Question

Which combustion equation violates the law of conservation of matter? A) CH4 + 2O2 -> CO2 + 2H2O B) C3H8 + 6O2 -> 3CO2 + 4H2O C) 2C6H14 + 19O2 -> 12CO2 + 14H2O D) 2C8H18 + 25O2 -> 16CO2 + 18H2O

Answer 1

Answer : The combustion equation violates the law of conservation of matter is, (B) $C_3H_8+6O_2\rightarrow 3CO_2+4H_2O$

Explanation :

According to the law of conservation of matter, the number of atoms of each elements of reactant side must be equal to the product side in the chemical reaction. Or we can say that the mass of reactant side must be equal to the mass of product side in the chemical reaction.

(A) $CH_4+2O_2\rightarrow CO_2+2H_2O$

This combustion equation follow the law of conservation of matter.

(B) $C_3H_8+6O_2\rightarrow 3CO_2+4H_2O$

This combustion equation does not follow the law of conservation of matter because in this reaction, the atoms of carbon and hydrogen elements are equal on both the sides but the atoms of oxygen element on reactant side are not equal to the product side.

(C) $2C_6H_{14}+19O_2\rightarrow 12CO_2+14H_2O$

This combustion equation follow the law of conservation of matter.

(D) $2C_8H_{18}+25O_2\rightarrow 16CO_2+18H_2O$

This combustion equation follow the law of conservation of matter.

Hence, the combustion equation violates the law of conservation of matter is, equation (B)

Answer 2

B - C3H8 + 6O2 -> 3CO2 + 4H2O

THis is because Oxygen is not balanced on both sides, thus defying the law of conservation of matter.

On the reactants side of the equation, there are 12 Oxygen atoms, however, on the products side, there are only 10 Oxygen atoms.

Hope this helps!