melting of wax is a physical thing?

Answer 1

There's a clue in determining chemical or physical.

Like Omega-3 fish oil, it must be kept in cold condition to prevent the double bonds break down.

Like heating milk, overheating it will cause the proteins to crumble and deform. It is a chemical reaction.

If melting a wax is a chemical reaction, then after cooled, it will deform. But in real, it is a physical reaction.

I surely know you have this knowledge, it is just that this question can make you recall this fact.

Answer 2

For the most part, you can think of physical changes as this - can you get back what you started with - is it still the same thing on a molecular level?

If I take a piece of wood and make a table leg out of it - it is still the same wood, just in a different shape. If I really really wanted to (which I wouldn't) - I could take all the pieces that I hacked off the original piece of wood and glue them back together - let's just say I didn't sand it yet ;)

Think of this:

you take an ice cube out of the freezer. What makes up an ice cube? H2O. You put it on the counter, what happens to it? It's going to melt. What makes up that liquid substance that is on your counter? Well, it's still H2O! So then you take a bunch of ice cubes, let them melt, and then boil them. That steamy stuff coming out of the pan, what is that? Why that's steam - and what is steam? Right H2O

Phase changes do not break bonds, they just cause the same molecule to become a solid, liquid, or gas. Melting your wax is just like melting an ice cube - it's still plain old wax. If it's still wax, that represents a physical change.

A chemical change is one where you have a chemical reaction. What you start with is NOT what you end up with on a molecular level. If I take water, and I run electrical current through it I can make H2 gas and O2 gas. Well H2 gas and O2 gas are not the same thing chemically as my H2O molecules. Therefore, I have CHANGED the species and I not longer have H2O molecules so that is a chemical change.

How about we go back to our table leg. I hated it, it was ugly so I threw it in the fireplace. I burned it up. Chemical change. I turned the wood into ash, CO2, water vapor, and a bunch of other stuff, none of which is wood!

While chemical changes can bo backwards and forwards, a lot of times, at this level of learning physical/chemical there will be a lot of black and white questions where you can't go back. If you can go back to the original thing: physical
If you can't - chemical

Think about these: I drop a glass and it shatters: physical: if my mom made me I could glue the pieces back together - the tiny pieces are still glass, they are just in a different shape!

milk spoiling: chemical: it's never gonna be fresh again, it has changed chemically

tearing a piece of paper: each half is still the same paper! physical

rust forming: iron and oxygen are combining to make a new compound, called rust: can you go back - sure - but you have to SCRAPE the rust away from the surface of your iron - you didn't change the rust back into iron, you scrape it off and throw it away - rusting is chemical

Answer 3

Yeah. Compare the densities of solid and liquid paraffin. That's some feat of efficient molecular packing in the solid, eh?

Answer 4

Yep, a change of state from solid to liquid is a physical process.

Answer 5

Yes.

Answer 6

yes