Question

An amount of $5$ moles of A, $6$ moles of B and excess amount of C are mixed to produce a final product D, according to the reactions:
$A + 2B \to I$
$I + C \to B + D$
What is the maximum moles of D, which can be produced assuming that the products formed can also be reused in the reactions?
A. $3$ moles
B. $4.5$ moles
C. $5$ moles
D. $6$ moles

Answer 1

Hint: We know that in physical chemistry, mole concept is a term that is used to express the amount of a substance. Molar mass of a substance is defined as the total mass of one mole of a substance. It is usually denoted by g/mol.

Complete step by step answer:
We know that in chemical reactions, the molar mass of different reactants are different.
Let us take an example,
${H_2} + {O_2} \to {H_2}O$
But this is not the correct way of writing a chemical equation. To check for the number of moles required we need to first balance the chemical equation by writing appropriate coefficients for both reactants and products.
The same equation we can write as –
$2{H_2} + {O_2} \to 2{H_2}O$
Thus, here we can observe that two moles of hydrogen when reacted with one mole of oxygen produces two moles of water.
Likewise, in the question we $5$ moles of A substance reacting with $6$ moles of B substance. The A and B together gives a product I. And the equation given in the question is,
$A + 2B \to I$
By observing the equation, we can say that one mole of A requires two moles of B to produce one mole of C.
Thus $3$ moles of A require $6$ moles of B to produce $3$ moles of I.
In the second reaction, one mole of I and one mole C combines to form one mole of B and one mole of D- $I + C \to B + D$
But, already we have produced $3$ moles of I. Thus three moles of I will react with three moles of C to produce three moles of B and three moles of D.
Now, we have $3$ moles of newly formed B, which will be used in further reaction.
Now, out $5$ moles of A we have $2$ moles left.
Thus, in the second time we will use $1.5$ moles of A to react with $3$ moles of B, to produce $1.5$ moles of I.
$1.5A + 3B \to 1.5I$
Further, with $1.5$ moles of I we will use $1.5$ moles of C to produce $1.5$ moles of B and $1.5$ moles of D.
$1.5I + 1.5C \to 1.5B + 1.5D$
Here, we have obtained newly formed $1.5$ moles of B.
Lastly, we have only $0.5$ moles of A left.
We will use $0.5$ moles of A with $1$ mole of B to produce $0.5$ mole of I.
$0.5A + 1B \to 0.5I$
Likewise, $0.5I + 0.5C \to 0.5B + 0.5D$.
Now, we carefully sum up all the number of moles of D substance, then we have = $3 + 1.5 + 0.5 = 5$moles.

So, the correct answer is Option C.

Note: Molar mass is a very useful concept. We need to remember that it is thus widely used in almost every reaction. In industries where the production takes place on a large scale it is important to use the molar mass concept to compute the requirement of chemicals. Molar mass concept is efficient and avoids wastage of chemicals. It tells us the accurate number of moles of reactants and products required for the reaction. And it also determines the moles of products which will be obtained from the applied reaction.