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chemical reactions
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can anyone tell me which of the following are chemical reactons and why or why not.
thanx in advance. the sooner the better please!
a firework going off
starting a car engine
bursting a balloon
grilling bacon
grass growing
thanx in advance. the sooner the better please!
a firework going off
starting a car engine
bursting a balloon
grilling bacon
grass growing
Answers
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A chemical reaction occurs when there is a change at the molecular level. That is to say the chemicals change.
If you're stuck a good idea is to think whether or not you can run it backwards - it's not 100% reliable but a good indicatior at this level.
So in the first chemicals burn to set off a firework, in the second the petrol burns when the car starts - both burning both chemical reactions.
In the third one compressed air in the balloon escapes, you could catch the air, recompress it in another balloon - this is a physical process.
Grilling bacon causes chemical changes to the meat - you can't ungrill it and similarly with grass growing, energy and nutrients combine chemically and give the grass energy to grow.
If you're stuck a good idea is to think whether or not you can run it backwards - it's not 100% reliable but a good indicatior at this level.
So in the first chemicals burn to set off a firework, in the second the petrol burns when the car starts - both burning both chemical reactions.
In the third one compressed air in the balloon escapes, you could catch the air, recompress it in another balloon - this is a physical process.
Grilling bacon causes chemical changes to the meat - you can't ungrill it and similarly with grass growing, energy and nutrients combine chemically and give the grass energy to grow.
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