can you clarify this- Gchem?

[Dencology]

would anyone clarify this:

sometime we use 32g for oxygen (O2)when we try to figure out the limiting reagent and when it comes to calculating emperical formula, we use 16g. why is that?

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[gentile1225]

This is because when you have oxygen occurring in a reaction it occurs as a diatomic - 02 (A mnemonic I use to remember the diatomics is HONFClBri - hon fickle bree), such as in a problem using limiting reagents.

When you are calculating the emperical formula you are finding the total number of oxygens in the molecule, i.e. glucose C6H1206.

 

[Dencology]

This is because when you have oxygen occurring in a reaction it occurs as a diatomic - 02 (A mnemonic I use to remember the diatomics is HONFClBri - hon fickle bree), such as in a problem using limiting reagents.

When you are calculating the emperical formula you are finding the total number of oxygens in the molecule, i.e. glucose C6H1206.

I like the mnemonic. so when it comes to finding which is the limiting reagent in the rxn, we use the mnemonic and we find the moles of the particular element that we are trying to figure out whether it is limiting or it is excess, right?

and when it come to emperical problems like


we have 42grams of Oxygen, 55grams of Cl and the rest Hydrogen. what is the emperical formula?

so here we have to divide 42 by 16 or 32? what about Cl and H?

this is what i mean?

 

[zuma35]

In the empirical formula problems you are trying to find the number of moles of each element, not of a diatomic molecule. So you would divide by 16 for O, and 35 and 1 for CL and H.

 

[Dencology]

In the empirical formula problems you are trying to find the number of moles of each element, not of a diatomic molecule. So you would divide by 16 for O, and 35 and 1 for CL and H.

thank you zuma. well explained.

 

[gentile1225]

sorry i couldnt get back to you in time, damn psychology class!