This lesson has been put together for year 10 Chemists during their return to school before the summer.
Purposes of these activities:
This is not new content, however, it is a recap of the work set during the lockdown and a chance to go through it with your teacher in the room. Before and after each quiz, you will get a chance to discuss this and find out things that you perhaps did not understand fully.
Rates of reactions –
Collision theory – for a chemical reaction to occur, reactant particles must collide with enough energy for them to react. The more often they collide and the more energy that they have – the faster the reaction.
To start with, open this document: we will refer to it throughout this lesson.
Effect of temperature:
If we heat up the reactants, they will have more energy so will move faster. This is like a room full of blindfolded students, if they walk around slowly, they will bump into each other but if they run, they will collide more frequently and with more energy. (We will not try this, especially as keeping 2m apart while blindfolded is not going to happen).
Effect of concentration:
Following on from the last point, if we put many more students into the same room, there will be more collisions per second which will mean a faster reaction. This is the same as increasing the pressure of a gas as it will push the particles closer together.
Effect of surface area:
By grinding up solid reactants into a powder, more of these reactants are now able to collide with the gases, liquids or solutions. The best ways to visualise this is sugar and a stick of rock are almost identical substances but if you put a spoonful of sugar into a cup of tea or the same mass of rock in, the sugar dissolves much faster. I prefer the comparison between setting fire to a pencil and setting fire to pencil shavings. The shavings burn much faster because the oxygen molecules can get to more of the carbon locked into the wood. More reactants can collide so a faster reaction happens.
Effect of a catalyst;
A catalyst is a substance that speeds up a reaction without getting used up itself. At catalyst will only work for a specific reaction and will be useless in others. It works by lowering the activation energy so a reaction can happen at a lower temperature.
Rates of reactions quiz
How well do you understand this topic?
Topic 2: Organic Chemistry
In this topic, we need to know how crude oil is formed, how we separate it into its fractions and wheat we use those fractions for.
How is crude oil formed?
The important part to remember is that the crude oil and gas from the soft squidgy bits of animals and plants. Shells make limestone. Crude oil is being formed now but it takes millions of years of heat and pressure before it is useful to us. The third picture shows drilling through rocks but in the UK, we are more used to those rocks being under the North Sea so the drills are on oil rigs.
Separation of crude oil
The process of fractional distillation is perhaps the most important process in modern chemistry. Basically, we heat the crude oil until it is mainly a vapour. It rises through the column, which is getting cooler as you rise, until you reach a point where it is cool enough to condense back into a liquid. When that happens it is collected. Look at the diagram carefully, you need to know the order of the fractions collected, their uses and, on the left, the patterns in their properties.
The alkanes are named by their size, you need to learn the first 4.
Complete and incomplete combustion. Modern life styles would not exist without complete combustion and life can be ended by incomplete combustion.
In COMPLETE COMBUSTION, hydrocarbons burn in an excess of oxygen to produce water and carbon dioxide only.
If there is not enough oxygen then INCOMPLETE COMBUSTION occurs and this is when we produce either carbon (in the form of soot) and CARBON MONOXIDE. Carbon Monoxide is known as the silent killer, it can be produced at home in gas appliances if they have not been properly installed, maintained or serviced. If you see soot forming around a boiler, get it checked. Carbon monoxide is odourless, colourless and tasteless but deadly.
This is a quick look through the things that you should have looked through during lockdown on the topic of Organic Chemistry
It is very important that you see that this is a very very short summary of what would have been covered if it was not for the school being forced to close due to the coronavirus. Please use this as a starting point and make sure that you read through the revision guides on the shared area and any that you may have purchased. Look on BBC bitesize as well as Seneca learning.