[Kimyko]

Okay, uhm, hi? In an awkward attempt to not break the rules, I'll just give some background info; what I've tried, why I think I'm having problems, and so forth. If you just want to know what the questions themselves are, then, I suppose you could just read the bottom? Sorry if it seems too much, I do tend to ramble, I just don't want to be breaking any rules and it might help me figure out why it's so hard for me.

Anyway, I'm doing the Chemical Equations and Reactions section in my school, and for some reason, I'm just not getting it. I understand many of the rules, but these things don't 'click' with me. It's probably because I'm so shakey with the stuff we learned at the beginning and because I tend to overthink and from there, I commit academic suicide. Valences, electron configuration, figuring out how to actually make those chemicals, chemical names...all of those are a jumble to me, so I apologize if I seem idiotic. It's true that I'm fairly slow, and most of this will probably seem like first grade math, but...I just have...problems, I guess. I don't understand anything unless it's pretty much screaming the answer at me. ...Even when it does that, I sometimes can't get it.

Most of my "work" will just be mostly my thought process, the things I thought as I tried to figure out the problems. Even if you can't help, or would rather I thought it out myself, I would really appreciate it if someone told me what was wrong with the thought process itself and then walk me slowly to the answer.

I know there are a lot of questions and I really do apologize. I really don't need them all answered at once because some of them, I sort of know what the answer is, but it feels wrong or despite getting an answer, I don't think I did it right. I would really be happy if I just got a nudge in the right direction, even. I hope this isn't terribly against the rules. There's just this iffy grey area when it comes to chemistry for me, which makes it so hard to ask my teacher...especially since I feel like my questions are redundant. And, uhm, anyway, I really appreciate any kind of help that anybody can give me.

Uhm, yeah, my questions...here they are:

1. Very active metals will react with water to release hydrogen gas.

a. Complete and then balance the question for the reaction of Ca(s) with water.

My work:

Ca(s) + H₂O(l) ---->  H₂ + Ca₂0₂

Okay, here? I freeze. Ca₂0₂ does not look right. I've never seen this before. I'm pretty sure there's H₂ somewhere because it says so in the very problem.

But if I were to assume it was right, then...I would balance, I think. So...just making that assumption, then:

2Ca(s) + 2H₂O(l) ---->  2H₂ + Ca₂0₂

Is that it...?

b. The reaction of rubidium, Rb, with water is faster and more violent than the reaction of Na with water. Account for this difference in terms of the two metals' atomic structure and radius.

My work:

...I don't even know.

I would guess that it has something to do with the number of electrons in the outer shell of Rubidium in comparison to the number of elections in the outer shell of Sodium and their willingness to share with water. That's about as far as my brain got before I realized it had nothing to do with atomic structure and radius...

2. Gold is often used in jewelry. How does the relative activity of Au relate to its use in jewelry?

My work:

...What does relative activity have to do with anything? How easily it undergoes chemical reactions?

Uhm, going with the stupidest, almost sarcastic answer of them all, Gold is used in jewelry because not only is it shiny, it is practically unreactive, so people use it in jewelry because they would prefer not to have something hanging around their neck that would explode or burn their skin off or something of the like.

3. Explain how to use an activity series to predict certain types of chemical behaviour.

My work:

It seems like it would be so obvious, yet I can't help but think there's something I'm missing. The activity series tells how easily an element reacts in chemical reactions, so...using the activity series, you can figure out if chemical equations actually yield a product or not...?

That's pretty much as far as I got before I though that there was no way...

4. Aluminum is above copper in the activity series. Will aluminum metal react with copper(II)nitrate, Cu(NO₃)₂, to form aluminum nitrate, Al(NO₃)₃? If so, write the balanced equation for the reaction.

My work:

Al(s) + Cu(NO₃)₂ ----> Al(NO₃)₃ ?

This would be no, wouldn't it? Because the copper just...disappears? And if it disappears, it doesn't follow the law of conservation of mass, does it?

