[rakesh219]

Ok the question is some what difficult. I know there are certain rules like

a. A + B = AB (combination)
b. AB = A + B (decomposition)
c. AB + C = CB + A (substitution)
d. AB + CD = AD + CB (metathesis)

to follow when trying to determine the outcome of a chemical equation

Now the trouble i have is not in balancing the equation but figuring out what the outcome of the reactants will be.

For example an unsolved and unbalanced equation.

___Ca(s) + ____H2O(l) ----> ()

Why is the answer to the above question Ca(s) + 2H2O(l) --> Ca(OH)2 + H2 and not Ca(s) + H2O(l) --> CaO + H2...

Would the following equation be right or wrong based on the 4 equations i mentioned above

___Al(s) + ____H2O(l) ----> ()

result: 2Al + 3H2O ---> Al2O3 + 3H2

Also is there anything to do with classification of elements (alkali, alkali earth, halogen, mental, non-metal, etc) on the reactant side that change the out come of the product.

Thanks!!!

[Borek]

Why is the answer to the above question Ca(s) + 2H2O(l) --> Ca(OH)2 + H2 and not Ca(s) + H2O(l) --> CaO + H2

It is all about properties of elements and substances.

Note, that your second reaction won't stop at CaO. What happens to CaO in the presence of water?

[rakesh219]

Ohh i get it. CaO would turn to Ca(OH)2. Do you know any site i could refer regarding properties of elements it would be very helpful....Thanks

[Borek]

You may start with wikipedia, but most likely your textbook contains enough information. Just remember to use not only info on particular elements, but also information from periodic table.