Chemical formula

[cheungcheung]

When we write chemical formula, such as

water+sodium hydroxide

H2O+NaOH, if we don't know the product , can we still

have the correct answer?

[java]

Yeah you can have the correct answer but you would have to examine the formula in depth. You would have to break down the water and the sodium hydroxide and take it back into the very basic form. If forget the method that you have to use to find the product. I think it is the combination method if I can recall. But its not that hard to find. I will back track into my chemistry text book and get back to you as to how to actually find the product. All i know is that it is possible to find the product just with that formula.

 

Java: Neerje

[greg1917]

When we write chemical formula' date=' such as

water+sodium hydroxide

H2O+NaOH, if we don't know the product , can we still

have the correct answer?[/quote']

 

Not sure I follow - for a start, the reaction you name there will only lead a solution of NaOH. Do you mean predict the product by only knowing the reactants?

[java]

Not predicting, there is a formula that u can use to figure out the end product. I just forget what the formula is. Once i find out the formula, i will let u know. I hope this helps alittle bit.

 

Java: Neerje

[YT2095]

does he mean the Ion charges like Na+ and OH- in water?

disasociation ?

[QuarkQuarkQuark2001]

I think he wants to ask how to predict the product which will be formed.

Actually, I want to ask

[YT2095]

Hmmm... I think in that case that the example given wasn`t a very good one, and that`s what`s made this all a little confusing, because water and NaOH dont have a product as there`s no Chemical reaction take place.

we`re working on those 2 literaly

 

but yes, to answer the question, without knowing the product, but knowing the 2 reactants we can certainly work out what that product will be

[QuarkQuarkQuark2001]

Hmmm... I think in that case that the example given wasn`t a very good one' date=' and that`s what`s made this all a little confusing, because water and NaOH dont have a product as there`s no Chemical reaction take place.

we`re working on those 2 literaly

 

but yes, to answer the question, without knowing the product, but knowing the 2 reactants we can certainly work out what that product will be [/quote']

 

How ? would you tell me ?

[YT2095]

well if we stick to your example NaOH, that is made up of 2 reactants, Na (Sodium) and an OH (Hydroxide ion).

 

well we can already see one that sodium is present, we need a source of OH, we know that water is a good source as its formula is H2O that`s 2 parts hydrogen and one part Oxygen. we only need one of each though?

 

Na + H2O = NaOH but were does the other Hydrogen go? we cant just ignore it

so it becomes:

Na + H2O = NaOH + H

 

we see that H come off as a gas when we react sodium with water, sometimes the reaction gets very HOT and the H burns off in the air.

 

this is only a simple example, but the same principal applies to all reactions

[apathy]

the only way to predict the products in a reaction is to work from what you know, but just looking at a couple of chemical formulas, you can't honestly predict the reactants, a priori. You have to already know something about the reaction, or a reaction that is similar to it.

 

Say, when learning organic chemistry, you are usually taught about classes of reactions and what they do, and then they give you a test that asks you to predict the products based on what you learned in class. But if you were to be given the chemical formulas for some reactants and be asked to predict the outcome of the reaction with no prior knowledge then that would be very difficult.

 

Nowadays, though, there are computational methods that can simulate all the wavefunctions, etc. involved and calculate the relative energies of certain molecular configurations and whatnot, and that can be a way to predict the product of a reaction, but doing that on anything but very simple systems becomes quite a task.

Then after all that, it's usually an approximation so you still can't be 100% sure.

[YT2095]

agreed, working backwards can be difficult. but when given 2 reactants it`s not that hard to work out what the product will be in a simple redox

[AtomicMX]

.... sure you can... that's the principle of finding new products (organic chemistry) with different sintesis and reaction mechanisms.