Chemical Reactions Rearranging Atoms

​Year 9 Chemistry

Chemical reactions involve rearranging atoms to form new substances; during chemical reaction mass is not created or destroyed. (ACSSU178)

​What we will be learning...

• Chemical reactions can be explained through chemical equations

         

• Understanding and identifying products and reactants in reactions

       

• Conduct a chemical reaction and explain the process using chemical equations.

         

• Understand and explain how energy is involved in chemical reactions

Reorder

Reorder from smallest to largest

• Neutron

• Atom

• Element

• Molecule

• Compound

1

2

3

4

5

• 1
• 2
• 3
• 4
• 5

Poll

If you were to look at this equation which would you think were the products and reactants?

$$C_3H_8+5O_2\rightarrow4H_2O\ +3CO_2$$  

• Left side = products

  Right side= reactants

• Left side = reactants

  Right side = produts

• Both reactants

• Both products

1. Write out the chemical equation

2. Make a list of the number of atoms for each element in reactants and products

3. ​Times the numbers of the same elements until you find a matching number

4. That number is called the coefficient and is written at the front of the molecule

​

​How to balance equations

​

​Activity

We will now use the cut-out squares on your desk to balance the equations.

Use a blank piece of paper to list the elements and how many are on both sides of the equations.

Then place the relevant coefficient in front of the molecule. so the equation is balanced.

Subject | Subject

Multiple Choice

What answer did you get for the first question?

• $$1H_{2\ }+1O_2\rightarrow\ 1H_2O$$  

• $$2H_{2\ }+1O_2\rightarrow\ 2H_2O$$  

• $$5H_{2\ }+4O_2\rightarrow\ 6H_2O$$  

Multiple Choice

Second question?

• $$1C_{2\ }+1O_2\rightarrow\ 1CO_2$$  

• $$1C_{2\ }+4O_2\rightarrow\ 2CO_2$$  

• $$1C_{2\ }+2O_2\rightarrow\ 2CO_2$$  

• $$7C_{2\ }+12O_2\rightarrow\ 14CO_2$$  

Multiple Choice

And the third?

• $$1H_2\ +1Cl_2\rightarrow\ 1HCl$$  

• $$1H_2\ +1Cl_2\rightarrow\ 2HCl$$  

• $$4H_2\ +4Cl_2\rightarrow\ 2HCl$$  

• $$2H_2\ +2Cl_2\rightarrow\ 1HCl$$  

Draw

Balance the equation...

Draw

Lets try a harder one...