Chemistry - March 2007

if covalent can you briefly expain

2007-03-04 18:18:07 · 3 answers · asked by Anonymous

if covalent can you briefly explain

2007-03-04 18:17:10 · 3 answers · asked by Anonymous

a) SeF2


b) XeF4O


c) XeO4


d) ClO3-


e) BrF3

2007-03-04 18:09:15 · 1 answers · asked by mimi 1

I'm doing a lab on it and honestly, whats the difference if i add hydro / sulfuric acid? regarding pH levels and everything. I missed the first part of the lab b/c I was sick and I come back and i have to do a write up >< help !

2007-03-04 18:02:07 · 3 answers · asked by wasabi 1

2007-03-04 17:44:28 · 8 answers · asked by tamar a 1

After putting starch in the solution for 10 mins, where it should normally change into a deep-blue colour with thiiodide, it does not. Why might it not change colour? Thanks for your explanation.

I was thinking of maybe there was enough of the reactants, and so there is no colour change, but then there should be at least some colour change (maybe to a faint blue). I'm not sure anymore.

2007-03-04 17:18:15 · 1 answers · asked by syndrome1765 1

What are some possible reasons as to why Mendeleev couldn't predict the existence of the noble gases?

2007-03-04 17:15:01 · 2 answers · asked by Anonymous

Or is willing to research potential medicines? Any help would be greatly appreciated.

2007-03-04 17:12:53 · 2 answers · asked by Elias 5

can u plz show with examples how the electronic configuration of an element changes when its in the 1st excited state,2nd excited state...?

2007-03-04 17:10:01 · 2 answers · asked by Knightmare 1

I need help on Ideal Gas Law.
At what temperature will 6.13 g of oxygen gas exert a pressure of 3.00 atm in a 10.0 L container?
_______K
Please explain how to do this problem
thanks in advance

2007-03-04 16:52:43 · 6 answers · asked by Legend 4

hi pls help me for explovise metahls.
tank you so much.
all thing about firework and explovies, fuse, hand bomb,.................

2007-03-04 16:48:10 · 7 answers · asked by Anonymous

can anyone explan it 4 me

2007-03-04 16:44:20 · 3 answers · asked by Nini 1

2007-03-04 16:41:47 · 2 answers · asked by Anonymous

2007-03-04 16:40:30 · 1 answers · asked by Anonymous

2007-03-04 16:36:15 · 1 answers · asked by emiro higure 1

I have the answer for this question from manual but I do now understand on how to get to the solution. Can someone explain ti to me? Thanks.

Q: A mixture weighing 6.2 grams is 28% silicon dioxide or sand, 36% sodium chloride or table salt, and the rest being sodium bicarbonate or baking soda. How many grams of baking soda are present in the sample?

A: 2.852g

2007-03-04 16:10:58 · 5 answers · asked by Anonymous

2007-03-04 16:05:20 · 3 answers · asked by Anonymous

Hi, I have a question.

Is it possible to "PHYSICALLY" separate something like table salt, NaCl, sucrose, or soium chloride? Why or Why not...

2007-03-04 16:01:38 · 2 answers · asked by Anonymous

2007-03-04 16:00:14 · 2 answers · asked by DrRocafella 2

2007-03-04 15:53:13 · 3 answers · asked by loktao s 2

The reaction of 50 mL of Cl2 gas with 50mL of CH4 gas via the equation: Cl2 (g) + CH4 (g) -------> HCL (g) +CH3Cl (g) will produce a total of ____ mL of product. pressure and temp are constant.

If you could tell me HOW to do it, that would be great. thanks!

2007-03-04 15:50:05 · 2 answers · asked by bree 3

What is the minium kelvin temperature the system must be heated to to make the below reaction product favored ?



C (graphite) + CO2 (g) → CO (g)


What is the change in entropy (J/K-mol) for the universe of the above reaction at 25 oC ?

For the same reaction, what is the maximum useful work (kJ) that can be performed on the surroundings from the production of 4.3 moles of CO (g) ?

2007-03-04 15:49:53 · 1 answers · asked by Anonymous

A. the heart B. muscle fibers C. neurotransmitterers D. bones

2007-03-04 15:43:59 · 1 answers · asked by ken 1

It is a chemistry lab project where we took silver nitrate mixed it in water and put a coiled copper wire in to the solution. I need to know why the solutions color changed when the reaction started. The color the solution turn to was blue. If you can answer this it would mean alot to me its a lab question due tomorrow thank you.

2007-03-04 15:43:06 · 2 answers · asked by big papy 3

Strontium90has a half life os 28 years, how long will it take for all of strontium 90 presently on Earth to be reduced to 1/32nd of its present amount

Could you explain how to do this question and is the answer 140>?

2007-03-04 15:42:04 · 4 answers · asked by Anonymous

2007-03-04 15:33:38 · 0 answers · asked by Amber S 1

I have a chemistry problem that I need some help with. I have the awnser(it is a practice prob from my practice book) but i am befuddled on the complete subject now. Help!!! the problem is


"How many unpaired valence electrons are there in a phosphourous atom[P] that has 15 electrons? (use shell models to deduce awnsers.)"


the awnser is

"Three. Two of phosphourous electrons pair up in the first shell and 8 pair up in the second. The remaining 5 occupy the third. Because the third shell has a capacity for 8 electrons, two are forced to pair up leaving 3 unpaired."


Ok...so I dont understand why 2 of the three cant pair up and just leave one by itself after all, alkali metals only have 1 unpaired electron.

And why do alkali earth have 2 unpaired? Cant the remaining two pair up?

2007-03-04 15:29:48 · 4 answers · asked by Anonymous

Experiment is at 450oC
Experiment Initial Rate (mol/L.sec) [H2] [I2]
1) 1.9*10E-23 0.0113 0.001
2) 1.1*10E-22 0.0220 0.0033
3) 9.3*10E-23 0.0550 0.0022
4) 1.9*10E-22 0.0220 0.0056

I noted that H2 and I2 seem to be inverse, what else do you see?

2007-03-04 15:16:45 · 2 answers · asked by Anonymous

How much H2O must be added to 74.5 g of
Ca(NO3)2 to form a 0.300msolution? Answer
in units of kg.

2007-03-04 15:15:36 · 1 answers · asked by dojorno5 2

How much solute is needed to make 1.49 L of
a 3.42 M solution of Ba(NO3)2? Answer in
units of g.

2007-03-04 15:14:45 · 3 answers · asked by dojorno5 2