Sciencemadness Discussion Board - Is this formulae correct?

Is this formulae correct?

NEMO-Chemistry - 13-8-2016 at 12:37

I am trying to teach myself the basics, i have a book that was used for the old GCSE course in England (brought from ebay).

It was designed to be used in conjunction with the BBC bitesize website.

Keeping in mind the BBC is supposed to be reputable and is used by schools, so i kind of trust what it says.

However i am getting stuck on basic formulae and while going through some of the pages i came across something that has completely thrown me.

I cant do latex so i will give a screen shot of the bit i mean, the formulae is for Iron(II) Nitrate and the table shows the number of each atoms of the elements in it.

To me it seems wrong, if it isnt wrong then i really am not going to get this at all!

Having been working through the site i would have thought the two examples in the pic would be....

Fe(OH)3

To me should be, 1 Iron Atom, 3 Oxygen Atoms, 3 Hydrogen Atoms.

The site shows in the table 1 Iron Atom, No Oxygen Atoms?? And 3 Hydrogen Atoms!

The next one is the Iron(II) Nitrate

Fe(NO3)2

To me this should be 1 Iron Atom, 2Nitrogen, 6 Oxygen and no Hydrogen Atoms.

I dont understand how they have

1 Iron, 2 Oxygen Atoms and 6 Hydrogen Atoms and NO Nitrogen atoms??

The page is here http://www.bbc.co.uk/schools/gcsebitesize/science/ocr_gatewa...

I appreciate this is completely basic stuff, but if i am wrong and they are right then i dont understand how it works at all!

If they are wrong then in some ways that is worse, how am i supposed to learn when a site used in teaching basic chemistry in schools is completely wrong.

Its embarrassing to even ask the question, but can someone tell me please if its me being utterly thick or the site being shit!

Really sorry to ask this kind of question but i am trying my best to teach myself, and the periodic table and formulae are my major PITA sticking points, if i can crack that i feel i stand a chance in learning chemistry. Instead of simply copying reactions etc as i am doing currently.

I appreciate any help.

blogfast25 - 13-8-2016 at 14:50

The formulas are correct but the atom counts are wrong. I suspect a formatting error to be the cause.

Fe(OH)₃= 1 x Fe + 3 x H + 3 x O

Fe(NO₃)₂ = 1 x Fe + 2 x N + 2 x 3 x O

Well spotted. You're not going mad!

NEMO-Chemistry - 14-8-2016 at 02:59

Quote: Originally posted by blogfast25

The formulas are correct but the atom counts are wrong. I suspect a formatting error to be the cause.

Fe(OH)₃= 1 x Fe + 3 x H + 3 x O

Fe(NO₃)₂ = 1 x Fe + 2 x N + 2 x 3 x O

Well spotted. You're not going mad!

Thanks for that!! It had me in a panic! At least i know i am on track! I should have known an UK education site was going to have errors in lol.

I was going to chuck my glassware had they been right

AJKOER - 18-8-2016 at 14:53

I personally dislike chemical educational texts that focus on simplistic reductionism at the actual expense of the underlying inconveniencely complex truth. For example, take the reference to Fe(OH)3, I would argue one would be hard pressed to prepare pure Fe(OH)3. Some actual science to quote from Wikipedia on iron(III) oxide-hydroxide (link: https://en.m.wikipedia.org/wiki/Iron(III)_oxide-hydroxide ) as there is no dedicated Wikipedia page to Fe(OH)3:

"A number of chemicals are dubbed iron(III) oxide-hydroxide. These chemicals are oxide-hydroxides of iron, and may occur in anhydrous (FeO(OH)) or hydrated (FeO(OH)·nH2O) forms. The monohydrate (FeO(OH)·H2O) might otherwise be described as iron(III) hydroxide (Fe(OH)3), and is also known as hydrated iron oxide or yellow iron oxide."

For example, assume one reacted anhydrous FeCl3 with pre-heated NaOH (to drive out the water) as follows:

FeCl3 + 3 NaOH → FeO(OH).H2O + 3 NaCl

As the ferric chloride is very acidic upon reacting with a strong base, a lot of heat is generated. As such, even this carefully constructed reaction is not likely to produce pure FeO(OH).H2O (or, Fe(OH)3 ) as some of the water would be driven off in the exothermic reaction producing a mixed iron(III) oxide-hydroxide.

Solution: A better example would be Al(OH)3, for example, which at least has a Wikipedia page.

[Edited on 18-8-2016 by AJKOER]

NEMO-Chemistry - 18-8-2016 at 15:56

Interesting you have wrote this.

Today after reading for a while and redoing some simple things i have been upto, i came to the conclusion that you have to learn chemistry 2-3 times.

My experience so far has been one of not having the faintest idea of how to predict , or even tell if one will happen. So i ask questions and read links, then i get a couple of simple text books and they kind of give you a starting point.

So i am starting to understand in simple terms that molecules want to do what it takes to fill there outer shell (in really basic terms).

This kind of at least makes it possible to have a stab at what the chemical formula is in words and what the product of a reaction would be.

Then you delve into Blogfasts thread, and you discover that actually the electrons are not nice and neatly going around in a circle, its almost like some might meet and pair up and some might not (again i am way way over simplifying).

I also have a book on valence theory! Now that at the moment is utter gobbly gook!! Not a single words makes any sense.

So i am 'doing' things from books and trying stuff out (i try and at least make sure its pretty harmless). The basic books are helping me establish a point at which to start, i am however aware that once i have got to grips with that I will have to tackle Blogfasts thread!

That will mean taking the simplistic knowledge i am gaining and learning the reality.

From there i can if i am bright enough start to learn the heavy duty stuff! Blogfasts thread goes over my head alot of the time, but very slowly day by day i understand a tiny fraction of it a little more.

So to me chemistry is something you kind of learn 3 times, you learn the nealry right but simple view, this gives you a rough guide or direction, then you study the level Blogfast has posted to learn the reality and the fact that the simple approach just isnt reality.

Then my choice will be am i happy to stay with a good grounding or do i want to take it all the way.

Chemistry like many things comes easy to some and hard to others, i am not sure where i fit, its not coming easy for sure. But with work i am slowly gaining small chinks.

I can see where you coming from, i expect once i have learnt far more then i might look at the simple texts with disbelief almost, but for now i think they serve a purpose and have a place, with the caveat i am starting to think you need to read them knowing that what they are saying is massively simplified and not exactly how it really is.

NEMO

Deathunter88 - 18-8-2016 at 20:54

I think you should enroll in an online AP chemistry course. Not the ones that are self paced, but one where there is a schedule and you have to turn in labs, work, problem sets etc. Most importantly, an actual teacher grades your work so you can get feedback.

NEMO-Chemistry - 19-8-2016 at 00:33

Quote: Originally posted by Deathunter88

I think you should enroll in an online AP chemistry course. Not the ones that are self paced, but one where there is a schedule and you have to turn in labs, work, problem sets etc. Most importantly, an actual teacher grades your work so you can get feedback.

I will see if i can find one and how much they are. cheers! I didnt know they existed. I am at secondary school (USA high school equiv i think).

NEMO-Chemistry - 20-8-2016 at 14:11

Found the Royal Society for chemistry website! Learning wise its just what i was looking for, i can practice titration's etc online without wasting a drop of chemical!!

Then once i get a decent score i can toodle off and do it for real, but seriously its really good for learning the basics, maybe...just maybe, i might actually learn this chemistry stuff