Jump to content

Thermal Decomposition of Carbonates


Daave

Recommended Posts

As we look at the metals on the periodic table, the further we go along, the more difficult that metal's carbonate is to decompose. i.e. Sodium Carbonate is more readily decomposed than Calcium Carbonate. I need to devise a method of experimentally testing this.

 

My thoughs as such are; we heat the carbonate (as a solid - possibly in water [but NOT aqueous]), and using limewater - test at what temperature carbon dioxide is released.

 

My question is - is this approach feasible, what equipment will I need, is there a better way of proving the hypothesis. I have access to varoius carbonates, limewater, and ordinary lab equipment (glassware, bunsens, filtration devices, etc)

 

 

Any suggestions? :)

Link to comment
Share on other sites

Sodium Carbonate is more readily decomposed than Calcium Carbonate.

 

Not true! Calcium carbonate decomposes at much lower temperatures. If you want to explore decomposition temperatures of carbonates you need very strong heating. I suppose that some alkali metal carbonates do not decompose even in bunsen burner flame.

Link to comment
Share on other sites

Not true! Calcium carbonate decomposes at much lower temperatures.

AH yes - I got it the wrong way round - the actual hypothesis I had to test experimentally is:

 

"that the ease of decomposition of carbonates is in the reverse order of the Periodic Table"

 

that being from easiest to most difficult, not the way around - as I had initially interpreted it.

 

When heating it (at such high temperatures), what would be the best way to collect the carbon dioxide let off? Or again - as I asked in my original post - is there some easier way to do it?

Link to comment
Share on other sites

If you can use analytical scales you may measure weight of remaining oxide instead of collecting CO2.

 

Some of carbonates can be decomposed in test tube. You have to put bent tube (usally glass is used, but when collecting CO2 metallic tubes are as good) through stopper and collect gas to flask or graduated cylinder that is capsized on water tank.

Link to comment
Share on other sites

Sodium carbonate will decompose upon heating. You have to be under the proper environment, however. (Performing the heating under a vacuum is the best way to accomplish this so that you can remove the CO2 as it is forming).

Link to comment
Share on other sites

I do not need to prove that a carbonate will separate into it's oxide and carbon dioxide - but that the carbonates further down the periodic table are easier to decompose than those higher in the periodic table i.e. Calcium carbonate decomposing more easily than Sodium carbonate.

Link to comment
Share on other sites

take some carbonate in a flaks/tuest tube. put a thermoter in ther and also have stopper draiwing the CO2 into lime water. then note the temperature at witch a precipetate forms. And heat its slowly for most accurate results.

Link to comment
Share on other sites

my teacher used to tell me sodium carbonate doesn't decompose on heat

 

I was under the impression that every compound would decompose if enough heat was added...BTW your teacher sounds lost is he a PE teacher? :rolleyes:

 

~Scott

Link to comment
Share on other sites

agreed - definitely a lost P.E. teacher - BenSon is right, any substance will decompose given enough heat, the temperature at which this will occur is dependant on various things including the strength of the intra-molecular bonds and the distance of the valence electrons from the nucleus.

Link to comment
Share on other sites

I see... maybe it's so called out of syllabus at my level (even the public exam states the answer as cannot be decomposed) maybe I'll learn it at A level

Even the Haber process and Le Chaterlier's Principle are not required in my exams, I bet I'll learn more at A level

thanks anyway

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.