Page 1 of 1

### 17.31d

Posted: Mon Nov 20, 2017 9:10 am
Can someone please explain step by step how 17.31d is done?

write the formula for each of the following coordination compounds: sodium bisoxalato(diaqua)ferrate(III)

Thank you!

### Re: 17.31d

Posted: Mon Nov 20, 2017 9:40 am
For sodium bisoxalato(diaqua)ferrate (III), start with the first part of the name.

Sodium's separation from the name of the compound implies that it is outside of the brackets. Na [

Then, inside of the brackets, start with the first portion of the name (this will be rearranged later). Bis implies that there are two oxalate molecules, each of which has a -2 charge. Na [(C2O4)2

Next, tackle diaqua. Again, di implies that there are two water molecules. In many cases, water is written as OH2 in these compounds. Na [(C2O4)2 (OH2)2

Finally, ferrate refers to iron. The III refers to its oxidation number, which you can calculate based on the total charge of the molecule. Thus, the total charge within the brackets is +3-2(2)=-1, which allows it to bond with the +1 charge on sodium. Na [(C2O4)2 (OH)2 Fe]

Now, rearrange the molecules in the brackets to fit the standard convention. Na [Fe (OH)2 (C2O4)2]

### Re: 17.31d

Posted: Mon Nov 20, 2017 9:43 am
Hi yes,

So these are the steps that I like to follow:

1) Identify the cation and the anion and make sure you write cation first then the anion. In this case Sodium is the cation and the anion is bisoxalato(diaqua)ferrate (III) anion.

2) Focus on writing the anion first and make sure you open brackets and put your central metal atom first: [Fe ]

3) Then write out what bisoxalato part and then the diaqua part separately; we will then put them in the brackets alphabetically ordered: [Fe(OH2)2(C2O4)2]. Also as a hint: use Greek prefixes and the other type of prefixes to help you with identifying how many ligands there are present.

4) Then put the coordination compound together: Na[Fe(OH2)2(C2O4)2]

5) to determine the charge of Fe, we know that C2O4 has a -2 charge and since there are two oxalatos, hence the name bisoxalato, there's a -4 charge on it. Then H2O of course has no charge and the iron atom has a +3 charge as indicated by the roman numeral, so overall, the complex ion has a charge of -1 and since Na has a charge of +1, the answer is: Na[Fe(OH2)2(C2O4)2].

### Re: 17.31d

Posted: Tue Nov 21, 2017 3:06 pm
Why is water written as OH2 instead of H2O?

### Re: 17.31d

Posted: Tue Nov 21, 2017 4:39 pm
Julia Meno 1D wrote:Why is water written as OH2 instead of H2O?

I talked to my TA today and he said water is usually written with the oxygen first because the oxygen is what is donating its electrons in bonding, not the hydrogen. Technically, either way of writing the formula for water is correct.