Question

In a hydrogen molecule, the two hydrogen atoms are held together by a single bond with a bond energy of 436 kj/mol of hydrogen. in other words, to break the h–h bonds in one mole of molecular hydrogen requires the expenditure of 436 kj of energy. using the balanced chemical equation for the formation of water from oxygen and hydrogen (shown above), and interpreting the stoichiometric coefficients as mole amounts, how much energy must be expended in breaking the h–h bonds?

Answer 1

The energy utilized in breaking H-H bond is $\boxed{872\;{\text{kJ}}}$.

Further Explanation:

The chemical reaction that contains equal number of atoms of the different elements in the reactant as well as in the product side is known as balanced chemical reaction. The chemical equation is required to be balanced to follow the Law of the conservation of mass.

Bond energy is the amount of energy required to break one mole of a covalent bonded molecule into its atoms.

The steps to balance a chemical reaction are as follows:

Step 1: Complete the reaction and write the unbalanced symbol equation.

In the reaction, hydrogen gas $\left({{{\text{H}}_2}}\right)$ reacts with oxygen gas $\left({{{\text{O}}_2}}\right)$ to form water molecule $\left({{{\text{H}}_{\text{2}}}{\text{O}}}\right)$. The physical state of ${{\text{H}}_2}$ and ${{\text{O}}_2}$ is gas and ${{\text{H}}_{\text{2}}}{\text{O}}$ is liquid. The unbalanced chemical equation is as follows:

${{\text{H}}_2}\left(g\right)+{{\text{O}}_2}\left(g\right) \to{{\text{H}}_2}{\text{O}}\left( l \right)$

Step 2: Then we write the number of atoms of all the different elements that are present in a chemical reaction in the reactant side and product side separately.

 • On reactant side,

Number of hydrogen atoms is 2.

Number of oxygen atoms is 2.

• On product side,

Number of oxygen atom is 1.

Number of hydrogen atoms is 2.

Step 3: Initially, we try to balance the number of other atoms of elements except for carbon, oxygen, and hydrogen by multiplying with some number on any side but the given reaction consists of only hydrogen and oxygen atoms.

${{\text{H}}_2}\left(g\right)+{{\text{O}}_2}\left(g\right)\to{{\text{H}}_2}{\text{O}}\left( l \right)$

Step 4: After this, we balance the number of atoms of carbon and then hydrogen atom followed by oxygen atoms.

To balance the number of atoms of oxygen and hydrogen atoms we have to multiply ${{\text{H}}_2}$ by 2 and ${{\text{H}}_{\text{2}}}{\text{O}}$ by 2. Now the reaction is,

$\boxed{\text{2}}{{\text{H}}_2}\left(g\right)+{{\text{O}}_2}\left(g\right) \to \boxed2{{\text{H}}_2}{\text{O}}\left(l\right)$

Step 5: Finally, we check the number of atoms of each element on both the sides. If the number is same then the chemical equation is balanced. The balanced chemical equation is as follows:

${\text{2}}{{\text{H}}_2}\left(g\right)+{{\text{O}}_2}\left(g\right)\to 2{{\text{H}}_2}{\text{O}}\left(l\right)$

In the balanced chemical reaction, the two moles of ${{\mathbf{H}}_{\mathbf{2}}}$ reacts with one mole of ${{\mathbf{O}}_{\mathbf{2}}}$  to form two moles of ${{\mathbf{H}}_{\mathbf{2}}}{\mathbf{O}}$ .

The bond energy of H-H bond is  $436\;{\text{kJ/mol}}$.

The amount of energy is breaking two moles of is as follows:

$\begin{aligned}{\text{Amount of energy}}&={\text{2 mol}}\left({{\text{bond energy of H}}-{\text{H}}}\right)\\&={\text{2 mol}}\left({436\;{\text{kJ/mol}}}\right)\\&=872\;{\text{kJ}}\\\end{aligned}$

Therefore the energy used in breaking H-H bond is ${\mathbf{872}}\;{\mathbf{kJ}}$.

Learn more:

1. Balanced chemical equation: brainly.com/question/1405182

2. Determine the net ionic equation: brainly.com/question/9061741

Answer details:

Grade: High School

Subject: Chemistry

Chapter: Chemical reaction and equation

Keywords: Balancing, H2, O2, H2O, phases, physical state, solid, liquid, gas, aqueous, coefficients, and bond energy,436 kJ/mol, and 872 kJ.

Answer 2

Answer: 873 kJ of energy will be required to break two moles of hydrogen gas.

$2H_2+O_2\rightarrow 2H_2O$

Above chemical equation shows that two moles of hydrogen gas is reacting with one mole of oxygen gas to give two mole of water molecule.

Bond energy of H-H = 436kJ

According to reaction we have two moles hydrogen,so energy required to break the

H-H bond in two moles of hydrogen gas will be:

$2\times \text{bond energy of H-H bond}$

$2\times {436}$ = 872kJ

872kJ of energy will be required to break H-H bond in two moles of hydrogen gas.