Chemical Reactions- Half Term Flashcards
(20 cards)
Name one observation that suggests a chemical reaction might be happening.
A new gas is produced/bubbles, a precipitate forms/solid appears, a colour change, a change in temperature/heat given off or taken in, light is produced.
Name another observation that suggests a chemical reaction might be happening.
A new gas is produced/bubbles, a precipitate forms/solid appears, a colour change, a change in temperature/heat given off or taken in, light is produced.
Give an example of a physical change.
Ice melting, water boiling, dissolving sugar in water, crumpling paper.
When ice freezes into water, is this a physical or chemical change?
A physical change.
What happens to the particles during a physical change?
The particles rearrange themselves, but their chemical identity remains the same (e.g., water molecules are still water molecules whether they are ice, liquid, or steam).
What happens to the particles during a chemical change?
The particles themselves break apart and rearrange to form new substances with different chemical identities.
Give an example of a chemical reaction.
Frying an egg, burning wood, rusting iron, baking a cake.
When you fry an egg, is this a physical or chemical change?
A chemical change.
What are the three things needed for a fire to burn, according to the ‘fire triangle’?
Heat, Fuel, Oxygen.
What is ‘fuel’ in the context of the fire triangle?
Something that can burn (e.g., wood, paper, gas).
What is ‘oxygen’ in the context of the fire triangle?
The gas in the air that helps things burn.
What is ‘heat’ in the context of the fire triangle?
The energy needed to start and sustain a fire.
What is the general word equation for combustion?
Fuel + Oxygen → Carbon Dioxide + Water (and often heat and light energy).
What is needed for a fire to burn?
Heat, Fuel, and Oxygen (the three parts of the fire triangle).
How can you put out a fire by removing the ‘heat’ from the fire triangle? Give an example.
By cooling it down, for example, by pouring water on it.
Why does pouring water on a fire help to put it out?
The water absorbs the heat, cooling the fuel below its ignition temperature, and can also create steam which blocks oxygen.
How can you put out a fire by removing the ‘fuel’ from the fire triangle? Give an example.
By removing what is burning, for example, by separating burning material from unburnt material.
Why does removing the fuel help to put out a fire?
If there’s no fuel, there’s nothing left to burn.
How can you put out a fire by removing the ‘oxygen’ from the fire triangle? Give an example.
By suffocating it, for example, by covering it with a fire blanket or sand.
Why does removing the oxygen help to put out a fire?
Without oxygen, the fuel cannot react with it to burn.
