Question

Q.65. Give the balanced equation for each of the following chemical reactions

a. Glucose (C₆H₁₂O₆)reacts with oxygen gas to produce gaseous carbon dioxide and water vapour.

b. Solid iron (III) sulfide reacts with gaseous hydrogen chloride to form solid iron (III) chloride and hydrogen sulfide gas.

c. Carbon disulfide liquid reacts with ammonia gas to produce hydrogen sulphide gas and solid ammonium thiocyanate (NH₄HCN) .

Short answer

Answer

The balanced equation for each of the following chemical reactions are:

$$\begin{gathered} \mathrm{a})({\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6)\left(\mathrm{s}\right)+6{\mathrm{O}}_2\left(\mathrm{g}\right)\to 6{\mathrm{CO}}_2\left(\mathrm{g}\right)+6{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right) \\ \mathrm{b}){\mathrm{Fe}}_2{\mathrm{S}}_3+6\mathrm{HCl}\left(\mathrm{g}\right)\to 2{\mathrm{FeCl}}_3\left(\mathrm{g}\right)+3{\mathrm{H}}_2\mathrm{S}\left(\mathrm{g}\right) \\ \mathrm{c}){\mathrm{CS}}_2\left(\mathrm{l}\right)+2{\mathrm{NH}}_3\left(\mathrm{g}\right)\to {\mathrm{H}}_2\mathrm{S}\left(\mathrm{g}\right)+{\mathrm{NH}}_4\mathrm{SCN}\left(\mathrm{s}\right) \end{gathered}$$

Step-by-step solution

Step-by-Step Solution Step 1: Definition

Atoms are preserved in chemical reactions; therefore, balancing is crucial. The number of atoms in each type of reactant and product must be equal. In addition, an unbalanced chemical equation has limited utility. It's important to remember that the formulae of the compounds remain the same while balancing a chemical equation.

The unbalanced chemical equation

a)

The reactants are glucose $\left({\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6\right)$ and oxygen (O₂) , and the products are carbon dioxide (CO₂) and water vapor (H₂O) in the given chemical reaction.

$\left({\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6\right)\left(\mathrm{s}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to {\mathrm{CO}}_2\left(\mathrm{g}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right)$

is an imbalanced chemical equation.

The chemical equation to be balanced

For a chemical equation to be balanced, the number of atoms of each kind must be the same in both the reactant and the product.

There are 12 hydrogens on the left side and 2 on the right side of the balancing hydrogen. There will be 12 hydrogen atoms on both sides when coefficient 6 is applied to (H₂O).

Similarly, if (CO₂) is given the coefficient 6, there will be 6 carbon atoms on both sides.

$\left({\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6\right)\left(\mathrm{s}\right)+6{\mathrm{O}}_2\left(\mathrm{g}\right)\to 6{\mathrm{CO}}_2\left(\mathrm{g}\right)+6{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right)$

The reaction of Glucose (C6H12O6) reacts with oxygen gas

When it comes to balancing oxygen, there are 8 atoms on the left (6 from (C₆H₁₂O₆) and 2 from (O₂) ) and 18 on the right (12 from (CO₂) , and 6from (H₂O) ). There will be 18 oxygen atoms on both sides if coefficient 6 is set to (O₂) on both sides.

As a result, the balanced chemical equation required will be:

$\left({\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6\right)\left(\mathrm{s}\right)+6{\mathrm{O}}_2\left(\mathrm{g}\right)\to 6{\mathrm{CO}}_2\left(\mathrm{g}\right)+6{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right)$

The unbalanced chemical equation

b)

Solid iron (III) sulfide, Fe₂S₃ (s) and gaseous hydrogen chloride, HCl (g) are reactants and solid iron (III) chloride FeCl₃(s) and hydrogen sulfide gas H₂S(g) are products.

Because Fe³⁺ ions are present in iron (III) sulfide and the sulfide ion is S^2- , the formula for iron (III) sulfide is Fe₂S₃. Because the ion of chloride is Cl^-, the formula for iron (III) chloride is FeCl₃.

${\mathrm{Fe}}_2{\mathrm{S}}_3\left(\mathrm{s}\right)+\mathrm{HCl}\left(\mathrm{g}\right)\to {\mathrm{FeCl}}_3\left(\mathrm{s}\right)+{\mathrm{H}}_2\mathrm{S}\left(\mathrm{g}\right)$ is theimbalanced chemical equation.

The chemical equation to be balanced

Starting with iron, there are two atoms on the left side and one on the right side.

If FeCl₃ (s) has a coefficient of 2, there will be two iron atoms on both sides.

${\mathrm{Fe}}_2{\mathrm{S}}_3\left(\mathrm{s}\right)+\mathrm{HCl}\left(\mathrm{g}\right)\to 2{\mathrm{FeCl}}_3\left(\mathrm{s}\right)+{\mathrm{H}}_2\mathrm{S}\left(\mathrm{g}\right)$

Step 7: Solid iron  (III) sulfide reacts with gaseous hydrogen chloride

There are 6 chlorine atoms on the right side and 1 atom on the left side of the balance. There will be 6 atoms of chlorine on both sides when coefficient 6 is applied to HCl. In the same way, balancing hydrogen by assigning coefficient 3 to H₂S will result in 6 hydrogen atoms on both sides.

As a result, the balanced chemical equation required will be:

${\mathrm{Fe}}_2{\mathrm{S}}_3\left(\mathrm{s}\right)+\mathrm{HCl}\left(\mathrm{g}\right)\to 2{\mathrm{FeCl}}_3\left(\mathrm{s}\right)+3{\mathrm{H}}_2\mathrm{S}\left(\mathrm{g}\right)$

The imbalanced chemical equation

c)

The reactants are liquid carbon disulfide CS₂ (I) and ammonia gas NH₃ (g) , whereas the products are hydrogen sulfide gas H₂S(g) and solid ammonium thiocyanate (NH₄SCN) (s).

${\mathrm{CS}}_2\left(\mathrm{l}\right)+{\mathrm{NH}}_3\left(\mathrm{g}\right)\to {\mathrm{H}}_2\mathrm{S}\left(\mathrm{g}\right)+{\mathrm{NH}}_4\mathrm{SCN}\left(\mathrm{s}\right)$ is an imbalanced chemical equation.

Step 9: Carbon disulfide liquid reacts with ammonia gas

The number of carbon and sulfur atoms is already balanced in the above equation. To be balanced, only nitrogen and hydrogen atoms are required.

On both sides of the equation, if coefficient 2 is applied to NH₃, there will be 2 nitrogen atoms and 6 hydrogen atoms.

As a result, the balanced chemical equation required is:

${\mathrm{CS}}_2\left(\mathrm{l}\right)+2{\mathrm{NH}}_3\left(\mathrm{g}\right)\to {\mathrm{H}}_2\mathrm{S}\left(\mathrm{g}\right)+{\mathrm{NH}}_4\mathrm{SCN}\left(\mathrm{s}\right)$