# Homework Help: Trivial question about chemical rxns

1. May 26, 2008

### Moe*

I don't really get how chemical rxns are formed....sad but Le true

If you have the compound Na$$_{}2$$CO3 dissolved in water how do u know whats formed?

B)How do u know soluble it is/if it is an acid or base?

Last edited: May 26, 2008
2. May 26, 2008

### Ed Aboud

Well I suppose you become familiar with a lot of reactions.
For example sodium carbonate breaks down into Na+ and CO3- ions.
To tell if its an acid or base you look at its acidity constant, basically how much the original substance breaks or dissociates. A large value of this constant will indicate that it is a strong acid.
Like wise you would do the same to tell how basic something is.

Last edited: May 26, 2008
3. May 27, 2008

### Moe*

Ok that makes alot of sense but instead of a clear dissociation what if u had a Cu + HNO3....>
how do u know exactly which reaction is correct (Cu(No3)2 +2NO2 )/ Cu(NO3)2 +2No2 +2H20 with the HNO3=4HNo3 for balancing..?

4. May 29, 2008

### Kushal

there exists different types of reactions. (Acid-Base, redox, disproportionation,...)

you took a bad example. actually copper does not react with dilute acids. It is quite unreactive. but very electropositive metals (sodium, calcium, magnesium,...) react with acids to liberate hydrogen.

copper can be reduced by conc. nitric or sulphuric acids.

you need to observe the trends in reactions. but sometimes there will be exceptions also.

have a look at the reactivity series of metals.

5. May 29, 2008

### Staff: Mentor

These react directly with water, no need for acid. If you want example of metal reacting with diluted acids go for iron or zinc.