Chemical And Physical Reactions
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What do chemical reactions always do?
They always make new substances.
Are they easily reversible?
No, they are not easily reversible.
Do they involve energy transfers?
Yes
Are physical reactions reversible?
Yes
What are physical reactions?
Physical changes of state.
Name an example of a chemical change.
Burning diesel to make carbon dioxide and water.
Name an example of a physical change.
Dissolving sugar in tea to make it taste sweet.
Another chemical change…
Baking raw cake to make a cooked cake.
Another physical change…
Boiling water to make steam!
Can you name some improvements to make an experiment a fair test?
Use the same starting mass. Use the same starting temp. Same length of burning time. Raise temperature same amount.
What are hydro carbons?
Fossil fuels. Candle
Are hydro carbons non renewable?
Yes.
Will hydro carbons eventually run out, and if so, when?
They will eventually run out because they take millions of years to form.
Name examples of non renewables.
Coal, oil, natural gas.
What is an alternative fuel?
Hydrogen
What reacts with oxygen to form water?
Hydrogen.
Hydrogen+oxygen > water. A) Is harmful carbon dioxide released? B) Is hydrogen obtained from methane?
A) No B) Yes
Is hydrogen flammable?
Yes, it can explode.
What does does thermal decomposition mean?
Breaking a substance down, using heat, into 2 or more products.
Reaction of copper carbonate in limewater?
Turns black and gives out the carbon dioxide to turn the limewater cloudy the fastest.
Reaction of zinc carbonate in limewater?
Turns yellow/green hot and gives out the carbon dioxide to turn the limewater cloudy, not so fast.
Reaction of calcium carbonate in limewater.
Produced bubbles of gas in the limewater, but it dosen’t turn really cloudy in 5 mins.
Conclusion of calcium,zinc and copper carbonate in limewater?
So calcium is more reactive than zinc+copper. Zinc is less reactive than calcium but more reactive than copper.
What is the most reactive of the carbonates?
Calcium + zinc carbonate