HS Chemistry - Writing heat in an equation/decomposition

[Toadie]

My teacher is pretty strict about details, and I'm working on an assignment about writing/balancing chemical reactions. The question is:

 

When heated, calcium carbonate decomposes to form calcium oxide and carbon dioxide. Write the equation for this reaction.

 

He never really mentioned how to write the heat part in the equation, so I kind of just winged it. This is what I got:

 

Ca2(CO3)2 + heat → 2CaO + 2CO2

 

Have I written that correctly? (Sorry, the subscript letters didn't carry over properly from MS Word.)

 

EDIT: Also, how would you write decomposition? For example:

 

Acetaldehyde (CH3CHO) decomposes to form methane (CH4) and carbon monoxide. Write the formula equation.

How would I write "decomposes"?

[insane_alien]

you first equations is fine although you should probably write calcium carbonate as 2CaCO3 then realise that you have a 2 infront of everything and then ditch it. to get CaCO3 + heat > CaO + CO2

 

the decomposition is just represented by the arrow. its just treated as any other reaction.

[Cap'n Refsmmat]

[ce]CaCO3 ->[{\Delta}] CaO + CO2[/ce]

 

is what you'd do for heat. The delta symbol represents heat in a reaction. If you have a catalyst or something involved, it would go there as well.

 

"Decomposes" doesn't have to be written -- just write the reactants (well, there's only one), an arrow and the products.

[Toadie]

Ah, yeah that makes sense. Thanks!

[hermanntrude]

it's perfectly acceptable to write "heat" as a product or a reactant in order to indicate an exothermic or endothermic reaction respectively.

 

The delta on top of the arrow is also good but it's harder to correlate with what you'd do in the case of an exothermic reaction.