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 1 
 on: Today at 06:55:45 PM 
Started by amiv4 - Last post by amiv4
so would it be 24.8% Cl-

 2 
 on: Today at 05:40:55 PM 
Started by Zell - Last post by Zell
Hey everyone! I'm having trouble with the following question:

Tell whether it is possible to make a 1.0 M solution at 0 degrees C?
a) CuSO4 x 5H2O, solubility = 23.1g/100mL
b) AgNO3, solubility 122g/100mL

I don't know how to begin or work through this problem. Thanks in advance! Grin

 3 
 on: Today at 05:34:16 PM 
Started by Chemistry Tutor - Last post by Zell
I searched for "chemistry help" on Google.

 4 
 on: Today at 03:51:50 PM 
Started by roseybabyy - Last post by roseybabyy
This question is from the synthesis of alum lab.

"Why should you not wash the crystals with pure water?"

Thanks!

 5 
 on: Today at 03:24:08 PM 
Started by tesfaw - Last post by tesfaw
Do copper and a hydrogen ion create a reaction?

 6 
 on: Today at 01:53:14 PM 
Started by SchoolBoyDJ - Last post by SchoolBoyDJ
Second organic test this cominig monday Tongue

1. Which of the following is not an electrophile?
a) AlCl4-[/sub]   b) BH3     c)  NH4+

I was able to eliminate c, but the other two gave me trouble.  My thinking was that:  If carbon can form 4 bonds (sp3 hybridized), why can't Boron?  So I was thinking Boron had an open p orbital (currently sp2 hybridized).  AlCl4- seemed to already be full.  I know that elements in period 3 or higher can form more than the expected number of bonds, but why the heck would something with full orbitals, and a negative charge still want more negative/electrons  Huh

2.  The following is a ______ alkene



a)monosubstituted
b)disubstituted
c)trisubstituted
d)tertasubstituted


Now you'd name this 2-ethyl-1-butene right?  I thought this would be monosubstituted because it has one group coming off the main chain.  I guess substitution takes into account all R groups (everything but H right?) coming off the double bond?

3.  When 2-pentene is heated with a catalytic amount of I2, an equilibrium concentration of two isomers is obtained.  The dominant isomer is:

c) an equal amount of each is present at equilibrium



I didn't have much of a guess on this, and I guess that's because I don't know what is happening to the molecule while reacting with I2. A is the correct answer, but with the knowledge I have now I'd argue b as it seems like it would be more stable...the pi bond almost seems more enclosed.  Help >_<

Thanks everyone!


 7 
 on: Today at 11:31:22 AM 
Started by harley08 - Last post by harley08
Thank you, but believe it or not there was about 2 sentences and then it cuts off like a misprint. Unfortunately our teacher doesn't use the book to instruct from, she uses overhead projection and speeds thru those like a tornado, which can be frustrating. It is more of a teach yourself class. Anyway, THANK YOU, for both the help and letting me vent there.

 8 
 on: Today at 08:24:20 AM 
Started by harley08 - Last post by Otis
In one mole of your compound you have 1 mole of Al3+ and 3 moles of Br-, that's what the subscripts mean. Now use your PT (Periodic Table of the Elements) to find the mass of one mole of the element.

For Al3+, 26.98 grams Al3+/1 mole Al3+ times 1 mole of Al3+ equals 26.98 grams Al3+

For Br-,  79.90 grams Br-/1 mole Br- times 3 moles Br- equals 239.70 grams Br-

This should have been explained in you chem book with several examples.

Otis

 9 
 on: Today at 08:15:24 AM 
Started by harley08 - Last post by harley08
I have a question I am completely stumped on, we did not go over this in class and I can't find any type of problem like in in our books and I am the type that has to see how and why I am getting there in anything.
The question is; Calculate the mass in grams of positive and negative ions contained in one mol of AlBr3?
Any help would be so much appreciated, as well as any sites that I could go to to help with chemistry in general, but of course the above question is pressing right now as I am stressed as to how to do it.

 10 
 on: Today at 08:05:03 AM 
Started by cyborg22 - Last post by Otis
Assign oxidation number following the rules in your chem book. Most important but often neglected - use the rules in the order given. Do not play hop-scotch with the rules.

  1. All atoms in their elemental state are assigned zero
  2. Group 1 and 2 and other simple ions are assigned their normal charge
  3. Hydrogen is assigned 1+, except hydride is assigned 1-
  4. Oxygen is assigned 2-, except peroxide is assigned 1-
  5. The sum of the oxidation numbers must equal the net charge on the polyatomic ion or  compound.

Good luck,

Otis

Added

To balance the redox equation see my reply (#9) at http://www.mychemistrytutor.com/forums/ap-chemistry/balancing-oxidation-reduction-equations/
     

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