Question | Answer |
What do you call wehn chemicals join or break apart to form new chemicals? | chemical reaction |
What is a physical change? | When no new substances are formed. |
What do you call it when e.g water turns back to ice and ice turns into water? | reversible |
What do you call it when new susbstances are formed during chmeical reaction? | irreversible |
What will happen when energy is used to get the chemicals to react? | It may split up or decompose |
What happens when iron and steel meets? | It will rust |
Why are acid rain corrosive? | Because sometimes rainwater may be polluted with nitric or sulphuric acid. |
What is te proccess called when the iron reacts with oxygen and water in the air and turned into a new substance? | Iron oxide. |
What is a hydrogen gas? | It is the bubble you can see. |
How can you make dry ice? | You have to cool down the carbon dioxide down to about -80'c. |
What test do you use to see if the gas is carbon dioxide? and how? | We test by limewater and if carbon dioxide is mixed with limewate, it'll go milky. |
What is electrical detonators for? | To set off the fireworks for displaying. |
How many things are needed to burn a fire and what are they? | a substance that burns(fuel),energy to start the fire(usually heat) and oxygen which is usually from the air. |
How does fire exinguishers work? | it works by cooling the fire, or by stopping the oxygen getting tot the fuel. |
Why must water should not be used when oil is burninig? | The water sinks through the oil, and the heatturns the water into steam. The steam rises very quickly to the surface of oil, pushing the burning oil out of the way and making the fire spread out. |
What is the best way to put out a petrol or oil fire? | is to cover it with sands, earth or a fire blanket to keep the oxygen away. |
Why water should never be used on an electrical fire? | You might get an serious electrical shock. |
Explain what is an fuel | A fuel is a substance which contains energy that can be changed into heat energy. |
What is a wax? | substance that contains a lot of carbon joined to hydrogen. |
What is burning also called? | Combustion |
What happens when fuel +oxygen | carbon dioxide + water |
What is a hydrocarbon? | Any chemical that is made of only carbon and hydrogen. |