Question

Classify the following as physical or chemical properties: Zinc dissolves in Hydrochloric acid with the evolution of Hydrogen gas.

Answer 1

Physical property:

• A physical property is known as any property that is measurable, and which describes a state of a physical system.
• Physical properties are properties that can be observed without bringing a chemical change.
• It is mainly used to identify or describe a substance.

Chemical property:

• A chemical property is known as any property that gets observed or measured when a substance undergoes a chemical change.
• A chemical reaction needs to be conducted to produce new substances showing the chemical properties.
• It is mainly used to predict how the reaction occurs in a substance.

Zinc dissolves in Hydrochloric acid with the evolution of Hydrogen gas:

• The given property is describing the chemical property of the substance Zinc.
• Here, a chemical reaction occurs between Zinc and Hydrochloric acid to give out Zinc chloride and Hydrogen gas, for which the reaction can be given as :

$\underset{\left(\mathrm{Zinc}\right)}{\mathrm{Zn}\left(\mathrm{s}\right)}+\underset{\left(\mathrm{Hydrochloric}\mathrm{acid}\right)}{2\mathrm{HCl}\left(\mathrm{aq}\right)}\to \underset{\left(\mathrm{Zinc}\mathrm{chloride}\right)}{{\mathrm{ZnCl}}_2\left(\mathrm{aq}\right)}+\underset{\left(\mathrm{Hydrogen}\mathrm{gas}\right)}{{\mathrm{H}}_2\left(\mathrm{g}\right)}$

• The products formed here are also new substances, which depict the chemical change to take place in the given process.

Hence, the example given as Zinc dissolves in hydrochloric acid with the evolution of Hydrogen gas represents to be a chemical property.