Chemistry 12 Help
<div class="IPBDescription">I exceeded the Ksp, blood soldifying...</div> Provincials exams are coming up, I need 90% minimum to get $3500 scholarship. I want money.
I need help:
<i>Concerning Solubility Equilibrium</i>:
Starting off with what I understand...
<i>The ion concentrations in 2.00L of 0.32M K3PO4 are: {[K+]; [PO43-]}
a) 0.16M; 0.16M
b) 0.32M; 0.32M
c) 0.96M; 0.32M
d) 0.48M; 0.16M</i>
This is easy enough. K3PO4 dissociates into 3(K) and 1(PO4). Since the molarity of the solution is already given within the 2.00L volume, we can safely assume the 2.00L was added to try to throw people off. Thus, the correct answer is:
<b>c) 0.96M; 0.32M</b>
Now, something I don't understand...
<i>Which of the following solutions would have [Fe3+]=0.020M?
a) 0.80 L of 0.020 M Fe2(NO3)3
b) 0.50 L of 0.040 M Fe2(C2O4)4
c) 0.40 L of 0.050 M Fe(NO3)3
d) 0.50 L of 0.040 M FeC6H5O7</i>
I'm not exactly sure what makes this question different from the first one, but I tried using the same principles, and nothing works. Every compound, when dissociated, will yield a concentration higher than 0.02M of Fe3+.
a) 0.020 x2 Fe = 0.040
b) 0.040 x2 Fe = 0.080
c) 0.050 x1 Fe = 0.050
d) 0.040 x1 Fe = 0.040
My next guess is that perhaps volume played a role in <b>this</b> question, but I don't exactly see why it does in this case...
The answer?
<b>b) 0.50 L of 0.040 M Fe2(C2O4)4</b>
Why?
[edit]I am open to the possibilty that all four answers are messed up, but I would like an explanation as to why.[/edit]
I need help:
<i>Concerning Solubility Equilibrium</i>:
Starting off with what I understand...
<i>The ion concentrations in 2.00L of 0.32M K3PO4 are: {[K+]; [PO43-]}
a) 0.16M; 0.16M
b) 0.32M; 0.32M
c) 0.96M; 0.32M
d) 0.48M; 0.16M</i>
This is easy enough. K3PO4 dissociates into 3(K) and 1(PO4). Since the molarity of the solution is already given within the 2.00L volume, we can safely assume the 2.00L was added to try to throw people off. Thus, the correct answer is:
<b>c) 0.96M; 0.32M</b>
Now, something I don't understand...
<i>Which of the following solutions would have [Fe3+]=0.020M?
a) 0.80 L of 0.020 M Fe2(NO3)3
b) 0.50 L of 0.040 M Fe2(C2O4)4
c) 0.40 L of 0.050 M Fe(NO3)3
d) 0.50 L of 0.040 M FeC6H5O7</i>
I'm not exactly sure what makes this question different from the first one, but I tried using the same principles, and nothing works. Every compound, when dissociated, will yield a concentration higher than 0.02M of Fe3+.
a) 0.020 x2 Fe = 0.040
b) 0.040 x2 Fe = 0.080
c) 0.050 x1 Fe = 0.050
d) 0.040 x1 Fe = 0.040
My next guess is that perhaps volume played a role in <b>this</b> question, but I don't exactly see why it does in this case...
The answer?
<b>b) 0.50 L of 0.040 M Fe2(C2O4)4</b>
Why?
[edit]I am open to the possibilty that all four answers are messed up, but I would like an explanation as to why.[/edit]
Comments
so you have .040 Molarity = (number of moles)/.5 Liters
now do basic algebra .040 molarity times .5 liters = number of moles
so number of moles = .020
i think this would help me to show if im right if you mean the capital M if so i would look into it more. If lower case m then that stands for moles not molarity so you found your .020 moles.
so you have .040 Molarity = (number of moles)/.5 Liters
now do basic algebra .040 molarity times .5 liters = number of moles
so number of moles = .020
i think this would help me to show if im right if you mean the capital M if so i would look into it more. If lower case m then that stands for moles not molarity so you found your .020 moles.<!--QuoteEnd--></td></tr></table><div class='postcolor'><!--QuoteEEnd-->
It's asking for the 0.020 <b>molarity</b> of Fe3+, not the number of moles of Fe3+.
