Chemical Reactions Flashcards
Chemical change
- How do you know chemical changes are occurring?
- What things are chemical changes?
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
Physical Changes
- How do we know physical changes are occurring?
- What things are physical changes?
1. ~No new substance made ~Bonds are not broken ~Easy to reverse 2. ~Boiling water ~Melting chocolate ~Smashing a glass
Test for Hydrogen
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
Test for carbon dioxide
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
Testing for oxygen
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
Testing for water
When cobalt chloride paper comes into contact with water, it goes from blue to pink.
Conservation of mass
- True or false. The mass of reactants=mass of products
- Why is this?
- True
2. This is because no atoms are created or disappear in reaction, they are just moved about.
Thermal decomposition 1. What is thermal decomposition? 2. Complete the word equation: Copper carbonate—> Calcium carbonate—>
- The breaking down of substances using heat.
2.copper oxide + carbon dioxide
calcium oxide + carbon dioxide
Word equations
- Sodium + chlorine —>
- Tin + carbon + oxygen —>
- Magnesium + chlorine —>magnesium chloride
- Sodium chloride
- Tin carbonate
- Mg + Cl —> MgCl
Why are masses increased after you burn something in oxygen?
Because you need oxygen for something to burn, oxygen atoms are added.
Why does mass appear to decrease during thermal decomposition reactions?
Because gases are released into the atmosphere and they disperse.
What is neutralisation?
 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.
The products that form when a fuel burns
~carbon dioxide
~water
Oxidation
A Metal being reacted with Oxygen
Magnesium + Oxygen -> Magnesium Oxide
Mg + O2 -> MgO
Precipitation reactions
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