# Is there such a formula

1. Feb 21, 2010

### simhank

Everyone keeps telling me I am writing this formula down wrong but it is one my teacher gave to figure out....am I wrong and what formula name is it???

Mg3(PO5)2

Also not sure what chemical formula for these two are any help would be great

1. Chlorhydric acid
2. Iodhydric acid

2. Feb 21, 2010

### samblohm

It is suppose to be Mg3(PO4)2. Notice the 4 instead of 5. There is no such thing as the acids you mentioned. I think you mean Hydrochloric and Hydroiodic acids, they are HCl and HI

3. Feb 22, 2010

### E=mc^84

You shud write the 2 molecules in their ion form, it will help you to write the formula out right: Mg+2 + PO4^3- = Mg3(PO4)2, use the criss-cross rule especially when working with polyatomic ions. Also, the there are only 2 forms PO4^3- and PO4^2-.

Those acids are just common industry names for HCl and HI.

Hope this helps :)

4. Feb 22, 2010