PPT: Chemical Reaction and Equations

 Page 1


Understanding 
Chemical Reactions
• Chemical reaction is a process in which one or more reactants are 
converted to one or more products. 
• During a chemical reaction, chemical change occurs.
• The substances that undergo chemical change are called 
reactants. The new substance formed is called product.
Page 2


Understanding 
Chemical Reactions
• Chemical reaction is a process in which one or more reactants are 
converted to one or more products. 
• During a chemical reaction, chemical change occurs.
• The substances that undergo chemical change are called 
reactants. The new substance formed is called product.
Examples of Chemical Reactions
Burning Magnesium 
Ribbon
•Burning of a clean 
magnesium ribbon with a 
dazzling white flame to form 
white powder (magnesium 
oxide). 
• It is due to the reaction of 
magnesium with oxygen in 
air. Burner
Lead Nitrate Reaction
• T ake lead nitrate solution in 
a test tube. 
• Add potassium iodide 
solution. 
• A yellow precipitate of lead 
iodide appears at the 
bottom(lead iodide.)
Zinc and Hydrochloric 
Acid
• Take few zinc granules in a 
conical flask or test tube. 
• Add dilute HCI or H250 g.
• Bubbles are observed 
around zinc granules due to 
release of hydrogen. 
• Conical flask becomes hot. 
H, gas
Page 3


Understanding 
Chemical Reactions
• Chemical reaction is a process in which one or more reactants are 
converted to one or more products. 
• During a chemical reaction, chemical change occurs.
• The substances that undergo chemical change are called 
reactants. The new substance formed is called product.
Examples of Chemical Reactions
Burning Magnesium 
Ribbon
•Burning of a clean 
magnesium ribbon with a 
dazzling white flame to form 
white powder (magnesium 
oxide). 
• It is due to the reaction of 
magnesium with oxygen in 
air. Burner
Lead Nitrate Reaction
• T ake lead nitrate solution in 
a test tube. 
• Add potassium iodide 
solution. 
• A yellow precipitate of lead 
iodide appears at the 
bottom(lead iodide.)
Zinc and Hydrochloric 
Acid
• Take few zinc granules in a 
conical flask or test tube. 
• Add dilute HCI or H250 g.
• Bubbles are observed 
around zinc granules due to 
release of hydrogen. 
• Conical flask becomes hot. 
H, gas
Identifying Chemical Reactions
The following observations helps to determine whether a chemical reaction has taken place: 
Change in state, Change in colour, Evolution of a gas, Change in temperature.
Change in state:
A change in state, such as from a solid to 
a liquid, can indicate a chemical reaction.
Change in colour:
Alterations in color can be a visible sign 
that a chemical reaction has occurred.
Evolution of gases:
The evolution of a gas, like the formation 
of bubbles, is a clear indicator of a 
chemical change.
Change in temprature:
Significant changes in temperature, either 
an increase or decrease, often accompany 
chemical reactions.
Page 4


Understanding 
Chemical Reactions
• Chemical reaction is a process in which one or more reactants are 
converted to one or more products. 
• During a chemical reaction, chemical change occurs.
• The substances that undergo chemical change are called 
reactants. The new substance formed is called product.
Examples of Chemical Reactions
Burning Magnesium 
Ribbon
•Burning of a clean 
magnesium ribbon with a 
dazzling white flame to form 
white powder (magnesium 
oxide). 
• It is due to the reaction of 
magnesium with oxygen in 
air. Burner
Lead Nitrate Reaction
• T ake lead nitrate solution in 
a test tube. 
• Add potassium iodide 
solution. 
• A yellow precipitate of lead 
iodide appears at the 
bottom(lead iodide.)
Zinc and Hydrochloric 
Acid
• Take few zinc granules in a 
conical flask or test tube. 
• Add dilute HCI or H250 g.
• Bubbles are observed 
around zinc granules due to 
release of hydrogen. 
• Conical flask becomes hot. 
H, gas
Identifying Chemical Reactions
The following observations helps to determine whether a chemical reaction has taken place: 
Change in state, Change in colour, Evolution of a gas, Change in temperature.
Change in state:
A change in state, such as from a solid to 
a liquid, can indicate a chemical reaction.
Change in colour:
Alterations in color can be a visible sign 
that a chemical reaction has occurred.
Evolution of gases:
The evolution of a gas, like the formation 
of bubbles, is a clear indicator of a 
chemical change.
Change in temprature:
Significant changes in temperature, either 
an increase or decrease, often accompany 
chemical reactions.
Writing Chemical Equations:
The description of a chemical reaction can be written in a shorter form. The simplest way is word-
equation. E.g. 
Magnesium + Oxygen —>Magnesium oxide 
• The reactants are written on left-hand side (LHS) with a plus sign (+) between them. 
• Products are written on the right-hand side (RHS) with a plus sign (+ between them. 
• The arrowhead points towards the products and shows the direction of the reaction.
Page 5


Understanding 
Chemical Reactions
• Chemical reaction is a process in which one or more reactants are 
converted to one or more products. 
• During a chemical reaction, chemical change occurs.
• The substances that undergo chemical change are called 
reactants. The new substance formed is called product.
Examples of Chemical Reactions
Burning Magnesium 
Ribbon
•Burning of a clean 
magnesium ribbon with a 
dazzling white flame to form 
white powder (magnesium 
oxide). 
• It is due to the reaction of 
magnesium with oxygen in 
air. Burner
Lead Nitrate Reaction
• T ake lead nitrate solution in 
a test tube. 
• Add potassium iodide 
solution. 
• A yellow precipitate of lead 
iodide appears at the 
bottom(lead iodide.)
Zinc and Hydrochloric 
Acid
• Take few zinc granules in a 
conical flask or test tube. 
• Add dilute HCI or H250 g.
• Bubbles are observed 
around zinc granules due to 
release of hydrogen. 
• Conical flask becomes hot. 
H, gas
Identifying Chemical Reactions
The following observations helps to determine whether a chemical reaction has taken place: 
Change in state, Change in colour, Evolution of a gas, Change in temperature.
Change in state:
A change in state, such as from a solid to 
a liquid, can indicate a chemical reaction.
Change in colour:
Alterations in color can be a visible sign 
that a chemical reaction has occurred.
Evolution of gases:
The evolution of a gas, like the formation 
of bubbles, is a clear indicator of a 
chemical change.
Change in temprature:
Significant changes in temperature, either 
an increase or decrease, often accompany 
chemical reactions.
Writing Chemical Equations:
The description of a chemical reaction can be written in a shorter form. The simplest way is word-
equation. E.g. 
Magnesium + Oxygen —>Magnesium oxide 
• The reactants are written on left-hand side (LHS) with a plus sign (+) between them. 
• Products are written on the right-hand side (RHS) with a plus sign (+ between them. 
• The arrowhead points towards the products and shows the direction of the reaction.
Writing Chemical E quations:
• Chemical equations can be simplified by using chemical formulae. 
• A chemical equation represents a chemical reaction. 
• If the number of atoms of each element is not same on LHS & RHS, the equation is unbalanced. 
It is called a skeletal chemical equation. If same, it is balanced.