Question

q.3. if the reactants on the left side of a chemical equation are c₂h₅oh + 3o₂; the products in a balanced equation could be .........................
a) 2co₂ + 4h₂o
b) 2co₂ + 3h₂o
c) 3co₂ + 2h₂o
d) 4co₂ + 3h₂o

Explanation:

Step1: Count carbon atoms

The reactant $\mathrm{C}_{2}\mathrm{H}_{5}\mathrm{OH}$ has 2 carbon atoms. In a balanced chemical - equation, the number of carbon atoms in the products must equal the number of carbon atoms in the reactants.

Step2: Analyze each option for carbon - atom balance

• Option a: In $2\mathrm{CO}_{2}+4\mathrm{H}_{2}\mathrm{O}$, the number of carbon atoms is 2.
• Option b: In $2\mathrm{CO}_{2}+3\mathrm{H}_{2}\mathrm{O}$, the number of carbon atoms is 2.
• Option c: In $3\mathrm{CO}_{2}+2\mathrm{H}_{2}\mathrm{O}$, the number of carbon atoms is 3.
• Option d: In $4\mathrm{CO}_{2}+3\mathrm{H}_{2}\mathrm{O}$, the number of carbon atoms is 4.

Step3: Count hydrogen atoms

The reactant $\mathrm{C}_{2}\mathrm{H}_{5}\mathrm{OH}$ has 6 hydrogen atoms.

• Option a: In $2\mathrm{CO}_{2}+4\mathrm{H}_{2}\mathrm{O}$, the number of hydrogen atoms is $4\times2 = 8$.
• Option b: In $2\mathrm{CO}_{2}+3\mathrm{H}_{2}\mathrm{O}$, the number of hydrogen atoms is $3\times2=6$.
• Option c: In $3\mathrm{CO}_{2}+2\mathrm{H}_{2}\mathrm{O}$, the number of hydrogen atoms is $2\times2 = 4$.
• Option d: In $4\mathrm{CO}_{2}+3\mathrm{H}_{2}\mathrm{O}$, the number of hydrogen atoms is $3\times2 = 6$.

Step4: Count oxygen atoms

The reactants $\mathrm{C}_{2}\mathrm{H}_{5}\mathrm{OH}+3\mathrm{O}_{2}$ have $1 + 3\times2=7$ oxygen atoms.

• Option a: In $2\mathrm{CO}_{2}+4\mathrm{H}_{2}\mathrm{O}$, the number of oxygen atoms is $2\times2 + 4\times1=8$.
• Option b: In $2\mathrm{CO}_{2}+3\mathrm{H}_{2}\mathrm{O}$, the number of oxygen atoms is $2\times2+3\times1 = 7$.
• Option c: In $3\mathrm{CO}_{2}+2\mathrm{H}_{2}\mathrm{O}$, the number of oxygen atoms is $3\times2+2\times1 = 8$.
• Option d: In $4\mathrm{CO}_{2}+3\mathrm{H}_{2}\mathrm{O}$, the number of oxygen atoms is $4\times2+3\times1 = 11$.

Answer:

B. $2\mathrm{CO}_{2}+3\mathrm{H}_{2}\mathrm{O}$