Question

how do we tell a chemical reaction had taken place

Answer 1

Great Question! :D

Answer:

When a chemical reaction takes place new products are formed. It's like I put Sodium(a silvery metal) in a test tube and in return I get a green substance ( let's say Sodium hydroxide). It's not magic, It's chemical reaction!

So, that way we know when a reaction takes place. I once saw some vid in which some dude scared other people of his place like ya know appearing and then disappearing, they thought it's some ghost. He did nothing but used a robo and used concentrated sulphuric acid so that the metal of the robo decays and everyone thinks the person disappeared. So, that's chemistry, what he did was a chemical reaction between a metal and an acid.

Whenever a reaction occurs, new products are formed. That is new substance with different chemical arrangements. Now, chemistry occurs in microscopic world, like cmon we can't see the transfer of electrons from atom to atom.

So, we've got some signs that might conclude a chemical reaction has taken place.

• Color Change.
• Production of odor.
• Change of Temperature.
• Evolution of a gas (formation of bubbles)
• Precipitate (formation of a solid)

COLOR CHANGE

like we have a special kinda paper dipped in lichens, litmus paper, used as an indicator to distinguish acids from bases. It comes in two colors - red and blue which change their colors alternatively when placed in a base a nd an acid respectively. That's a chemical reaction I know of.

ODOR CHANGE

in case of odors, ya know how fresh food and rotten food smell differently, that's another chemical reaction.

TEMPERATURE CHANGE

For temperature change, we've got two kinds of reactions - endothermic and exothermic.

endothemric absorbs heat whereas exothermic releases heat like. like when you place electral powder on your tongue your tongue feels cold. that's an endothermic reaction that causes the tongue to absorb surrounding heat.

and exotehrmic is simply lighting of some candles or fire or anything that feels warm. But yeah don't think heaters produce heat due to these reactions it's an electrical appliance and the cause of its heat is current and resistances.

GAS EVOLUTION

you'll see bubbles forming in a liquid that's also cause of chemical reactions. Like, you must have seen in cartoons how contaminated waters are green and bubbly (lol). That I guess is due to the fact that the waters have chemicals in high amounts.

PRECIPITATE

Precipitate is a residue of a reaction. it's mainly produced off double displacement reactions. And the Precipitate is obtained in a liquid solution that means the reactions are liquid solutions whereas one product is in solid state.

_______________

Well! That's a lot. Hope I helped :}