-----

Those were problems in my homework, and for the life of me, I can't get my brain to comprehend them no matter how much I try. Now these are actually questions having to do with balancing equations. They're from an extra credit packet which I also don't understand. I mean, I get all the rules, don't get me wrong, my brain simply can't wrap itself around the idea of doing these equations.

I apologize again for the questions, the quantity of them at least.
-----

Anyway, more questions:

1. SO₂ + H₂O ----> ?

My work:

Okay, so in my packet, it says it's supposed to be synthesis, which means that those two are supposed to come together to form one substance. But then, that means the H and the O and the S have to all make their way to the other side of the equation.

So...HSO...something?

SO₂ + H₂O ----> HSO₄

...I'm not sure which one would work, though. I vaguely remember that there existed an H₂SO₃ or...something. Which one are we supposed to pick? And then there's the issue with giving it a name. The product, I mean. (I'm trying to figure this out without a lot of help from my book, as to mimic what a test would be like so...) Hydrogen...sulfate, I would think it was.

Anyway, now, I would think I should balance.

2SO₂ + H₂O ----> 2HSO₄

...Would that be right? Now, here's a snag that I came up against. In addition to this, there was another equation which was like this: SO₃ + H₂O ----> ?

So...my question here would be, would it be the same answer? Would the balancing just be a little bit different? Or what?

2. Hg₂CO₃ ----> Hg + HgO + ____

My work:

...Nothing. I have nothing. Honestly, with these kinds of equations I draw blanks. Complete and total blanks, if there was anything I needed help with, it would probably be problems such as these. I'm not sure if I fear it, or if it's just far too hard for me.

3. Zn + H₂SO₄ ----> ___ + ___

My work:

I'm just guessing. I know about...as much as I did in the above problem. I'm clueless, but as usual, I'm going to guess it.

Zn + H₂SO₄ ----> Zn(OH)₂ + S

...I don't know how I'm supposed to have gotten this. The one element on the right, I know, is supposed to replace one of the elements in the compound and push another out...so I just assumed.

I've never quite figured out the rule with OH, or things like that. When you balance it, I mean.

But still, I don't even think it's right. Not at all.

Pb(NO₃)₂ + HI ----> ?

My work:

Pb(NO₃)₂ + HI ----> I(NO₃) + PbH₄

I have no clue how I got this. I know one is supposed to replace another depending on its place in the activity series, but...I don't know. There's no lead, no iodine, or anything. I think I'm confusing one thing with another. And then I know there are rules about how one of them, in a double replacement reaction, has to be at least a gas, water, or a precipitate.



I think this is really the basics of what I don't get. I'm sorry, I know that there is so much, and I'm asking a lot. Nobody really needs to answer them all, I just need a basic idea...some help...stuff like that. I'd really appreciate it.

[Yggdrasil]

1. Very active metals will react with water to release hydrogen gas.

a. Complete and then balance the question for the reaction of Ca(s) with water.

My work:

Ca(s) + H₂O(l) ---->  H₂ + Ca₂0₂

Okay, here? I freeze. Ca₂0₂ does not look right. I've never seen this before. I'm pretty sure there's H₂ somewhere because it says so in the very problem.

But if I were to assume it was right, then...I would balance, I think. So...just making that assumption, then:

2Ca(s) + 2H₂O(l) ---->  2H₂ + Ca₂0₂

Is that it...?

The good news: you balanced the equation correctly assuming that H₂ and Ca₂O₂ are the correct products.

The bad news: you were also right that Ca₂O₂ looks wrong.  However, it's not that wrong.  The right answer is CaO.  This is because for ionic compounds (in general, compounds containing both metals and non-metals), you use the empirical formula.  In the empirical formula, you use the smallest ratio of elements.  So, instead of the 2:2 ratio in Ca₂O₂, you would write it as a 1:1 ratio in CaO.

b. The reaction of rubidium, Rb, with water is faster and more violent than the reaction of Na with water. Account for this difference in terms of the two metals' atomic structure and radius.

