Question

Acrylonitrile, ${{C}_{3}}{{H}_{3}}N$, is the production of a king of synthetic fibre (acrylics). It can be made from propylene, ${{C}_{3}}{{H}_{6}}$, by reaction with nitric oxide, NO
${{C}_{3}}{{H}_{6}}(g)+NO(g)\to {{C}_{3}}{{H}_{3}}N(g)+{{H}_{2}}O(g)+{{N}_{2}}(g)(Unbalanced)$
How many grams acrylonitrile may be obtained from 420 g of propylene and excess NO?
(A)- 265 kg
(B)- 530 kg
(C)- 1060 kg
(D)- 795 kg

Answer 1

Hint: Start this solution by calculating the number of moles of acrylonitrile formed from the 420 kg or propylene. Then balance the equation and see how many many of propylene reacts and how many moles of acrylonitrile is produced. Then calculate how many moles will be produced from the calculated moles of propylene.

Complete answer:
-Let us start by finding the number of moles of acrylonitrile which will be formed from 420 kg of propylene and excess of NO-
Converting 420 kg into grams $=420\times 1000$
Moles of propylene $=\dfrac{420\times 1000}{42}=10,000\text{ moles}$
-Now, balancing the unbalanced equation for the formation of acrylonitrile-
${{C}_{3}}{{H}_{6}}(g)+NO(g)\to {{C}_{3}}{{H}_{3}}N(g)+{{H}_{2}}O(g)+{{N}_{2}}(g)(Unbalanced)$
$4{{C}_{3}}{{H}_{6}}(g)+6NO(g)\to {{C}_{3}}{{H}_{3}}N(g)+6{{H}_{2}}O(g)+{{N}_{2}}(g)(Balanced)$
-It is clear from the balanced equation that,
4 moles of ${{C}_{3}}{{H}_{6}}$reacts to give $\to $ 4 moles of ${{C}_{3}}{{H}_{3}}N$
Therefore, 10,000 moles of ${{C}_{3}}{{H}_{3}}$will give $\to \dfrac{4\times 10,000}{4}=10,000\text{ moles of }{{\text{C}}_{3}}{{H}_{3}}N$
-Calculating the mass of ${{C}_{3}}{{H}_{3}}N$which will be formed $=10,000\times 53=530,000gm=530kg$

Hence, the correct answer is option B.

Additional information:
Let us now see the uses and harmful effects of acrylonitrile.
-Acrylonitrile is majorly used as a monomer in the preparation of homopolymer such as polyacrylonitrile, or several important copolymers, such as styrene-acrylonitrile (SAN), acrylonitrile butadiene styrene (ABS) and other synthetic rubber such acrylonitrile butadiene (NBR).
-Some amount of acrylonitrile is also used as a fumigant, which is a method of pest control in which an area is filled with gaseous pesticides due to which pests die with suffocation.
-In organic synthesis, acrylonitrile and its derivatives such as 2-chloro acrylonitrile functions as dienophiles in Diels-Alder reactions.
-Acrylonitrile is also used as a precursor in the industrial synthesis of acrylamide and acrylic acid.
-Despite various uses of acrylonitrile, it does have many health effects.
-Acrylonitrile is highly flammable and toxic to living beings especially human beings at low doses. It undergoes explosive polymerization and its burning releases fumes of hydrogen cyanide and oxides of nitrogen.
-International Agency for Research on Cancer (IARC) has classified acrylonitrile as carcinogenic.

Note:
Balancing a chemical reaction is very important for studying a chemical reaction. An unbalanced chemical reaction tells us which reactants react and forms what product, whereas a balanced reaction tells us how many moles of each reactant reacts and how many moles of product are formed. Balanced reactions tell us how many electrons are exchanged and how much is the energy consumed or released. As a conclusion, a balanced reaction is important in doing calculations.