Chemistry HELP needed in understanding reactions.?

Question

hi there

my question is when you are asked to give an ionic equation and observation of a chemical reaction, how do you know what the observations will be?

i know how to do the ionic equations but how are you ment to know the observations?

are there any tips or hints people know that can help me piece together the observations.

thankyou in advance and ur answers are very much appreciated.

Answer 1

When you have a "bunch" of ions present in solution and one combination of them will produce an insoluble product then you have a chemical reaction, which is indicated by the formation of an insoluble precipitate.  These kinds of reactions are usually double replacement reactions.

In order to determine if a reaction occurs, you rearrange the ions to produce two products.  Then check each of those against the solubility rules to see if either is insoluble.  If one is, then you have a reaction and that one will be writtin as "a molecule" in the ionic equation.  If neither is insoluble then you end up with the same four ions you started with and there is no reaction.

Examples

NaCl(aq) + KOH(aq) -->  NaOH + KCl

Predict the products and then check the solubility rules.  Both NaOH and KCl are soluble in water.  There is no reaction.

Na+ + Cl- + K+ + OH- --> Na+ + OH- + K+ + Cl-

But if NaCl reacts with AgNO3 ...

NaCl(aq) + AgNO3(aq) --> AgCl(s) + NaNO3(aq)

Predict the products and check the solubility rules. Silver chloride is insoluble and will precipitate as a solid.

Na+ + Cl- + Ag+ + NO3- --> AgCl(s) + Na+ + NO3-