Question

When gases are released from a reaction what type of change has occurred?

Answer 1

Answer:

Color Changes. A change in color often indicates a chemical change.

Temperature Changes. Changes in temperature might also indicate a chemical change has occurred.

Precipitates. The formation of a precipitate is a sign that a chemical change has occurred.

Light Emission.

Gas Production.

Explanation:

Answer 2

Answer:

A chemical change has occurred.

Explanation:

A chemical change is accompanied by a change in the chemical composition of the substance.

A color change, formation of a precipitate, evolution of a gas , temperature change are the indications of a chemical change.

For example  

$2AlCl_3 (aq)+3Na_2 CO_3 (aq)>Al_2 (CO_3 )_3 (s)+6NaCl(aq)$

Here we see the formation of a precipitate or an insoluble solid $Al_2(CO_3 )_3 (s)$

A chemical reaction is accompanied by a change in temperature.

Reaction in which heat is evolved is an exothermic reaction and reaction in which heat is absorbed is called as endothermic reaction.

Combustion reaction is an example in which heat and light is given off and it is exothermic.

Some reactions we see gas gets evolved. For example electrolysis of water produces Hydrogen and oxygen gas.

$2H_2O>2H_2+O_2$