Chemical Reactions Flashcards

1
Q

Chemical change

  1. How do you know chemical changes are occurring?
  2. What things are chemical changes?
A
1. ~new substances are made
~occur due to chemical reactions
~bonds are broken
~Change of colour
~Fizzing
~Change temperature 
~Change in smell
2. ~Baking a cake
~Burning paper
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2
Q

Physical Changes

  1. How do we know physical changes are occurring?
  2. What things are physical changes?
A
1. ~No new substance made
~Bonds are not broken
~Easy to reverse
2. ~Boiling water
~Melting chocolate
~Smashing a glass
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3
Q

Test for Hydrogen

A

Hydrogen is a gas given off in reactions between a reactive metal and an acid we can test it with the squeaky pop test.

Squeaky pop test:
Place a lit spill into hydrogen
Result:
The hydrogen is visible - it looks like smoke

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4
Q

Test for carbon dioxide

A

Carbon dioxide is a gas given off in reactions between a reactive metal carbonate and an acid. We can test for it with limewater. Colourless limewater becomes cloudy.

Limewater test:
Blow CO2 through a straw of limewater
Result:
The limewater begins to bubble then it turns cloudy

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5
Q

Testing for oxygen

A

Oxygen is a gas given off in the breakdown of hydrogen peroxide. We can test for it with a glowing spill. Oxygen causes the spill to relight.

Glowing splint:
Place a glowing splint into oxygen
Result:
The splint is re-lit

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6
Q

Testing for water

A

When cobalt chloride paper comes into contact with water, it goes from blue to pink.

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7
Q

Conservation of mass

  1. True or false. The mass of reactants=mass of products
  2. Why is this?
A
  1. True

2. This is because no atoms are created or disappear in reaction, they are just moved about.

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8
Q
Thermal decomposition
1. What is thermal decomposition?
2. Complete the word equation:
Copper carbonate—>
Calcium carbonate—>
A
  1. The breaking down of substances using heat.
    2.copper oxide + carbon dioxide
    calcium oxide + carbon dioxide
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9
Q

Word equations

  1. Sodium + chlorine —>
  2. Tin + carbon + oxygen —>
  3. Magnesium + chlorine —>magnesium chloride
A
  1. Sodium chloride
  2. Tin carbonate
  3. Mg + Cl —> MgCl
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10
Q

Why are masses increased after you burn something in oxygen?

A

Because you need oxygen for something to burn, oxygen atoms are added.

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11
Q

Why does mass appear to decrease during thermal decomposition reactions?

A

Because gases are released into the atmosphere and they disperse.

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12
Q

What is neutralisation?

A

 The chemical reaction between an acid and an alkali is called a neutralisation reaction. The pH value of the reaction mixture becomes closer to the seven.

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13
Q

The products that form when a fuel burns

A

~carbon dioxide

~water

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14
Q

Oxidation

A

A Metal being reacted with Oxygen

Magnesium + Oxygen -> Magnesium Oxide
Mg + O2 -> MgO

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15
Q

Precipitation reactions

A

Soluble salt1 + Soluble salt 2 —> NEW Insoluble salt 3 + New soluble salt 4

Swap the product’s first parts

For Example:

Sodium Sulfate + Barium Nitrate —> Barium Sulfate + Sodium Nitrate

Metal 2 Non Metal 1 + Metal 1 Non metal 2

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16
Q

Reaction of different acids with different metal carbonates

A
  • When acids react with carbonates, a salt, water and carbon dioxide are made.
  • The carbon dioxide causes bubbling during the reaction, which is observed as fizzing.
  • It can be detected by passing the gas through limewater, which will go cloudy.
17
Q

Complete combustion

A

•enough oxygen present

Fuel + oxygen -> water + carbon dioxide

18
Q

Incomplete combustion

A

•not enough oxygen

Fuel + oxygen ⇒ carbon + water + carbon monoxide

19
Q

Soluble salts

A
ALL sodium salts - Na
ALL potassium salts - K
ALL ammonium salts -NH
ALL nitrates - NO
MOST sulfates - SO
20
Q

Insoluble salts

A
MOST carbonates - CO
MOST hydroxides - OH
MOST oxides - O
MOST lead compounds - Pb
MOST silver compounds - Ag
Barium Sulfate - BaSO
21
Q

Balancing equations Key information:

A
  • You cannot change small numbers

* You can put numbers in front of elements and compounds