Chemical Forums
Chemistry Forums for Students => High School Chemistry Forum => Topic started by: DarkLightA on November 19, 2009, 04:20:02 PM
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I'd really, really, really appreciate it if someone read through the following any commented on any mistakes, bad thinkings etc. I know it's a medium-long read, but I would be forever thankful!!!!!
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So, I know the following rules:
1. Acid + Alkali ==> Salt + water
2. Acid + Metal ==> Salt + hydrogen
3, Acid + Metal Carbonate ==> Salt + CO2 + H2O
[4. Metal + H2O ==> alkali (? Like KOH, is that an alkali? We learnt that metal oxides are basic.) + Hydrogen]
Examples of my thinking:
1. Alkali + Acid ==> Salt + Water
NaOH + HCl ==> NaCl + H2O
and since NaCl has a valence of 0 (do you call it valence in compounds?) it works.
But, for something like CaO + HCl:
CaO + HCl ==> CaCl + OH
There's obviously missing an H there, so we add it from the only term of CaO and HCl with H in it:
CaO + 2HCl ==> CaCl2 + H2O
And CaCl2 has valence 0, so it works.
2. Acid + Metal ==> Salt + hydrogen
K + HCl ==> KCl + H
It has to be H2, so:
K + 2HCl ==> KCl2 + H2
KCl2 would have a + valence, so it wont work, however:
K2 + 2HCl ==> 2KCl + H2
And that has a valence of 0, so it works.
Other example:
Ca + HCl ==> CaCl + H
Has to be H2:
Ca + 2HCl ==> CaCl2 + H2
CaCl2 has valence 0 so it's perfect =)
3. Acid + Metal Carbonate ==> Salt + CO2 + H2O
HCl + K2CO3 ==> K2Cl + CO2 + H2O
That seems right to me: K2Cl is a happy compound with full shells.
HCl + CaCO3 ==> CaCl + HO + CO2
Okay, there's obviously a problem with H2O here, we're missing a H.
2HCl + CaCO3 ==> CaCl2 + H2O + CO2
And this seems good. CaCl2 is happy!
4. Metal + H2O ==> alkali + hydrogen
K + H2O ==> KOH + H
but you can't just have H, you have to have H2, so:
K + 2H2O ==> K(OH)2 + H2
But K(OH)2 isn't "happy", as it has a valence of +, but an extra K would fix that:
2K + 2H2O ==> 2KOH + H2
and that seems good.
But how about:
Ba + H2O ==> BaOH + H
Has to be H2..
Ba + 2H2O ==> Ba(OH)2 + H2
and then that looks good.
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No such things as valence in compounds, no idea what you refer to.
Surprisingly, your reactions are balanced OK. Usual approach is to decide formulas first, balance later.
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I read through them (but didn't check your balanced equations) and from the reactants and products everything looks fine to me.
**Except the following**
For #3 it should be:
K2CO3 +2HCl → 2KCl + CO2+ H2O (Remember, K2 is not part of K, it is the charge of CO3)
I'm not positive for the very last one with Ba and H2O!
P.S. You can usually find these through google also.
Hope this helps :)
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Well, you may want to ask Borek or a professional handler of chemicals to check K2CO3 since above he says that they looked okay.
I think it should be this though - although I may be wrong! :-X
Ask Borek, he'll know.
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Nah, you are right - K2Cl is wrong. My mistake. I have just skimmed and missed it. I have also missed K2 instead of 2K in #2.
Should not check such things at 1 am.
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Whoa! I beat Borek at something. :P :P :P
Mmm...let me just take this moment in. ;D (Kidding)
Time differences are big from you to me! It's only 7:00 P.M. here!
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Nah, you are right - K2Cl is wrong. My mistake. I have just skimmed and missed it. I have also missed K2 instead of 2K in #2.
Should not check such things at 1 am.
This is where my thought of "valence" comes in:
K2Cl is 2 K, element 19, and 1 Cl, element 17. Add it together: 38+17=55, and that's one OVER the 54 "noble" value. So you have to get 1 more under, which would work with chlorine, so it has to be:
2KCl
I think this works =D
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I think this works =D
Only sometimes. NaCl is 11+17=28, nowhere near "noble values" of 10, 18 or 36.
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I think this works =D
Only sometimes. NaCl is 11+17=28, nowhere near "noble values" of 10, 18 or 36.
Okay, I realize this now, but I don't tend to do it with atomic numbers but rather valence. Then it seems to work every time =) Including NaCl.
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K2CO3 +2HCl → 2KCl + CO2+ H2O (Remember, K2 is not part of K, it is the charge of CO3)
That's what I wrote, but I didn't have subscript, sorry.
