Chemistry and balancing equations help

[starr9]

Ok so I know some of you amazing ppl on here understand Chemistry and I need some help please!!! I have never done any chemistry in my life (not even high school as I thought Id never need it :?) so I have a very limited understanding of it.

At the moment we are balancing equations and I thought I got it but it turns out I dont!! We have to put down our working out as well when we answer the question. So can anyone help me understand how to do it or point me in the direction of a good site that explains it in a super simple way!!???

Iv had a look at the Khan academy but I need another good site just so I can be sure Im getting it!!!

Thank you in advance to anyone who can help!!!

 

[CrystalMoon]

Good luck Starr, I am mathmatically challenged so all I can do is wish you well

 

[Robo1]

If you have a specific problem I can help, but I'm not familiar with any specific sites. A quick google search turned up this site, which seems to fit your description.

 

[starr9]

If you have a specific problem I can help, but I'm not familiar with any specific sites. A quick google search turned up this site, which seems to fit your description.

Thanks! I will see how I go. Ill find the problem I got given and put it up if you/anyone could help me work it out that would be amazing!!!

MgCl2 + Al(NO3)3 --> Mg(NO3)2 + AlCl3

I need to have all the working out in steps as well. Im going to have a try tomorrow at it as my head is going to explode atmo with trying to understand my teacher and her crazy rambles.......

 

[Wrightpython]

does this help or hinder
magnesium nitrate, Mg(NO3)2, would dissociate to form one Mg2+ ion for every two NO3 .... and 3 mol of Cl– per mole of AlCl3 dissolved. Moles Al3+ = (. ) 3. 3. 3. 3. 0.45 mol AlCl. 10 L. 1 mol Al .... 4.19 a) MgCl2(s) → Mg2+(aq) + 2 Cl–(aq) ...

 

[Robo1]

Not sure how this will go with formatting. But here goes...

MgCl[SUB]2[/SUB] + Al(NO[SUB]3[/SUB])[SUB]3[/SUB] --> Mg(NO[SUB]3[/SUB])[SUB]2[/SUB] + AlCl[SUB]3[/SUB]

align="left" width="250" style="width: 250px"
|-
| Atom
| Left side
| Right side
| Status
|-
| Mg
| 1
| 1
| ✓
|-
| Cl
| 2
| 3
| x
|-
| Al
| 1
| 1
| ✓
|-
| NO[SUB]3[/SUB]
| 3
| 2
| x
|-

NB: You can consider the 3 NO[SUB]3[/SUB] as 3 N and 9 O, but in this example NO[SUB]3[/SUB] doesn't dissociate so you can keep it simple and consider it as a single component.

Pick an atom that is in one starting reagent (left side) and one product (right side). They all fit the bill here, so lets pick Cl
It's usually best to keep to whole integers, so to balance the number of Cl atoms you put
3MgCl[SUB]2[/SUB] + Al(NO[SUB]3[/SUB])[SUB]3[/SUB] --> Mg(NO[SUB]3[/SUB])[SUB]2[/SUB] + 2AlCl[SUB]3[/SUB]

You now have:

align="left" width="250" style="width: 250px"
|-
| Atom
| Left side
| Right side
| Status
|-
| Mg
| 3
| 1
| x
|-
| Cl
| 6
| 6
| ✓
|-
| Al
| 1
| 2
| x
|-
| NO[SUB]3[/SUB]
| 3
| 2
| x
|-

So it looks like things got worse, but bear with me. Now without affecting the number of Cl atoms, balance another atom which only has one starting reagent and product (if possible), say Mg.
3MgCl[SUB]2[/SUB] + Al(NO[SUB]3[/SUB])[SUB]3[/SUB] --> 3Mg(NO[SUB]3[/SUB])[SUB]2[/SUB] + 2AlCl[SUB]3[/SUB]

You now have:

align="left" width="250" style="width: 250px"
|-
| Atom
| Left side
| Right side
| Status
|-
| Mg
| 3
| 3
| ✓
|-
| Cl
| 6
| 6
| ✓
|-
| Al
| 1
| 2
| x
|-
| NO[SUB]3[/SUB]
| 3
| 6
| x
|-

Now pick one of the remaining two, say Al. Without changing the number of Cl or Mg, balance Al.
3MgCl[SUB]2[/SUB] + 2Al(NO[SUB]3[/SUB])[SUB]3[/SUB] --> 3Mg(NO[SUB]3[/SUB])[SUB]2[/SUB] + 2AlCl[SUB]3[/SUB]

You now have:

align="left" width="250" style="width: 250px"
|-
| Atom
| Left side
| Right side
| Status
|-
| Mg
| 3
| 3
| ✓
|-
| Cl
| 6
| 6
| ✓
|-
| Al
| 2
| 2
| ✓
|-
| NO[SUB]3[/SUB]
| 6
| 6
| ✓
|-

Congratulations, it's now balanced. You can try doing this be doing things is a different order, say Mg or Al first.

 

[Bluetongue1]

There is a technique I can show you that will allow you to successfully balance any equation that does actually occur, no matter how complex it may look at first. With a little bit of practice and care, these problems become routine.

There are a few equations that seem to present difficulties but by following a couple of added rules, they are readily solved.

This is one one of the middle difficultly equations. It actually took me almost one minute to do. Bear in mind that I have plenty of practice in the technique mentioned.

The solution is...

3 MgCl2 + 2 Al(NO3)3 --> 3 Mg(NO3)2 + 2 AlCl3

Blue

Sorry Robo, you posted while I was typing.

 

[Beard]

Now, I'm amazing, of this I have no doubt, just ask and i'll tell you but this is a little outta my field of expertise

It (this specific subject) ended in year 12 for me, 15 years ago.

 

[Renenet]

Oh hell, I'm going to have to do this soon...

Good luck, Starr!

 

[Bluetongue1]

I attempted to paste a worked example to show the different setting out I utilise but lost all formatting in the process.