C3: Chemical Reactions Flashcards

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1
Q

All chemical reacitons do what 2 things?

A
  1. Make new substances
  2. Transfer energy to or from the surroundings.
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2
Q

What is a chemical reaction?

A

Where atoms are rearranged to make new substance.

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3
Q

Most chemical reacitons are not easily reversible. What does this mean?

A

At the end of a reaction it is very hard to get back what you started with.

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4
Q

When an ice cube melts is this a chemical reaciton or a physical change? Why?

A

Physical change

because it can be reversed e.g. changes of state can be reversed.

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5
Q

What is a catalyst?

A

A substance that can be added to a chemical reaction to speed it up.

They are not used up in the reaction.

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6
Q

What sort of things might you oberserve when a chemical reaction is happening?

A

Fizzing/Bangs

Smells

Temperature changes

Colour changes

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7
Q

When are chemical reactions not so useful?

A

Rusting is a chemical reaction.

This damages cars, boats and bridges.

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8
Q

The particles that make up all matter are called…

A

atoms

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9
Q

Is a physical change a chemical reaction?

A

No because it is reversible e.g. melting chocolate.

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10
Q

Chemical reactions are useful for making substances such as:

A

Medicines - paracetamol

Fabrics - polyester

Building materials - cement

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