Chemistry Whizzes Help w/ Limiting Reactions

Off Topic
1

So I have this problem I cannot solve, and it is stressing me out because I know a similar problem will be on an exam tomorrow.

It reads “How many grams of ammonia are evolved when 34 grams of ammonium chloride are added to 140 grams of barium hydroxide?”

I tried to balance it but I am having trouble and it just doesn’t look/feel right…I got

NH4CL + Ba(OH)2 → NH4 + BaCl2 + O2

I haven’t even tried balancing it because I’m not sure where to go next…

Do I use stoichiometry (have to) to find out the limiting agent by going from ammonium chloride to ammonia, and then from barium hydroxide to ammonia?

Thanks for any help.

2

god i hate stoichiometry, yeah you’re probably going to have to find the limiting agent. that’s all i know though.

3

Hmmm… I think you left out a water, but I’m not sure. If you don’t understand this, you’re kind of screwed at this point. Work though problems you have the answers to.

4

This is only one of the problems on the exam, I know everything else. I can balance problems just fine, and I can do combustion reactions, and mole to mole conversions and such.

I just can’t figure out this limiting shit and its bugging me.

5

You have your equation wrong. It says it makes ammonia not ammonium. Should be

2NH4Cl + Ba(OH)2 → 2NH3 + BaCl2 + 2H20

Mols Barium Hydroxide: 140g/MM = 0.81 mols
Mols Ammonium Chloride: 34g/MM = 0.63 Mols

Since you get 2 mols ammonia for every 2 mols Ammonium Chloride you have a 1:1 ratio. So you just have to figure out how much 0.63 mols of ammonia weighs.

Ans: about 10.71 g ammonia

6

Just balance it( I think you forgot a H2 or else the reaction isn’t possible, shit-reaction), convert grams to moles

then the tricky part begins
eg; 2NH4Cl + Ba(OH)2–>2NH4 + BaCl2 + O2 + H2
…2 moles…3 moles…,…
ONE Ba can react with TWO Cl’s
to form BaCl2 right?
You only got 2 moles Cl2 and 3 moles Ba
so not all the Ba’s can react
There is you limiting agent : NH4Cl

for the rest I’m not going to help you because I don’t think it is worth converting grams into moles and explaning it entirely to a guy I don’t know and will never meet in my life but I do think that you have to post a picture of your girlfriend because we tried to help you.

good luck
Erasmus

good luck

7

[quote]Unaware wrote:
You have your equation wrong. It says it makes ammonia not ammonium. [/quote]

I knew there was a reason I couldn’t intuitively balance it out. Thanks.

8

[quote]Unaware wrote:
You have your equation wrong. It says it makes ammonia not ammonium. Should be

2NH4Cl + Ba(OH)2 → 2NH3 + BaCl + 2H20

Mols Barium Hydroxide: 140g/MM = 0.81 mols
Mols Ammonium Chloride: 34g/MM = 0.63 Mols

Since you get 2 mols ammonia for every 2 mols Ammonium Chloride you have a 1:1 ratio. So you just have to figure out how much 0.63 mols of ammonia weighs.

Ans: about 10.71 g ammonia[/quote]

that’s even a better explanation

9

[quote]Mutu wrote:
So I have this problem I cannot solve, and it is stressing me out because I know a similar problem will be on an exam tomorrow.

It reads “How many grams of ammonia are evolved when 34 grams of ammonium chloride are added to 140 grams of barium hydroxide?”

I tried to balance it but I am having trouble and it just doesn’t look/feel right…I got

NH4CL + Ba(OH)2 → NH4 + BaCl2 + O2

I haven’t even tried balancing it because I’m not sure where to go next…

Do I use stoichiometry (have to) to find out the limiting agent by going from ammonium chloride to ammonia, and then from barium hydroxide to ammonia?

Thanks for any help.[/quote]

First of all, that equation is written wrong. There is an ammonium ion on the right side of the equation where there should be ammonia.

Also, water is missing.

Try writing the equation correctly, then balancing, to see if it becomes clearer to you.

10

Well goddamnit this isn’t fair now it just looks like I showed up late to the party and wanted to participate.

Damn slow-ass internet forums!

11

[quote]NewDamage wrote:
Well goddamnit this isn’t fair now it just looks like I showed up late to the party and wanted to participate.

Damn slow-ass internet forums![/quote]

So, you not only pull (almost) 700 lbs, but you know your chemistry as well?

Dude, who do you think you are? :slight_smile:

12

Thanks a lot guys, you just saved me like 1/6th of the points on the exam.

In our class we use this little chart that shows all the poly-atomic ions like ammonIUM, but it excludes ammonIA, and I had no idea how to express it. I incorrectly figured it was just ammonium…

Chemistry - 1 Me- 0 >: (

13

[quote]PonceDeLeon wrote:

So, you not only pull (almost) 700 lbs, but you know your chemistry as well?

Dude, who do you think you are? :)[/quote]

Muahahahaha

To the original poster : once you get the equation written write, ALWAYS BALANCE THE EQUATION.

ALWAYS.

ALWAYS ALWAYS ALWAYS.

That should be your first step.

Did I mention ALWAYS?

Sorry, it was just drilled into my brains years ago…

BALANCE! BALANCE!

14

[quote]PonceDeLeon wrote:
NewDamage wrote:
Well goddamnit this isn’t fair now it just looks like I showed up late to the party and wanted to participate.

Damn slow-ass internet forums!

So, you not only pull (almost) 700 lbs, but you know your chemistry as well?

Dude, who do you think you are? :)[/quote]

So much for the “big muscle, small brain” notion

15

[quote]Unaware wrote:
You have your equation wrong. It says it makes ammonia not ammonium. Should be

2NH4Cl + Ba(OH)2 → 2NH3 + BaCl2 + 2H20

Mols Barium Hydroxide: 140g/MM = 0.81 mols
Mols Ammonium Chloride: 34g/MM = 0.63 Mols

Since you get 2 mols ammonia for every 2 mols Ammonium Chloride you have a 1:1 ratio. So you just have to figure out how much 0.63 mols of ammonia weighs.

Ans: about 10.71 g ammonia[/quote]

THis is the correct answer.
(sorry I’m late!)