My work:

...I don't even know.

I would guess that it has something to do with the number of electrons in the outer shell of Rubidium in comparison to the number of elections in the outer shell of Sodium and their willingness to share with water. That's about as far as my brain got before I realized it had nothing to do with atomic structure and radius...

Well, the reactivity of the alkali metals comes from their willingness to give up electrons.  Which element will lose electrons more easily?

2. Gold is often used in jewelry. How does the relative activity of Au relate to its use in jewelry?

My work:

...What does relative activity have to do with anything? How easily it undergoes chemical reactions?

Uhm, going with the stupidest, almost sarcastic answer of them all, Gold is used in jewelry because not only is it shiny, it is practically unreactive, so people use it in jewelry because they would prefer not to have something hanging around their neck that would explode or burn their skin off or something of the like.

You have the right idea.  Gold is unreactive.  But, it's not exploding or burning that people are worried about.  Consider what would happen if people had iron jewelry.  Iron won't burn or explode, but it will still react slowly over time and form rust.  Gold is much higher on the activity series than many other common metals, so it is very resistant to corrosion.  Therefore, gold remains shiny for a long period of time and it won't rust away, so your investment won't disapear.

On a side note, gold is one of two metals whose color is not silver, which probably has something to do with its value.  The other metal is cesium which will explode or burn if you wear it as jewelry.

3. Explain how to use an activity series to predict certain types of chemical behaviour.

My work:

It seems like it would be so obvious, yet I can't help but think there's something I'm missing. The activity series tells how easily an element reacts in chemical reactions, so...using the activity series, you can figure out if chemical equations actually yield a product or not...?

That's pretty much as far as I got before I though that there was no way...

4. Aluminum is above copper in the activity series. Will aluminum metal react with copper(II)nitrate, Cu(NO₃)₂, to form aluminum nitrate, Al(NO₃)₃? If so, write the balanced equation for the reaction.

My work:

Al(s) + Cu(NO₃)₂ ----> Al(NO₃)₃ ?

This would be no, wouldn't it? Because the copper just...disappears? And if it disappears, it doesn't follow the law of conservation of mass, does it?

This is an example of a single replacement reaction.  Try reading about them in your textbook or at Wikipedia.  Here is my short summary of a single replacement reaction:

metal1 (elemental form) + metal2 (cation form) + anion -->  metal 2 (elemental form) + metal2 (cation form) + anion

For example, in the above reaction you have aluminum (cation form: Al³⁺, elemental form: Al) and copper(II) ions (cation form: Cu²⁺, elemental form: Cu).

Note that in single replacement reactions, you can consider hydrogen (cation form: H⁺, elemental form: H₂) a metal.

If it still doesn't make sense, then let us know so one of us can try to explain better.

1. SO₂ + H₂O ----> ?

My work:

Okay, so in my packet, it says it's supposed to be synthesis, which means that those two are supposed to come together to form one substance. But then, that means the H and the O and the S have to all make their way to the other side of the equation.

So...HSO...something?

SO₂ + H₂O ----> HSO₄

...I'm not sure which one would work, though. I vaguely remember that there existed an H₂SO₃ or...something. Which one are we supposed to pick? And then there's the issue with giving it a name. The product, I mean. (I'm trying to figure this out without a lot of help from my book, as to mimic what a test would be like so...) Hydrogen...sulfate, I would think it was.

Anyway, now, I would think I should balance.

2SO₂ + H₂O ----> 2HSO₄

...Would that be right? Now, here's a snag that I came up against. In addition to this, there was another equation which was like this: SO₃ + H₂O ----> ?

So...my question here would be, would it be the same answer? Would the balancing just be a little bit different? Or what?

Here I think you are overthinking the question a little.  Basically, the answer is that one molecule of water reacts with one molecule of sulfur dioxide to form ... (what would you get if you balance this equation).  For nomenclature, see http://en.wikipedia.org/wiki/Oxyanion

2. Hg₂CO₃ ----> Hg + HgO + ____

My work:

...Nothing. I have nothing. Honestly, with these kinds of equations I draw blanks. Complete and total blanks, if there was anything I needed help with, it would probably be problems such as these. I'm not sure if I fear it, or if it's just far too hard for me.

