Question

What happens when (Write the balanced equation involved) – (i) Copper is heated in air? (ii) Aluminum oxide is reacted with hydrochloric acid? (iii) Potassium reacts with water? (iv) Cinnabar is heated in air? (v) Aluminum oxide reacts with sodium hydroxide?

Answer 1

Balancing Equation

• Stoichiometric coefficients are added to the reactants and products to balance chemical equations.
• It's significant because the principles of mass conservation and constant proportions require a chemical equation to be applied.

Copper is heated in air

• Copper is heated in the presence of air to produce black copper oxide.
• The balanced equation is as follows:

$2\mathrm{Cu}\left(\mathrm{s}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to 2\mathrm{CuO}\left(\mathrm{s}\right)$

Aluminum oxide is reacted with hydrochloric acid

• Aluminum oxide is treated with hot dilute hydrochloric acid to produce aluminum chloride and water.
• The balanced equation is as follows:

${\mathrm{Al}}_2{\mathrm{O}}_3\left(\mathrm{s}\right)+6\mathrm{HCl}\left(\mathrm{aq}\right)\to 2{\mathrm{AlCl}}_3\left(\mathrm{aq}\right)+3{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$

Potassium reacts with water

• When potassium combines with water, potassium hydroxide and hydrogen gas are formed.
• The balanced equation is as follows:

$2\mathrm{K}\left(\mathrm{s}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to 2\mathrm{KOH}\left(\mathrm{aq}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right)$

Cinnabar is heated in air

• When cinnabar is burned in air, it is converted to mercuric oxide, which produces sulfur dioxide gas.
• The balanced equation is as follows:

$2\mathrm{HgS}\left(\mathrm{s}\right)+3{\mathrm{O}}_2\left(\mathrm{g}\right)\to 2\mathrm{HgO}\left(\mathrm{s}\right)+2{\mathrm{SO}}_2\left(\mathrm{g}\right)$

Aluminum oxide reacts with sodium hydroxide

• Sodium aluminate and water are formed when aluminum oxide combines with sodium hydroxide.
• The balanced equation is as follows:

${\mathrm{Al}}_2{\mathrm{O}}_3\left(\mathrm{s}\right)+2\mathrm{NaOH}\left(\mathrm{aq}\right)\to 2{\mathrm{NaAlO}}_2\left(\mathrm{aq}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$