Question

Carbon and oxygen react to produce carbon dioxide. What is the weight of oxygen required to convert $1.5g$ of carbon to carbon dioxide?
$(A)2g$
$(B)6g$
$(C)1g$
$(D)4g$

Answer 1

Carbon and oxygen react in different proportions to form carbon monoxide and carbon dioxide. To solve this question, we will first calculate the mass of reactants and products and determine the amount of oxygen which reacts with that of carbon. Then we will be able to calculate the weight of oxygen required to react with $1.5g$ of carbon.

Complete answer:
Carbon and oxygen react in different proportions to form carbon monoxide and carbon dioxide.
We will now write the chemical reaction taking place between carbon and oxygen to form carbon dioxide.
$C + {O_2} \to C{O_2}$
In this reaction, the mass of carbon is $12g$ .
Mass of Oxygen is $32g$ .
Mass of Carbon dioxide is $44g$ .
Therefore, we can see that 12 g of carbon is reacting with $32g$ of oxygen. And hence, using stoichiometric calculations:
$1.5g$ of carbon will react with $= \left( {\dfrac{{32}}{{12}}} \right) \times 1.5$
$1.5g$ of carbon will react with $= 4g$ oxygen
Therefore, four gram of oxygen is required to convert $1.5g$ of carbon to carbon dioxide.
Hence, the correct option is $(D)4g$ .

Note:
The type of questions in which we have to find the weight of the product formed from a given amount of reactants, we first calculate the moles of each reactant that react with each other to form the product. Then we find out the limiting reagent among the reactants. Therefore, according to the given weight of the limiting reagent, we find out the weight of the product formed.