Question

Which answer below correctly identifies the type of change and the explanation when magnesium comes into contact with hydrochloric acid?
physical change because no color change occurred

physical change because the observation of a gas forming is evidence of a state change, which is
reversible

chemical change because a temperature change occurred, a solid disappeared, and a gas was
produced

chemical change because two substances were mixed, which always results in the formation of a
new substance

Answer 1

Answer:

A chemical change because a temperature change occurred, the solid disappeared and a gas was produces

Explanation:

Magnesium reacts with hydrochloric acid releasing energy, and leading to the formation of  magnesium chloride and hydrogen gas. This is represented by the equation below:

Mg₍s₎ + 2HCl₍aq)⇒ MgCl₂₍aq₎ + H₂₍g₎

Answer 2

Answer:

chemical change because a temperature change occurred, a solid disappeared, and a gas was  produced

Explanation:

In a chemical change there is a change in the chemical property of the reactant such that a new product is formed such as rusting of iron to form iron oxide. In a physical change there is phase change of the substance such as melting of ice.  

Mg is a metal that combines with the acid HCl to form the salt magnesium chloride, MgCl₂ and hydrogen gas, H₂. The chemical property of salts and gases are completely different from that of metal and acids.  

Mg + HCl = MgCl₂ + H₂