Well, try to figure out what atoms are missing from the reactant side.  Not all chemical reactions will have weird coefficients.  Just think of the product when the coefficients are one.

3. Zn + H₂SO₄ ----> ___ + ___

My work:

I'm just guessing. I know about...as much as I did in the above problem. I'm clueless, but as usual, I'm going to guess it.

Zn + H₂SO₄ ----> Zn(OH)₂ + S

...I don't know how I'm supposed to have gotten this. The one element on the right, I know, is supposed to replace one of the elements in the compound and push another out...so I just assumed.

I've never quite figured out the rule with OH, or things like that. When you balance it, I mean.

But still, I don't even think it's right. Not at all.

Again, this is a single replacement reaction.

Pb(NO₃)₂ + HI ----> ?

My work:

Pb(NO₃)₂ + HI ----> I(NO₃) + PbH₄

I have no clue how I got this. I know one is supposed to replace another depending on its place in the activity series, but...I don't know. There's no lead, no iodine, or anything. I think I'm confusing one thing with another. And then I know there are rules about how one of them, in a double replacement reaction, has to be at least a gas, water, or a precipitate.

[edit: listen to what Borek said.  My innitial explanation was wrong]


Anyway, chemistry is a tough subject to grasp because there are no real concrete rules that you can follow (like in physics).  Chemistry requires familiarity gained through a problem-solving approach.  By practicing and doing lots of practice problems, you will eventually develop a familiarity with chemical reactions and the rules of thumb that govern them.  So, you can't approach chemistry expecting to understand everything just by listening to your teacher and reading the book.  You must become familiar with the problem-solving process by doing as many practice problems as you can.  With enough practice and some helpful explanations from teachers, peers, and chemical forums members, I'm sure that these concepts will eventually "click" with you.

[Borek]

Pb(NO₃)₂ + HI ----> ?

My work:

Pb(NO₃)₂ + HI ----> I(NO₃) + PbH₄

I have no clue how I got this. I know one is supposed to replace another depending on its place in the activity series, but...I don't know. There's no lead, no iodine, or anything. I think I'm confusing one thing with another. And then I know there are rules about how one of them, in a double replacement reaction, has to be at least a gas, water, or a precipitate.

This is a single replacement reaction and lead is in the activity series (at least on wikipedia).

I would concentrate on PbI₂ solubility...

[xiankai]

2. Hg2CO3 ----> Hg + HgO + ____

2 Hg atoms, 1 C atom, 3 O atoms on the left side,

2 Hg atoms, 1 O atom on the right side,

what's missing?

[constant thinker]

Yggdrasil did a good job, but I'll add in what helped me.

When I first really started getting into chemistry, how things reacted used to always screw me up.

One tip I have for you though is always look at what you have for polyatomic ions. That can help you identify what stays the same, but it doesn't work in every situation.

Unbalanced example of what I mean about polyatomic ions...
H₂SO₄ + NaOH --> Na₂SO₄ + H₂O
The ions you wind up with on the reactant side are...
2H⁺  SO₄^-2 + Na⁺ OH^-
Now look at the products.

What do you see? The H⁺ wound up with the OH^-, and 2 Na⁺ wound up with the SO₄^-2.

That's how I started figuring things out. I started treating polyatomic ions as one whole thing.

When you look at your Zn + H₂SO₄ reaction it won't be like the example with H₂SO₄.

Just take it step by step when it comes to reactions. Forget about names, and all of that stuff. Just try to identify what type of reaction it is, and what has what for a charge.

One comment though I have to make about the Pb(NO₃)₂ + HI reaction (Borek's post is an excellent tip) is look at the charges on I and NO₃.

[Edit] I was debating on states of matter, but I'm afraid that it may be a bit confusing. It also may help though, but I just decided not to include them.

