Chemistry Flashcards
What is a life cycle assessment?
An analysis of the overall environmental impact that a product may have throughout its lifetime
What is distillation?
Purifying a liquid by heating and cooling
What are the two processes for obtaining copper from low-grade copper ores?
- Using bacteria in a process called bioleaching
- Using plants in a process called phytomining
What are the drawbacks of mining (Four)
- Visual pollution
- Sound pollution
- Increased traffic in the area
- Air pollution
What are the TWO methods of obtaining copper from the ore
- Using sulfuric acid to produce copper sulfate solution, before extracting copper metal via displacement
- Heating the copper ore to a high temperature in a furnace with air to produce impure copper
What are some of the general uses/needs for copper? (Three)
- Electrical wiring
- Construction
- Home appliances
What happens during final treatment of sewage (Two stages)
- In the last tank, the useful bacteria are allowed to settle out to the bottom of the tank as sediment.
- Sometimes the water is filtered through a bed of sand, and then sterilised using UV
What happens during primary treatment (sedimentation)?
The waste water is allowed to stand still in the tank. heavier solids sink to the bottom creating sewage sludge. The sludge is then removed
What happens during screening? (Sewage)
Removes large objects using a large metal grid
What is an ion?
A charged particle (can be negative or positively charged.
What are the FOUR stages of sewage treatment
- Screening
- Primary treatment - sedimentation
- Secondary treatment - aerobic digestion
- Final treatment
Process of salt water -> potable water (via Distillation)
Heated until it boils. The salt is still in the liquid but when the steam cools and condenses it is pure potable water (An expensive water)
Process of salt water -> Potable water (Via osmosis).
And why is this more efficient in terms of energy?
Uses membranes to separate the water and salts dissolved in it. The membrane can catch 98% of dissolved salts.
- No heating required so uses less energy.
What is desalination
converting salty water to potable water
What are the physical properties of Group 7 elements (Three)
- At room temperature the physical state changes as you go down the group.
- The colours change as you go down the group.
- The melting points and boiling points change as you go down the group.
What happens at the positive anode?
Negative anions lose electrons - they are oxidised
What do these do in water?
1). Iron
2). Magnesium
3). Lithium
4). Sodium
5). Potassium
1). Iron - very slow reaction - some bubbles
2). Magnesium - Slow reaction - bubbles
3). Lithium - Fast reaction - floats, fizzes
4). Very fast reaction - floats, fizzes and forms a ball
5). Instant reaction - burns with a lilac flame, moves around
What is an isotope?
Atoms of the same element with the same number of protons but DIFFERENT number of neutrons
What do the symbols at the top and the bottom of an element mean
TOP: Relative atomic mass - protons + neutrons
BOTTOM: Atomic number: no. of protons
What is chromatography?
This technique is used to separate substances that have a different solubilities
What is the method of chromatography
- Pencil line is drawn on chromatography paper and spots of different ink are put on it.
- The paper is put into a beaker of water (the pencil line sits above the level of the solvent)
- The ink will spread across the paper showing the pigments
What is an element?
A substance that is 100% pure - each element is made up of just one type of atom
What are the properties of metals and non-metals FOUR
METALS
- Higher melting & boiling points - tend to be solids at room temperature
- Silver-coloured
- Good conductors
- Malleable (can be shaped)
NON-METALS
- Lower melting and boiling points
- More likely to be colourful
- Poor conductors of heat and electricity
- Brittle (They snap/smash easily)
How is an ion made?
An ion is made when an atom loses or gains electrons to have a full outer shell of electrons
What are the properties of the alkali metals? (Three)
- Silvery-coloured metals
- They are soft and could be easily cut with a knife
- They are highly reactive
What was Ernest Rutherford’s theory?
By firing positively, charged alpha-particles at a gold sheet, he found that some passed through, while others deflected back. Rutherford had discovered the nucleus + disproved JJ Thomson.
What model did these guys discover?
1). Ernest Rutherford
2). Niels Bohr
3). John Dalton
4). JJ Thompson
1). Nuclear model
2). Nuclear model 2.0
3). Solid sphere model
4). Plum pudding model
