Hi,

Question

Is the molecular formula different when it is in a gaseous state?

Cheers ;)

Sometimes yes, sometimes no. H2O, for example, is thought to be in a group of 6 as a liquid at room temprature, a group of 4 at higher temperatures, and single H2O molecules as steam.

Thanks,

Ive got to determine the molecular formula of oxide of srsernic in the gaseous state?

Will it be different then?

Cheers ;)

I don't know that much about the chemistry of arsenic oxide but I am guessing from some problems I have seen posted that it is different. But I can help with the formula if you need help when you get to that point.

wot would the non gaseous formula be? would it be As2O5? is that the rite formula ive used for molecular formula?

Arsenic has a valency of 5 and oxygen -2.

Does that sound rite?

Thanks;)

im also asked y the molecular formula of a gas is not necssarily the same as the empirical formaula!

Any ideas?

;)

I'm a little confused by the single y in the question. However, the molecular formula of a gas is not necessarily the same as the empirical formula. That is a true statement. Sometimes they are different.

sorry, i put y instead of why!

Do u know why they differ?

;)

Arsenic(V) oxide usually is written as As2O5. Arsenic(III) oxide usually is written as As2O3. The data I have seen posted pertaining to the empirical formula of arsenic and oxygen suggests BOTH a monomer and a dimer so I would need the data to know which problem you are working with. As to why, often it is the result of the monomer not having enough electrons. For example, cyanogen has a empirical formula of CN but it's molecular formula is (CN)₂. That is because C has 4 electrons and N has 5 electrons for a total of 9 which leaves an uneven number of electrons and no matter how hard we try to draw the Lewis electron dot structure, we can't get eight electrons around it with an odd electron in the way. So it forms the dimer (two of the CNs together). That give us 18 electrons and they are arranged like this :N:::C:C:::N: In the case of the water molecules, which I used as an example in this same post earlier, the clusters of 6 or 4 form at lower temperatures (a H bonding kind of thing) but at the temperature of steam, there is enough kinetic energy to break those bonds and we get the monomer of HOH. I know this may not explicitly answer your question but it gets close, I think.