[english]

+1 Yggdrasil!

 

[Kimyko]

Yes, thank you so much, everybody that helped me. ...I think I understand it just a little bit more. A few parts remain a bit sketchy, but I think I know enough now that if I picked at it a bit longer, I can come to my own conclusion. ...Unless the conlcusion is wrong, but nevermind that.

Actually...I do have one more question. (I'm sorry, I guess I'm just slow..)

Uhm, what constant thinker said got me thinking, and reminded me of Ionic Equations, which, I also failed to figure out.

Just for clarification, the charge...valence, or something, is the number hovering on the top of the element's name, right? And that's what the ion...is?

Is that right?

Uhm, anyway, as for that, I was confused about the steps you go through to do a Net Ionic Equation.

One of the ones in our packet was: KC₂H₃O₂ + H₂SO₄ ---->

So...mostly, I trip on the first step. I vaguely understand what to do afterwards, but it's starting that's really the difficult part for me. Actually, the first part is to complete and balance, that...might not be too hard. It's writing the total ionic equation that gets me.

But the balanced/completed equation (at least what I got), was:

KC₂H₃O₂ + H₂SO₄ ----> 3H₂O + 2NaSO₄

My problem - assuming that I got the above equation right - is mostly pulling that apart into ions, getting rid of the spectator ions...and completing the equation. If it's not too much trouble, could I please get some help with that?

Uhm, though, I remember vaguely that my teacher said something about...always having water as one of the results, and everything else goes away. (Chances are, though, I wrote it wrong in my notes) ...Could someone also tell me if that's wrong or right? It might be something to do with Neutralization Reactions...or something? (There are so many, I can't seem to get them straight)

Anyway, I would be (again) really greatful for help, though, I'm already very thankful for all those who helped me before. It cleared up some of the problems I had. Enough, at least, to get me going.

I hope it's okay that I asked another question. I thought it would be redundant to create another thread solely for the purpose of that. (I'm sorry if that's what I was supposed to do, though)

[DrCMS]

I've been reading this thread from the start and people have been trying to help you but you seem not to be taking it in so i decided to post my reply.  These equations are very simply and you are making a complete mess of them.

Your latest one is a prime example:

KC₂H₃O₂ + H₂SO₄ ----> 3H₂O + 2NaSO₄

You have a potassium salt on one side and a sodium salt on the other.  That is not possible.
If there is potassium in the reactants there must be potassium in the products. 
There is no sodium in the reactant so there must be no sodium in the products.

You have an organic material in the reactants but no carbon in you products.  That is not possible.

Both sides of the equation must have the same elements.

In this case you have the salt of a weak acid / strong base reacting with a strong acid to give
the salt of a strong acid / strong base and a weak acid.

The reaction is:

Potassium acetate + Sulphuric acid  -->  Potassium Sulphate + acetic acid.

Potassium has a charge of +1 (written as K⁺¹ or just K⁺  ) and Sulphate is -2 ( written as SO₄^-2) so you need two Potassium's to give the neutral salt Potassium Sulphate which is therefore written as K₂S0₄.

That gives a balanced:

2KC₂H₃O₂ + H₂SO₄ ----> K₂SO₄ + 2C₂H₃O₂H

All the other equations you were asking about can be solved in the same way. 

Look at the reactants,
make sure you have the same elements on both sides,
balance the charges and
then finally balance the full equation.

[billnotgatez]

I look at this post and the answers. No one mentions the Periodic Table and how to use it. Is the Periodic Table now considered old school? Can you assume when you answer these questions that the original poster understands the Periodic Table? Did the original poster imply that they understood the concepts behind the Periodic Table? When answering questions on an exam is the student allowed to have a Periodic Table to assist them or do they have to memorize.

http://en.wikipedia.org/wiki/Periodic_Table

[Kimyko]

Actually, DrCMS, I just looked at the one I put up, and you're right, it doesn't make sense. It was a typo that I didn't notice for some reason when I sent it. I balanced all of the problems on the page before typing up my question, and accidentally wrote the wrong formula in for the answer. I'm sorry.