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About the Ba + H2O, I found the following:
Ba(s) + 2H2O(l) ---> Ba(OH)2(aq) + H2(g)
Thanks for all your *delete me*
"DLA"
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NaOH(aq) + HCl(aq) ==> NaCl(s) + H2O(l)
CaO(aq) + 2HCl(aq) ==> CaCl2(s) + H2O(l)
K2(s) + 2HCl(aq) ==> 2KCl(s) + H2(g)
Ca(s) + 2HCl(aq) ==> CaCl2(s) + H2(g)
HCl(aq) + K2CO3(s) ==> K2Cl(s) + CO2(g) + H2O(l)
2HCl(aq) + CaCO3(s) ==> CaCl2(s) + H2O(l) + CO2(g)
2K(s) + 2H2O(l) ==> 2KOH(aq) + H2(g)
Ba(s) + 2H2O(l) ==> Ba(OH)2(aq) + H2(g)
is this correct?
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but I don't tend to do it with atomic numbers but rather valence. Then it seems to work every time =) Including NaCl.
Please elaborate, again it is not clear what you mean.
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CaO(aq)
K2(s)
K2Cl(s)
These are wrong, for various reasons.
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but I don't tend to do it with atomic numbers but rather valence. Then it seems to work every time =) Including NaCl.
Please elaborate, again it is not clear what you mean.
Sorry, I realize I've made a mistake. I meant the ions it forms.
For example:
CaOH has two parts: Ca and OH.
O makes -2 ions.
H makes +
Together, -2+1=-1
So I say that OH has an "ionic charge" of -
Ca is simple enough: 2+
+2-1=+1
It has to be 0, so we need another - somewhere.
Looking back, OH is -, so by adding another of them it'll be 0:
Ca(OH)2
Ca: 2+
OH: O: 2- H: + TOTAL: -
OH: O: 2- H: + TOTAL: -
So +2-1-1=0 and that works.
Example 2:
BaCl
Barium makes 2+
Chlorine makes -
Together, +2-1=+1
So to make it 0, we need another -. This can be found in Cl, so we add one of them:
BaCl2
And there:
Ba: +2
Cl: -
Cl: -
In total: +2-1-1=0, so it's happy.
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CaOH has two parts: Ca and OH.
I would put it "calcium hydroxide has two parts" - CaOH doesn't exist (or at least at this stage you have no idea if it does or not).
O makes -2 ions.
H makes +
Together, -2+1=-1
So I say that OH has an "ionic charge" of -
That's not bad, but dangerous - sooner or later you will hit element that can have several valencies and it won't be that easy. Besides, OH- is not a compound made of two ions O2- and H+ - it is "just" OH-.
Ca is simple enough: 2+
+2-1=+1
It has to be 0, so we need another - somewhere.
Looking back, OH is -, so by adding another of them it'll be 0:
Ca(OH)2
Molecule must be neutral, so if we know that calcium cation has charge +2 and OH group -1, it must be Ca(OH)2. OK
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O makes -2 ions.
H makes +
Together, -2+1=-1
So I say that OH has an "ionic charge" of -
That's not bad, but dangerous - sooner or later you will hit element that can have several valencies and it won't be that easy. Besides, OH- is not a compound made of two ions O2- and H+ - it is "just" OH-.
It seems like it works for everything without metals from groups 3-12 (transitionals)
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I'm sure you could find multiple other exceptions that this would not work for...
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Like - what is formula of carbon oxide? Nitrogen oxide? Phosphorus oxide?
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Like - what is formula of carbon oxide? Nitrogen oxide? Phosphorus oxide?
Those aren't part of my 4-step list..
1. Acid + Alkali ==> Salt + water
2. Acid + Metal ==> Salt + hydrogen
3. Acid + Metal Carbonate ==> Salt + CO2 + H2O
4. Metal + H2O ==> alkali + Hydrogen
And I'm talking about using that method to find output, not input. Btw, you don't really hear much about CO, but CO2, which has an ionic charge of 0.
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There are two oxides of carbon
Carbon Monoxide CO
and
Carbon Dioxide CO2
Borek knew exactly what he was talking about when he gave his examples and there are many others where you simplistic approach breaks down. That was what he was telling you; learn the real rules behind chemistry rather than making up your own that work initially but then cause you more problems later on. Now from your thread about your teacher we know your chemistry teacher doesn't know very much chemistry (probably because they do not have any qualifications in chemistry) so we'll try to help you. But you need to listen to what we say because we do know more chemistry than you. Borek knew where your approach would fail and tried to steer you away from it. Both Borek and I have been qualified chemists for longer than you have been alive. If you are really interested in chemistry buy some of the starter text books listed on the good chemistry books threads. Read them and then ask questions here. The problem with trying to learn these things by searching the web is you'll find articles aimed at higher levels than you are ready for. Things are deliberately simplified at your level so you do not get overwhelmed then as you learn more and more things get more and more complicated as you get closer to reality.
