C1 Flashcards
Which state something is at a given temperature depends on…
how strong the forces of attraction are between the particles of the material
What is a physical change?
When substances change from one state to another- easy to reverse
What is a chemical change?
When bonds between atoms break and the atoms change places
In solids, how strong are the fores of attraction between particles and what is the effect on the structure?
There are strong forces between particles, which holds them close together in fixed positions to form a regular latice. The volume and shape is constant.
In liquids, how strong are the fores of attraction between particles and what is the effect on the structure?
There are weaker forces than in solid between particles, which allows them to move past each other, but tend to stay close together. The volume is constant but the shape is changeable.
In gases, how strong are the fores of attraction between particles and what is the effect on the structure?
There are no forces between particles, which means they are free to move and are far apart. The volume and shape are both changeable
What are the flaws to the particle theory?
- It doesn’t show different shapes / types of particles
- It doesn’t show the forces between particles, therefore therefore there is no way of telling how strong they are
What are displacement reactions?
When in a reaction, a more reactive element displaces less reactive element
Why is bond breaking an endothermic process?
Because bonds require energy to be broken
Why is bond forming an exothermic process?
Because energy is released when bonds are formed
What is the formula to work out the overall energy change in a reaction?
Overall energy change = Energy required to break bonds - Energy released by forming bonds
Describe what phase 1’s atmosphere was like and why
It was mostly CO2, due to the vast amount of volcanoes. There was also a fair bit of nitrogen and water vapour
Describe what phase 2’s atmosphere was like and why
The Earth cooled, causing the water vapour to condense and form the ocean. This then meant the masses of CO2 was also significantly reduced, as lots dissolved in the oceans
Describe what phase 3’s atmosphere was like and why
The introduction and development of plant life meant that CO2 levels dropped further, as well O2 levels began to increase- this is because of photosynthesis
What did the increasing amount of O2 in the atmosphere allow?
More complex life to be established and evolved
When do combustion reactions occur?
When you burn substances in oxygen
What is a complete combustion?
When you burn a substance in plenty of oxygen
What is the general equation for complete combustion reactions?
Fuel + Oxygen -> Carbon Dioxide + Water Vapour
What does the fuel burned in combustion reactions usually consist of?
Hydrocarbons e.g. Methane
What is incomplete combustion?
When you burn a substance in not enough oxygen
What does incomplete combustion produce?
Carbon monoxide and carbon particulates
What are the effects on carbon monoxide?
It prevent the red blood cells from transporting oxygen around the body, which can lead to fainting, a coma or even death
What are the effects of carbon particulates?
Carbon particulates (soot) can make buildings look dirty, reduces air quality and can cause/worsen respiratory problems
How is sulfur dioxide released?
In some fossil fuels, there are sulfur impurities, which when oxidised during combustion turns into sulfur dioxide
What are the effects of sulfur dioxide?
It can cause acid rain, which can kill plants, damage buildings and structures, and makes metal corrode.
Also it can cause smog to form which can cause/worsen respiratory problems
What is the pros and cons of removing sulfur impurities from fuels?
PROS-
- No longer produces sulfur dioxide which can lead to many problems
- It will discourage the mass use of fossil fuels (as it will be more expensive) which lead to many problems
CONS-
- It is expensive
- It takes a lot of energy, which will likely be produced from fossil fuels
What is the test for chlorine?
Chlorine will turn blue litmus paper white
What is the test for oxygen?
A test tube of oxygen will relight a glowing splint
What is the test for carbon dioxide?
Mixing carbon dioxide and an aqueous solution of calcium hydroxide will cause the solution to turn cloudy
What is the test for hydrogen?
When a lit splint enters a test tube of hydrogen it will make a loud squeaky pop
What is a fuel cell?
An electrical cell that uses the energy from the reaction between oxygen and a fuel.
What is the most common fuel cell?
Hydrogen-Oxygen fuel cell
What does the reaction of hydrogen and water in fuel cells produce?
H2O
What are the advantages of hydrogen-oxygen fuel cells?
- No pollutants
- Less stages so less lost energy
What are the disadvantages of hydrogen-oxygen fuel cells?
- Hydrogen is a gas so hard to store
- Very explosive
- Hydrogen fuel needs energy to be produced (likely from fossil fuels)
What is ground water?
Water from aquifers (rocks that trap water underground)
What is waste water?
Water that has been contaminated by a human process e.g. sewage
What is salt water?
Water from the sea
How do you make ground water potable?
1) The water is mixed with air to increase the levels of dissolved oxygen, which forces other gases and certain ions out
2) The water is then filtered to remove any solid impurities
How do you make waste water potable?
1) The water is then filtered to remove any solid impurities
2) Air is pumped in to encourage aerobic bacteria to grow and break down any organic matter
3) Some waste water containing toxic substances, and would require additional stages such as using chemicals or UV radiation
How do you make salt water potable on a small scale?
It can be distilled using a solar still-
1) A bowl filled with salt water and covered with a clear dome lid is placed in the sun
2) The water warms up and evaporates onto the lid, and then condenses, where it can be collected and drank. The salt is left behind in the bowl
How do you make salt water potable on a large scale?
It can be distilled by the heat from burning fossil fuels
1) The container is filled with salt water
2) The container is heated by the burning of fossil fuels
3) The water evaporates, leaving the salt behind, meaning it is ready for drinking
ALTERNATIVELY
A membrane can be used as a microscopic filter, only allowing water molecules to pass through (reverse osmosis)
What is a problem with making sea water potable on a large scale?
All methods require lots of energy, making them expensive and impractical
Why is every sources final step chlorination?
Because it kills harmful bacteria and other microbes, which can spread disease
What is a risk of chlorination?
In certain conditions, chlorine can react with certain compounds to form potentially dangerous chemicals
