C1 Chemical Equations (page 99)

Question 1

Chemical changes are shown using what?

Answer 1

Chemical Equations

Question 2

What is this equation is asking you to explain?
(reactants and products)

Methane + Oxygen&raquo_space;»> Carbon Dioxide + Water

Answer 2

The molecules on the left-hand side of the equation are called the reactanct (because they react with each other)

The molecules on the right-hand are called products (because they’ve been produced from the reactant.

Question 3

Explain what this equation means?

Magnesium + Oxygen &raquo_space;»»»» Magnesium Oxide
2Mg + O2 &raquo_space;»»»> 2MgO

Answer 3

Chemical changes can be shown in a kind of shorthand, using symbol equations.

Symbol equations just show the symbols of formulas of the reactants and the products.

Symbol equations need to be balanced. - Always has the same number o atoms on both sides - they just cant disappear.

Question 4

How do you balance equations?

Answer 4

By putting the numbers in front of the formulas where needed. Take this equation for reacting sulfuric acid with sodium hydroxide:

eg; H2SO4 + NaOH&raquo_space;»»> Na2SO4 + H20 (all numbers are small)

The formulas are all correct but the numbers of some atoms don’t match up on both sides.

You can’t change formulas like H2SO4 to H2SO5 - you can only put numbers in front of them.

Question 5

Balance the equation:

Fe + Cl2&raquo_space;»» FeCl3

Answer 5

2Fe + 3Cl2 &raquo_space;»> 2FeCl3

Question 6

Tell me how you balance Symbol Equations?

Answer 6

1. Find an element that doesn’t balance and pencil in a number, to try and sort it out.
2. See where it gets you. It may create another imbalance, but if so, pencil in another number and see where that gets you.
3. Carry on chasing unbalanced elements and it’ll sort itself out pretty quickly.

Question 7

How would you balance this equation?

H²SO⁴ + NaOH &raquo_space;»»» Na2SO4 + H2O

Answer 7

1) You will notice from the equation we’re short of H atoms on the right hand side.

The only thing you can do about that is make it 2H2O instead of just H2O

2) But that now gives you too many H atoms and O atoms on the right hand side, so to balance that up you could try putting 2NaOH on the Left hand side

H2SO4 + 2NaOH &raquo_space;»»> Na2SO4 + 2H2O

3) And suddenly there it is! Everything balances, and you’ll notice the Na just sorted itself out.

Question 8

Hydrogen and oxygen molecules are formed in a reaction where water splits apart, for this reaction:

a) State the word equation
b) Give a balanced symbol equation

Answer 8

a) Water &raquo_space;»> hydrogen + oxygen

b) 2H2O &raquo_space;»» 2H2 + O2

Question 9

What is the charge of a proton?

Answer 9

Protons have a positive electrical charge on one (+1) and a mass of 1 atomic mass unit

Question 10

give the formula for

a: Carbon Dioxide
b: Sodium Carbonate

Answer 10

a) CO2

b) Na²Cl³