Question
Question: In the reaction \( {H_2} + {O_2} \to {H_2}O \) . If \( 6g \) of \( {H_2} \) combines with \( 64g \) ...
In the reaction H2+O2→H2O . If 6g of H2 combines with 64g of O2 . Find the mass of excess reagent left?
(A) 32g
(B) 48g
(C) 16g
(D) None of these
Solution
Balanced chemical reaction: The reaction in which the number of atoms on both the sides i.e. on the reactant side and on the product side are same, are known as balanced chemical reaction. By balanced chemical reaction we get the relation between the number of moles of reactants with the number of moles of products.
Complete step by step solution
First of all we will talk about reagents and products.
Reagents: those compounds which react with each other to form the other compounds, are known as reagents. They are present on the left side of the reaction.
Products: The compounds formed by the reaction of reagents, are known as products. They are present on the right side of the reaction.
Balanced reaction: The reaction in which the number of all atoms on both sides i.e. on the reactant side and on the product side are same, are known as balanced reactions. By the balanced chemical reaction we get to know the relation between the number of moles of reactants with the number of moles of product.
In the given question the reaction is as:
H2+O2→H2O this is not a balanced reaction. After balancing the reaction we will get
H2+21O2→H2O i.e. if two grams of hydrogen will react with 16g of oxygen then 18g of water molecule will be form.
But if we use 6g of hydrogen then 48g of oxygen will require to produce 54g of water.
But here we are given 6g of H2 combined with 64g of O2 so 64−48=16g oxygen which is excess reagent (present in large quantity) will remain unreacted.
Hence option C is right.
Note
Number of moles is defined as the ratio of mass of substance to the molar mass of the substance. In the balanced chemical reaction we can get the information about how much moles will react with how much moles of other reactants to form the product of given quantity.