I still don't underatand why you need to multiply the molarity with the volume in this question, while the previous question didn't require the multiplication of molarity with volume.
What makes it more annoying is that the molecule is Fe<b><u>2</u></b>(C2O4)4. which means that when it dissociates, it <u>doubles</u> the concentration of Fe3+, compared to that of the [Fe2(C204)4].
so you have .040 Molarity = (number of moles)/.5 Liters
now do basic algebra .040 molarity times .5 liters = number of moles
so number of moles = .020
i think this would help me to show if im right if you mean the capital M if so i would look into it more. If lower case m then that stands for moles not molarity so you found your .020 moles.<!--QuoteEnd--></td></tr></table><div class='postcolor'><!--QuoteEEnd-->
It's asking for the 0.020 <b>molarity</b> of Fe3+, not the number of moles of Fe3+.
I still don't underatand why you need to multiply the molarity with the volume in this question, while the previous question didn't require the multiplication of molarity with volume.
What makes it more annoying is that the molecule is Fe<b><u>2</u></b>(C2O4)4. which means that when it dissociates, it <u>doubles</u> the concentration of Fe3+, compared to that of the [Fe2(C204)4]. <!--QuoteEnd--></td></tr></table><div class='postcolor'><!--QuoteEEnd-->
<span style='color:white'>that's exactly right, it has no answer unless it's a typo and acctually asking for moles.</span>
[edit]sorry about the double post, quoting properly in an edit is really hard
[edit again] made text in original post white just for the hell of it
And why?
On a little out of the way education website I found the following question
38. Which of the following would have the [Fe3+] = 0.020 M?
A. 0.40 L of 0.050 M Fe(NO3)3
B. 0.80 L of 0.020 M Fe2(SO4)3
C. 0.50 L of 0.040 M FeC6H5O7
D. 0.50 L of 0.010 M Fe2(C2O4)3
And the answer.... was D.
Its a typo. Has to be. And whoever gave you that document is very, VERY lazy.
I had it copy and pasted from an online quiz site; that POC was giving me a hell of a time.
And once again, volume is ignored. By golly, I think I might understand it...
Fe2(C2O4)4
As far as I know, iron can exist as a 2+ ion and as a 3+ ion. Since the oxalate ion (C2O4) is 2-, this formula implies that iron is 4+ here. Which does not exist. Even if it did exist, it means that this would yield no Fe3+ ions in the solution because they would all be 4+.
The question is bull, and it is all as simple as you think it is. I wish I could get money for answering questions like those. <!--emo&???--><img src='http://www.unknownworlds.com/forums/html//emoticons/confused.gif' border='0' style='vertical-align:middle' alt='confused.gif' /><!--endemo-->
Just curious, what level of schooling is this? Age? Country?
Furthermore, you can get more than that. They;'re just not as stable or as well known.
IIRC its Fe 3+ purely because thats the natural oxidative state of iron... well, that or Fe 2+. While it'll be 4+ when forming the oxalate it'll quickly form the more stable Fe 3+ when separated... but thats all tangential to the question, hehe.
Urg I hate chemistry... for some reason I devoted 9 years of my life to it. Kill me.
Chemistry grade 12, (age 18, without repeats), British Columbia, Canada.
I need a 90% average on my four courses of Bio, History, Chem, and English, which means very little room for failure for my scholarship.
If you're masochist, or just want to see how inadequate our education is, <a href='http://s95094929.onlinehome.us/Provincials/' target='_blank'>take a stab at some exams</a>! ("k" indicates answer key).
If you look at the exams, you might find the older they are, the tougher they get.
Easier exams = Better statistics
w00t!
[Telepathic]So you would be writing thursday afternoon then?[/Telepathic]
BTW, where in BC do you live?
[Telepathic]So you would be writing thursday afternoon then?[/Telepathic]
BTW, where in BC do you live? <!--QuoteEnd--> </td></tr></table><div class='postcolor'> <!--QuoteEEnd-->
Heh... nice try you Cleo wannabe....
<span style='font-size:21pt;line-height:100%'>HOLY CRAP, YOU'RE RIGHT!</span>
/study overdrive initiated...
Your average Vancouverite here.