidic)
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Whats the equation for the rain water reaction
carbon dioxide+water+calcium carbonate------> Calcium hydrocarbonate
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What are the two types of hardness
temporary and permanent
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How does boiling remove temporary hardness
The calcium hyrdocarbonate decomposes to form insoluble calcium carbonate.
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What can remove both types of water hardness
washing soda and ion exchange.
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What is ion exchange
sodium/hydrogen ions exchange them for calcium/magnesium ions
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What is fermentation
this is used to convert sugars (usually glucose) into ethanol. this is done by enzymes found in yeasts. The temp needs to be controlled, it's also important to make sure oxygen doesn't get in, respire anaerobically.
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What is hydartion
ethene reacts with steam to make ethanol, this reaction needs a temp of 300 celcius and a pressure of 70 atmospheres. The ethene and steam are passed over a heated phosphoric acid catalyst for industrial use.
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Where do fats and oils come from
animals and plants
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when are fats solids and oils liquid
at room temp
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why are natural fats and oils importnat for the chemical industry
because they can be used as alternatives for crude oil
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what is an emulsion
when oils and water do not mix- hydrophobic and hydrophilic heads/tails
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Give an example of an oil in water emulsion
milk
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give an example of a water in oil emulsion
butter
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how are vegetable oils used to produce bio diesel
they have alot of energy and bio diesel have similar properties to ordinary fuels so it is an alternative
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What is saponification
the process of making soap. breaks up the fats/oils to release glycerol and fatty acids, this is hydrolysis. then the acids reacts with the sodium hydroxide to then create soap
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what is the word equation for saponification?
fat+ sodium hydroxide----> soap + glycerol
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what is the difference between saturated and unsaturated fats/oils
saturated have single bonds whereas unsaturated have double bonds
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what is monounsaturated
contains one double bond somewhere in the carbon chain
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what is polyunsaturated
contains more than one double bond
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how does bromine water detect double bonds
unsaturated oils or fats will decolourise bromine water and addition reaction takes place at the double bond and a colourless dibromo compound is formed
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what is hydrogenation
unsaturated oils can be hardened by reacting them with hydrogen with a nikel catalyst at 60 celcius. this is when thr hydrogen reacts with the double bonded carbons and opens them.
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what is healthier: saturated or unsaturated
unsaturatred
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do detergents has hydrophobic head and hyrodphilic tails
NO
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how do detergents work?
the hydrophilic head makes a strong intermolecular force with the water droplets and the other way round with the tails. This helps to lift oil/dirt of frabics
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what do dry cleaners use to remove stains
solvents
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how do washing clothes at lower temps save energy
use biological detergents
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Other cards in this set
Card 2
Front
what happend to the cathode during electrolysis
Back
The positive ions in the electrolyte moves onto the cathode and it gains electrons
Card 3
Front
What kind of substances decompse into elements during electrolysis
Back
Card 4
Front
how can hydrogen and oxygen be formed froim solutions
Back
Card 5
Front
what reaction do fuel cells use to release electrical energy
Back
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