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There are two oxides of carbon
Carbon Monoxide CO
and
Carbon Dioxide CO2
Borek knew exactly what he was talking about when he gave his examples and there are many others where you simplistic approach breaks down. That was what he was telling you; learn the real rules behind chemistry rather than making up your own that work initially but then cause you more problems later on. Now from your thread about your teacher we know your chemistry teacher doesn't know very much chemistry (probably because they do not have any qualifications in chemistry) so we'll try to help you. But you need to listen to what we say because we do know more chemistry than you. Borek knew where your approach would fail and tried to steer you away from it. Both Borek and I have been qualified chemists for longer than you have been alive. If you are really interested in chemistry buy some of the starter text books listed on the good chemistry books threads. Read them and then ask questions here. The problem with trying to learn these things by searching the web is you'll find articles aimed at higher levels than you are ready for. Things are deliberately simplified at your level so you do not get overwhelmed then as you learn more and more things get more and more complicated as you get closer to reality.
Neither is part of an input for any of the formulas my method works for.
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If you are really interested in chemistry buy some of the starter text books listed on the good chemistry books threads.
This is the best advice DarkLightA. The internet may be free, but the information is largely fragmented, and it is not as helpful as reading and working through a general chemistry book that is designed to take you through the subject step by step and build your knowledge in the proper way. I know that there is that feeling that your teacher isn't providing for you and there may be a bit of that youthful rebellion in you that if you have to teach yourself, you might as well throw out *all* authoritative sources on the issue. However, you *do not* have to reinvent the wheel. Working through a good introductory book will help you build a workable knowledge of the subject that is consistent with the way other people are being taught.
Having a knowledge base that is consistent with the way others are being taught is *extremely* important in chemistry. Without it, we simply can't communicate with one another. My main criticism of your teacher's equations is not that they are inaccurate (his equations ARE still accurate in an empirical sense), but rather that this is not the way people are being taught how to write an equation. So people that learn it your teacher's way will be isolated from the other chemists and won't be able to share ideas or build future knowledge in a useful way.
If you want to just make up new rules as you go (like these formulas you are working on), I predict that you will end up just as off base as that teacher is some day, and is THAT what you really want? To become what you are criticizing? (Ooh, it's so Luke Skywalker and Darth Vadar like!). So get a book that conforms to accepted standards and work through it ;) The closer you adhere to the standards and rules in a standardized chemical text the better off you will be on standardized tests, on coursework in future classes, and in future correspondence with other chemists. Trust me on this. I know that youthful rebellion boils in you, but modern science is no place for lone rangers...
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Neither is part of an input for any of the formulas my method works for.
If you prefer to be stubborn - use your methods. We can't forbid you to do it. As we tried to point to you several times - don't be surprised when you hit the wall.
Here is a book that you can download for free:
http://preparatorychemistry.com/Bishop_versions.htm
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Okay, I'll have a go at some books :D
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Good, when you have found one you like and worked through it if you have more questions come back and ask us to help.
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Is this good for me? Or is it too advanced? http://www.amazon.com/exec/obidos/ASIN/0486656225/thechemicalfo-20/104-3671508-3002355?_encoding=UTF8&camp=1789&link_code=xm2
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Is this good for me? Or is it too advanced? http://www.amazon.com/exec/obidos/ASIN/0486656225/thechemicalfo-20/104-3671508-3002355?_encoding=UTF8&camp=1789&link_code=xm2
Great book to begin with.
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Is this good for me? Or is it too advanced? http://www.amazon.com/exec/obidos/ASIN/0486656225/thechemicalfo-20/104-3671508-3002355?_encoding=UTF8&camp=1789&link_code=xm2
Great book to begin with.
Are you sure it won't be too hard?
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Is this good for me? Or is it too advanced? http://www.amazon.com/exec/obidos/ASIN/0486656225/thechemicalfo-20/104-3671508-3002355?_encoding=UTF8&camp=1789&link_code=xm2
Great book to begin with.
Agreed!
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Are you sure it won't be too hard?
Parts of it are very challenging, yes. Since you are in the 8th grade this may not be the best introduction for you at this point. It IS a book that you will want to read cover to cover one day though so don't forget it (I read it as a junior in college...this book will do more for you than a dozen university level courses). I recommend trying this book at your level:
http://www.amazon.com/Chemistry-Easy-Way-Barrons/dp/0812091388
It is not really an "Easy Way" book (which is why it is criticized), but rather it is a how to prepare for High School Standardized Tests in Chemistry book (the easy way name got slapped onto it as a marketing ploy because the "dummies" books were so financially successful). Still, it has a good balance of being low cost, simple enough for a beginning student, and yet challenging enough not to be a complete waste of time like most of the other beginner books out there. And because it used to be a how to prepare for standardized tests book, there are MANY problems and even a final exam at the end to allow you to measure your progress. I worked through this book when I was starting out with chemistry, and so I can certify that it works ;)