Question

Which chemical equation is unbalanced?

Answer 1

The correct option is 2.

For a chemical equation to be balanced, the number of atoms of each element present in the reactants must be the same with that present in the products. If the number of atom of any element at any of the two side of the reaction is not the same, then the equation is not balanced. Looking at the options given above, it will be noticed that for option 2, the number of Sr atom at the reactant side is 1 while at the product side it is 2. This shows that the equation is not balanced.

Answer 2

The unbalanced chemical equation is $\boxed{2.{\text{ Sr}} + {{\text{O}}_2} \to {\text{SrO}}}$.

Further explanation:

Chemical reaction:

The chemical conversion of one set of substances into another is termed as chemical reaction. The substances that were originally present before the occurrence of chemical reaction are known as reactants whereas the substances that are formed once the reaction goes to completion are called products. Any chemical reaction involves the bond breaking between the reactants and new bond formations occur in products.

The chemical reaction in which equal number of atoms of the different elements is present in the reactant as well as in the product side is known as balanced chemical reaction. Law of mass and energy conservation are followed by each and every balanced equation.

1. ${\text{C}} + {{\text{O}}_2} \to {\text{C}}{{\text{O}}_{\text{2}}}$  

On the reactant side,

Number of carbon atoms is 1 while that of oxygen atoms is 2.

On the product side,

Number of carbon atoms is 1 while that of oxygen atom is 2.

The number of atoms of each type is the same on both sides of the reaction and therefore this reaction is balanced.

2. ${\text{Sr}} + {{\text{O}}_2} \to {\text{2SrO}}$  

On the reactant side,

Number of strontium atoms is 1 while that of oxygen atoms is 2.

On the product side,

Number of strontium atoms is 2 while that of oxygen atom is 2.

The number of strontium atoms on both sides of the reaction is not same and therefore this reaction is unbalanced.

3. ${\text{6}}{{\text{H}}_2} + 3{{\text{O}}_2} \to {\text{6}}{{\text{H}}_2}{\text{O}}$  

On the reactant side,

Number of hydrogen atoms is 12 while that of oxygen atoms is 6.

On the product side,

Number of carbon atoms is 12 while that of oxygen atom is 6.

The number of atoms of each type is the same on both sides of the reaction and therefore this reaction is balanced.

4.  ${{\text{H}}_2} + {{\text{H}}_2} + {{\text{O}}_2} \to {{\text{H}}_2}{\text{O}} + {{\text{H}}_2}{\text{O}}$

On the reactant side,

Number of hydrogen atoms is 4 while that of oxygen atoms is 2.

On the product side,

Number of hydrogen atoms is 4 while that of oxygen atom is 2.

The number of atoms of each type is the same on both sides of the reaction and therefore this reaction is balanced.

Learn more:

1. Balanced chemical equation: brainly.com/question/1405182
2. Identification of all of the phases of the reaction: brainly.com/question/8926688

Answer details:

Grade: High School

Subject: Chemistry

Chapter: Chemical reactions and equations

Keywords: balanced, unbalanced, Sr, O2, H2, H2O, C, reaction, conversion, reactants, products, SrO, CO2.