Acid-Base reaction help!

[TrueTears]

There is this question which says: Write a chemical equation for the reaction between nitric acid and magnesium carbonate.

I know how to do this, except that I'm not sure whether the steps I'm following are correct. (My teacher never taught us this and i had to self-learn). So if anyone can show me an exact step by step process to tackle these acid-base reactions that would be awesome!

The way i approach these are: there are 6 reaction types which are listed in my book, i first find which reaction type the reaction is and then follow the process. Eg, Magnesium carbonate and nitric acid follows the Acid + metal carbonate ---> Salt + Water + Carbon dioxide, reaction type.

So we have HNO3 (aq) + MgCO3 (s) ----> salt + H2O (l) + CO2 (g)

then i always balance the H atoms first. So equation becomes: 2HNO3 (aq) + MgCO3 (s) ----> salt + H2O (l) + CO2 (g)

Then to work out what the salt is, i 'cancel' out the atoms which are both sides of the equation: So the 2H from 2HNO3 cancels the 2H from H2O. The C from MgCO3 cancels out the C in CO2. There are 3O's in MgCO3 which 'cancel' out the 3O's on the right hand side (1 from H2O and 2 from CO2). So then we are left with 2NO3- and Mg+. So the salt is Mg(NO3)2

Therefore the equation is 2HNO3 (aq) + MgCO3 (s) ----> Mg(NO3)2 (aq) + H2O (l) + CO2 (g)

Is this the way to approach these kinds of questions? ie, finding the reaction type, then 'canceling' the same atoms on both sides of the equation to find the salt. If not, can anyone list how they would approach this question, and acid-base reactions equations in general?

Many thanks!

[mystikal]

hrmm i dont understand about this canceling business but this is how i was taught to approach theses questions. Basically there are rules which are in your textbooks which state Acid + metal carbonate ---> Salt + Water + Carbon dioxide, reaction type.

So in this case
 HNO3 (aq) + MgCO3 (s) ----> salt + H2O (l) + CO2 (g)
You already know that regardless of the result you indeed need to have H20 and C02
You also know that Mg and N03 are gonna go together because they just have to therefore you just write out the straight forward answer.
HNO3 (aq) + MgCO3 (s) ----> Mg(NO3)2 (aq) + H2O (l) + CO2 (g)
Then you balance it .
2HNO3 (aq) + MgCO3 (s) ----> Mg(NO3)2 (aq) + H2O (l) + CO2 (g)

hope this helps its really hard to explain online

[TrueTears]

yeah i kinda get it, but why does Mg have to go with NO3? eg, if you have another type of acid-base reaction, lets say when CaO is reacted with HNO3. Why is the salt Ca(NO3)2. Is there a systematic way to find what the salt is?

[dekoyl]

You can do it by "cancelling down". As for WHY they go together, I guess it's just all about the Bronsted Lowry Theory. I'm not that good with chemistry


We know Acid + Metal Oxide = Salt + Water

So you know that there's going to be

where x is the salt. I put a 2 in front of the nitric acid because it only has one hydrogen and you know water needs two.

So now there is:

as others have been used.

Is a possible salt.
(1 Ca, 2 N, 6 O)

I'm terribly sorry if it's wrong. Maybe Coblin can answer your question clearly if he comes around.

[TrueTears]

You can do it by "cancelling down". As for WHY they go together, I guess it's just all about the Bronsted Lowry Theory. I'm not that good with chemistry


We know Acid + Metal Oxide = Salt + Water

So you know that there's going to be

where x is the salt. I put a 2 in front of the nitric acid because it only has one hydrogen and you know water needs two.

So now there is:

as others have been used.

Is a possible salt.
(1 Ca, 2 N, 6 O)

I'm terribly sorry if it's wrong. Maybe Coblin can answer your question clearly if he comes around.

yeah thanks, that's the way i approach it as well. Just wondering if there was any other way to do it