The actual (balanced) equation was: 2H₂SO₄ + 2 NaOH ----> 3H₂O + 2NaSO₄

At least those have all of the elements, I suppose.

And from what you said, this is what I should do next, right? (Assuming the above is correct)

2H₂⁺ + 2SO₄^-2 + 2Na⁺ + 2OH^- ----> 3H₂O + 2Na⁺ + 2SO₄^-2

Then, you get rid of spectator ions, because I'm almost one hundred percent sure spectator ions make an appearance somewhere.

2H₂⁺ + 2OH^- ----> 2H₂O

So finally, that's what I would have gotten. Is this right, or have I made another mistake?

Also, I apologize, I know these are very simple and it must be pretty annoying to most people that I'm asking such redundant questions, but that's really why I decided to come here to ask for help instead of continually bugging my teacher with these. I'm sorry if I'm wasting your time or anything...

Uhm, and, billnotgatez, I am allowed to use the Periodic Table on my tests and I'm familiar on very simple things about the Periodic Table such as some basic rules to finding out the charge and stuff like that.

Anyway, thanks for all the help.

[Borek]

2H₂⁺

2H⁺

When sulfuric acid (or any other acid) dissociates it gives H⁺ cations. 2 in the case of sulfuric acid, 1 in the case of muriatic (hydrochloric) acid and so on.

2H₂⁺ is four atoms, not two.

H₂⁺ is a molecule made of two atoms with single posititve charge. It can exist only in gaseous state - and is rather exotic for HS level chemistry.

[DrCMS]

I'm not having a go at you Kimyko but you need to look at what you are doing and writing down.

You've put the following down as a balanced equation:

2H₂SO₄ + 2 NaOH ----> 3H₂O + 2NaSO₄

but it is not correct.  You have to balance the charges.

In my last post I showed you Potassium Sulphate is K₂S0₄. 
If you look on you periodic table Sodium is just above Potassium in Group I and they react in a similar way so Sodium Sulphate is Na₂S0₄


The balanced equation for the full reaction is then:

H₂SO₄ + 2NaOH ----> 2H₂O + Na₂SO₄

You might also put:

H₂SO₄ + NaOH ---->  NaHSO₄ + H₂O

NaHSO₄ + NaOH ----> H₂O + Na₂SO₄

These things are easy and I'm sure you can do them but you have to look at what you're writing down.

You can not put 1 + 2 ---> cat because it does not make any sense. 

In the same way you can not have elements/ions or charges appearing or disappearing from either side of these chemical equations.  You have to make each side balance and only include real chemicals.

[english]

No student should ever have to memorize the periodic table, billnotgatez.

[Kimyko]

I thought that Hydrogen was a diatomic molecule (is that even the right word?), like Oxygen. So I thought that those kinds of atoms always had a sub...number thing of 2 when they are alone in an equation or something like that.

...How off am I, exactly?

And I know you're not having a go at me, DrCMS, and I really appreciate you helping me out. I also know that I have to focus more, I guess, on the problem in front of me and avoid making those....really ignorant mistakes. Is there even a way to do that? I honestly don't know why I space out like that while doing anything, not even chemistry. 

But my only mistake in that other equation was that I got the forumula wrong for Na₂SO₄, right?

[Borek]

No student should ever have to memorize the periodic table, billnotgatez.

I tend to disagree. Perhaps that's not the best way of learning chemistry, but you can't cope with it if you don't remember lot's of things. How do you expect to know that cesium sulfate is Cs₂SO₄ without either remembering that Cs is alkali metal (thus +1) or it is +1 (which gives the same formula of sulfate, but doesn't help to suppose it will be rather weakly complexed, will have most of salts soluble, will have almost entirely ionic salts and so on).

In case you want to say "You can always check these things" my answer is - "you don't want to waste your life checking alkali metals valence, you better remember it right now"