Consider the following combinations and tell if

they are physical or chemical change:

Hydrogen + Oxygen Water

Red Clay + white Clay Pink Clay

Justify your answer for each combination.

If thermic refers to heat what do you think the

terms exothermic and endothermic mean?

Endothermic Reactions are chemical reactions

that require energy while exothermic reaction

are those that release Energy.

Burning or Combustion is when something

reacts with Oxygen, just as the burning of

magnesium that produced huge amount of

light. In order to happen, we need to expose

something to fire in order to burn.

Is Burning Endothermic or Exothermic

Reaction?

“An apple a day keeps the doctor away”..But

what if the apples appear to be brown?

What can you do about this?

In this game we have Vitamin C tablets and

water. Each group of students will think for 5

minutes to plan for the fastest way to react

Vitamin C with water. The groups will

compete together. The fastest group will be

the winner.

● Concentration: The more the concentration

the more is the speed or rate.

● Temperature: The more the temperature

the more is the speed.

● Surface area: The more area of reactants

exposed the greater is the speed.

Enzymes are said to be biocatalyst. “Bio”

means it is produced by cells “ catalyst”

means helper. They help chemical reactions

take place, just as those in our body.

Let’s watch this video:

https://www.youtube.com/watch?v=XTUm-

75-PL4

Chemical reaction is the chemical change that

is modeled by the chemical equation. It is said

to be an equation since the number of atoms

in the reactants are equal to the number of

atoms in the products due to the Law of

Conservation Of Mass

The Law of the Conservation of Mass states

that "Mass is conserved in a closed system".

For chemical equations - that means that the

number of each type of atom in the reactants

is equal to the number of the same type of

atoms in the product.

atoms in reactants = atoms in products

A simple example goes a long way. We can form water by

combining hydrogen gas (H2) and oxygen (O2) . The

reaction looks like this:

H2 + O2 H2O

If you do some of the calculations you will find this:

2 atoms of hydrogen + 2 atoms of oxygen = 3 atom

molecule of water (there is one oxygen lost)

H2 + O2 H2O

Reactants Products

2 H 2H

2O not balanced 1O

H2+ O2 H2O

In order to balance the chemical reaction, we

have to change the coefficient (the number in

the text box) we can multiply the H2O

coefficient by 2 to balance the Oxygen.

1 11

H2 + O2 2 H2O

Reactants Products

2 H not balanced 2H 4H

2O 1O 2O

To Balance the Hydrogen atoms we need to

multiply the coefficient of Hydrogen in the

reactant by 2

2 H2 + O2 2 H2O

Reactants Products

2 H 4H 2H 4H

2O 1O 2O

HOORAY!! It is now BALANCED...

Al + O2 Al2O3

C2H6 + O2 CO2 + H2O

Fe2O3 + H2SO4 Fe2(SO4)3 + H2O

CO2 + H2 CH4 + H2O

Al + CuO Al2O3 + Cu

K2O + H2O KOH

I2 + Na2S2O3 NaI + Na2S4O6

(NH4)2CO3 NH3 + CO2 + H2O