## Homework Problem 9C 3a

CNourian2H
Posts: 106
Joined: Fri Aug 30, 2019 12:16 am

### Homework Problem 9C 3a

So the problem asks to write the formula for potassium hexacyanidochromate(III)

I understand how to get the formula from this coordination compound name but I want to clarify a few things.

1)the -3 charge for hexacyanidochromate is not written outside the brackets bc it cancels out with the +3 charge of K, right?

2)why do we write -ido at the end of cyanide? i thought it would just be cyano bc you take out the -ide and make it -o.

3) why is it chromate? Chromiumate sounds weird, but I dont know the reason for cutting the -ium out of chromium to make it chromate.

Laura WM 3I
Posts: 31
Joined: Wed Sep 18, 2019 12:19 am

### Re: Homework Problem 9C 3a

For your second question, I believe that cyanido is just a new name convention. Professor Lavelle posted on the class website a "naming coordinate compounds" sheet. This sheet lists cyanido as a new convention, but I'm pretty sure that both cyano and cyanido will be accepted for the exam.

Melvin Reputana 1L
Posts: 55
Joined: Sat Aug 17, 2019 12:16 am

### Re: Homework Problem 9C 3a

To answer your third question, one of the naming rules for a coordination compound is that if the overall complex has a negative charge, then you add the suffix -ate to the end of the metal's name. This causes some issues for some metals like iron, where you would use the name ferrate (from Iron's latin name, ferrum) because ironate sounds weird. However, for 9C.3a, you would just follow the rule as normal and change chromium to chromate because the complex's overall charge is -3.