Which is a chemical reaction?

[zak100]

Hi,

I know that chemical reaction is one in which original substances change their properties. Can we say that a rotten milk or a floating ice is an example of a chemical reaction? Somebody please guide me.

 

Zulfi,

[Sensei]

4 minutes ago, zak100 said:

I know that chemical reaction is one in which original substances change their properties.

This is not a correct definition. In a solid state, a substance has different properties than in a liquid state, but is not an example of a chemical reaction.

[swansont]

Can you take a stab at what chemical reaction you think might be going on?

[zak100]

Hi,

I found following definition of a chemical reaction:

Quote

a process in which one or more substances, the reactants, are converted to one or more different substances, the products. Substances are either chemical elements or compounds. A chemical reaction rearranges the constituent atoms of the reactants to create different substances as products.

Based upon this it looks like floating of ice is not a chemical reaction because it is not causing any rearrangement of atoms. But in case of rotting of milk we have rearrangment of atoms, so it is chemical reaction. Is it correct?

rotting of milk (chemical reaction): formation of acid i.e taste of milk becomes sour

floating of ice (chemical reaction): none, but there is a physical change i.e. ice is melting.

 

 

 

Zulfi.

[studiot]

1 hour ago, zak100 said:

I found following definition of a chemical reaction:

Quote

a process in which one or more substances, the reactants, are converted to one or more different substances, the products. Substances are either chemical elements or compounds. A chemical reaction rearranges the constituent atoms of the reactants to create different substances as products.

Based upon this it looks like floating of ice is not a chemical reaction because it is not causing any rearrangement of atoms. But in case of rotting of milk we have rearrangment of atoms, so it is chemical reaction. Is it correct?

rotting of milk (chemical reaction): formation of acid i.e taste of milk becomes sour

floating of ice (chemical reaction): none, but there is a physical change i.e. ice is melting.

 

Interesting definition that is nearly correct, but not quite.

Chemical reactions involve the breaking and/or the making of chemical bonds between the atoms. It is not necessary for new substances to be formed, although it often happens.

This will normally involve rearranging the atoms, but there are rearrangements, such as the phenomenon of creep, that do not involve the breaking or making of bonds.

Floating of ice is a physical phenomenon, but melting or solidifying , vapourising or condensing are chemical reactions as they involve breaking/making of bonds.

Does this help ?