chem 2 - using resources Flashcards
(28 cards)
which polyester melts when heated vs polyester which does not melt when heated
it is thermosoftening, meaning it has no cross links between the polymer chain
thermosetting, and have strong cross links between polymer chains which don’t melt when heated
what are four properties of ceramics
low flexibilty and electrical conductivity
high melting point
no reaction with water
how to do the experiment with nail in three conditions. one with only air, one with oxygen and water and one thats only wet
- place one nail into each test tube
- in test tube 1, add a spatula of drying agent and seal with a stopper
- in test tube 2, partially submerge the nail in water and then add a stopper
- in test tube 3, submerge the nail with water, add a layer of oil on top then seal with a stopper
- leave for a week and then observe any changes
what does a drying agent do
removes moisture from the air
why is extracting copper by recycling better than extracting it from a copper ore (4)
- recycling conserves copper ores (finite resource)
- recycling uses less energy
- recycling reduces use of landfills
- recycling reduces the need for mining which causes environmental impacts
what is the process of phytomining (4)
- grow plant on land containing copper ores
- plants (which absorbed the metal compounds through roots) are harvested then burned, ash produced
- ash dissolved in acid (producing a solution of a copper compound)
- electrolysis of solution or displacement reactions to obtain the copper
what are 4 products of agriculture (farming)
cotton, wheat, timber, biofuels
what does sustainable development mean
meeting the resource needs of the current gen without compromising the future gen
why are methods like phytomining and bioleaching better than traditional mining for copper
uses less energy and are less polluting
what are the 4 stages of a products life
- extracting and processing raw materials
- manufacturing and packaging
- use and operation
- disposal
why are LCAs not the best to use
what do companies do
they may be subjective and bias
some companies take advantage of the fact LCAs are subjective and only look at aspects of LCAs that look positive - makes it seem better for environment than it actually is
what 2 ways are raw materials often extracted from the ground
mining and quarrying
how to reduce energy, waste and negative impact of products on the environment (3)
- use fewer products
- reuse old products
- recycle products
how is soda-lime glass made
by heating a mixture of sodium carbonate, limestone, and sand
explain why HDPE has a higher density than LDPE
(high/ low density poly(thene))
HDPE molecules are closer together so more atoms per unit volume
what is a composite
fibres or a material (known as reinforcement) are surrounded by a matrix acting as a binder
what is a ceramic
a non metal solid with a high melting point, that aren’t made from carbon- based compounds
what is borosilicate glass and why is it different from soda-lime glass (3)
heating boron trioxide and sand together
it has a higher melting point than soda-lime glass
used for beakers
describe thermosoftening polymers
- polymer chains with weak intermolecular forces between the chains
- little energy reqiured to melt
- can be heated then reshaped
describe thermosetting polymers
- have cross-links between polymer chains, made from strong covalent bonds
- so require lots of energy to melt them
- cannot be reshaped
name 4 alloys and what 3 of them are made from
bronze = copper + tin
brass = copper + zinc
gold alloys = zinc, copper, silver all used to harden gold
aluminium alloys
steel is an alloy of iron and another metal
what are the 3 types of steel and their uses
low carbon steel (car bodies)
high carbon steel (bridges)
stainless steel, chromium added or nickel (cutlery)
name 4 composites
- fibreglass
- carbon fibre
- concrete
- wood
whats the equation for rust
iron + oxygen + water -> hydrated iron (III) oxide (rust)
