Chemical Reactions page 86-98 Flashcards
What are chemical reactions?
A chemical reaction is a change in which atoms rearranged to create new substances. The atoms are joined together in one way before the reaction and in a different way after the reaction.
What do all chemical reactions do?
They make new substances.
They transfer energy to or from the surroundings.
What things might you notice to determine if it is a chemical reaction?
You might see huge flames or tiny sparks.
You might notice a sweet smell or a foul stink.
You might feel the chemicals getting hotter or colder. You might hear a loud bang or gentle fizzing.
( you don’t need to memorise all of this at least know two )
What useful substances do chemical reactions form?
They form medicines such as paracetamol.
They form fabrics such as polyester.
They from building materials such as cement.
What type chemical reaction is not useful?
Rusting is not useful it can damage cars, boats and bridges.
What do chemists use catalysts for?
They use them to speed up a slow reaction.
What is a physical change?
A change that is reversible, in which new substances are not made.
What are some examples of physical changes?
Examples of physical changes include changes of state, and dissolving.
What two elements react to make carbon dioxide?
Carbon and oxygen react to make carbon dioxide.
What does carbon dioxide from as?
It forms as an invisible gas.
What happens if you heat iron fillings and sulphur powder?
The mixture glows red, a new substance forms.
What are reactants?
Reactants are the starting substances in chemical reaction.
What are products?
The substances made in the reactions are called products.
What are hazards?
Hazards are possible sources of danger.
What are risks?
Risks are the chances of damage or injury from hazards.
What does the arrow in a word equation?
The arrow in a word equation means reacts to make.
What is a fuel?
A fuel is material that burns to transfer energy by heating.
What are some examples of a fuel?
Fuel include petrol, diesel, coal, hydrogen and waste cooking oil.
What is burning also called?
Burning is also called combustion.
What is methane a compound of?
Methane is a compound of carbon and hydrogen.
What is a fossil fuel?
A fuel made from the remains of animals and plants that died millions of years ago.
What do fossil fuels include?
They include coal, oil and natural gas.
What does non-renewable mean?
Non-renewable means that they cannot be replaced once they have been used, they will run out one day.
What are oxidation reactions?
Burning reactions are oxidation reactions.
When oxygen reacts with other substances what type of reaction is this known as?
An oxidation reaction.
What happens in decomposition reactions?
In decomposition reactions, a compound breaks down onto simpler elements or compounds.
What is a thermal decomposition reaction?
When a substance breaks down on heating, the reaction is a thermal decomposition reaction.
What is a discrete variable?
A discrete variable is described by words, or by numbers that can only have certain values, such as shoe sizes.
What is conservation of mass?
In any chemical reaction, the total mass of reactants is equal to the total mass of products. This is called conservation of mass. Mass is also conserved in physical changes.
What do balanced symbol equations show?
The formulae of reactants and products
How the atoms are rearranged
The relative amounts of reactants and products.
What is an endothermic change?
Melting and boiling reactions are endothermic changes.
What is an exothermic change?
All burning reactions are exothermic.
