Is a gas always produced by a chemical reaction?

Answer 1

gas is not always produced. Sometimees the reaction can change color. Also the temperature can change. gas is not always produced. Sometimees the reaction can change color. Also the temperature can change.

Answer 2

No.

Chemical reactions can yield any state of matter, depending on the reagents (stuff that goes into the reaction).

Gas can be the result of a physical reaction as well. For example, adding sufficient heat energy can turn a liquid or even some solids directly into a gas, or removing heat energy from a plasma will also yield a gas (that is usually no longer ionized like the plasma).

Answer 3

It depends on the kind of bubbles!

When a liquid boils, it forms bubbles - but in this case it's only a physical change in the state of aggregation (from liquid to gaseous).

Another possibility in a physical cause of bubbles could be "out-gassing" of a physically solved gas in a liquid e.g. when you heat water of a lake, there forms tiny bubbles of oxygen because solubility decreases with rising temperature.

And now the case of a chemical reaction:

There you have a gas forming because of a chemical reaction - for example when you take the reaction between a (reactive) metal and an acid:

Mg + 2 HCl --> MgCl2 + H2(g)

In this case there is hydrogen (as a gas) which forms bubbles.

In a bottle of gassed mineral water you have both; physical and also chemical evolution of bubbles. Most of the carbon dioxide is solved physically in the water, but some is also bound chemically as carbonic acid H2CO3 which is not that stable and on shaking/heating splits up into CO2 and water:

H2O + CO2 <---> H2CO3

So forming of bubbles is not always an indication of a chemical reaction, but besides boiling of liquids a lot of gas evolutions are caused by a reaction!

Answer 4

No. There are examples of reactions when the product is just a solid or just an aqueous solution.

Answer 5

Yes. the signs of a chemical reaction include: releasing gas (commonly bubbles) and emitting light or heat

Answer 6

no bc liquid changed to gas is a physical property

Answer 7

No, eg when water evaporates no bubbles are formed.

Answer 8

Yes it does