Question

What is the balanced equation for combustion of glucose?

Answer 1

Hint: Combustion Reaction: It is a chemical reaction in which a substance is burned in the presence of air i.e., oxygen to produce energy. In case of the hydrocarbons, they undergo combustion reactions in presence of oxygen to produce carbon dioxide and water.

Complete answer:
The molecular formula of glucose is $$C_6{H}_{12}{O}_6$$.
Combustion reaction for glucose is as follows:
$$C_6{H}_{12}{O}_6+O_2\to C{O}_2+H_{2}O$$
To balance the given chemical reaction, we need to follow certain steps:
Step-1: Identify the reactants and products in the reaction.
For the given chemical reaction, reactants are $$C_6{H}_{12}{O}_6$$ and $$O_2$$ while products are $$C{O}_2$$ and $$H_{2}O$$.
Step-2: Counting the number of atoms of each substituent in reactant as well as product.
For reactants-
Number of Carbon atoms $$\Rightarrow 6$$
Number of Hydrogen atoms $$\Rightarrow 12$$
Number of Oxygen atoms $$\Rightarrow 8$$
For products-
Number of Carbon atoms $$\Rightarrow 1$$
Number of Hydrogen atoms $$\Rightarrow 2$$
Number of Oxygen atoms $$\Rightarrow 3$$
Step-3: Balancing carbon atoms in the chemical reaction.
In reactants, there are six carbon atoms whereas in product there is only one carbon atom. Hence $$6$$ is added as the coefficient of carbon dioxide in the product.
 $$C_6{H}_{12}{O}_6+O_2\to 6C{O}_2+H_{2}O$$
Step-4: Counting the number of atoms of each substituent for new reaction.
For reactants-
Number of Carbon atoms $$\Rightarrow 6$$
Number of Hydrogen atoms $$\Rightarrow 12$$
Number of Oxygen atoms $$\Rightarrow 8$$
For products-
Number of Carbon atoms $$\Rightarrow 6$$
Number of Hydrogen atoms $$\Rightarrow 2$$
Number of Oxygen atoms $$\Rightarrow 13$$
Step-5: Balancing hydrogen atoms in the chemical reaction.
In reactants, there are twelve hydrogen atoms whereas in product there are only two hydrogen atoms. Hence $$6$$ is added as the coefficient of water in the product.
 $$C_6{H}_{12}{O}_6+O_2\to 6C{O}_2+6H_{2}O$$
Step-6: Counting the number of atoms of each substituent for new reaction.
For reactants-
Number of Carbon atoms $$\Rightarrow 6$$
Number of Hydrogen atoms $$\Rightarrow 12$$
Number of Oxygen atoms $$\Rightarrow 8$$
For products-
Number of Carbon atoms $$\Rightarrow 6$$
Number of Hydrogen atoms $$\Rightarrow 12$$
Number of Oxygen atoms $$\Rightarrow 18$$
Step-7: Balancing oxygen atoms in the chemical reaction.
In product, there are eighteen oxygen atoms whereas in reactants there are only eight oxygen atoms. Hence $$6$$ is added as the coefficient of oxygen gas in the reactant.
 $$C_6{H}_{12}{O}_6+6O_2\to 6C{O}_2+6H_{2}O$$
Step-8: Counting the number of atoms of each substituent for new reaction.
For reactants-
Number of Carbon atoms $$\Rightarrow 6$$
Number of Hydrogen atoms $$\Rightarrow 12$$
Number of Oxygen atoms $$\Rightarrow 18$$
For products-
Number of Carbon atoms $$\Rightarrow 6$$
Number of Hydrogen atoms $$\Rightarrow 12$$
Number of Oxygen atoms $$\Rightarrow 18$$
As the number of atoms of each substituent in the reactants is equal to the number of atoms in the product. So, the equation is balanced.
Hence balanced reaction for the combustion of glucose is:
$$C_6{H}_{12}{O}_6+6O_2\to 6C{O}_2+6H_{2}O$$

Note:
Combustion reaction is always performed for one mole of substance i.e., only one mole of hydrocarbon will react with oxygen gas to undergo combustion. Also, it is mandatory to check the number of atoms of each substituent in reaction to reduce confusion.