Chemistry - November 2007

In a lab report, we were using Hess's Law to calculate enthalpies using a few reactions we did in class, one of which was magnesium in hydrochloric acid. The question was to explain why the change is exothermic.

What exactly is it about displacement reactions of metals in acids that makes them exothermic?


In this case,

Mg + 2HCl --> MgCl2 + H2 + xkJ

2007-11-18 03:45:06 · 4 answers · asked by Jeb 2

I'm working on my chem homework, and there are two questions that I can't find about in my notes:

27. Which metal is most likely obtained by the electrolysis of its fused salt?

a. Au
b. Ag
c. Li
d. Zn

29. Which of the following elements can form more than one binary compound with Oxygen?

a. sodium
b. magnesium
c. iron
d. calcium

If you could please explain the answers too so I can understand it I would be very grateful. Thank you in advance!

2007-11-18 03:44:09 · 1 answers · asked by Meggie Beth 3

2007-11-18 03:33:08 · 2 answers · asked by sathi 2

Using the Gibbs-Helmholtz equation (T = H / S), why do all compounds decompose into their individual elements if heated to high enough temperatures?

2007-11-18 03:20:16 · 3 answers · asked by Anonymous

tell me how to do this?thanks.

2007-11-18 03:05:59 · 4 answers · asked by jess r 1

2007-11-18 03:04:48 · 4 answers · asked by jess r 1

Hey!!! List One Or More And There Uses. Don't Worry If You Can't Find There Uses :)


Many Thanks x

2007-11-18 02:47:18 · 6 answers · asked by Anonymous

I think so because the equations would have to be SiH4 and the lewis dot structure would give you a s H on each side pulling equally in each direction and I think the electrons are equally shared. What do you think?

2007-11-18 02:35:03 · 5 answers · asked by steelhead3686 3

Na2C03+ HNO3 ---> Na2NO3 + H20 + CO2
this is as far as i got....
is there a gogd formula or something that can be used?
thanks!

2007-11-18 02:28:17 · 5 answers · asked by rogla 3

2007-11-18 01:54:15 · 4 answers · asked by Anonymous

O2(g) + 2H2(g) → 2H2O(g)

Give the mole fraction of all species present at the end of the reaction.

2007-11-18 01:12:26 · 1 answers · asked by Brian 1

Chemistry Multiple Choice: Help?
Please Help With the following Multiple Choice:

Which of the following is NOT a true description of gas behavior?
a) There is an inverse relationship between pressure and volume and for a fixed mass of gas confined at constant temperature
b) There is a linear relationship between temperature and volume at constant pressure
c) There is a linear relation between pressure and temperature at constant volume
d) For a fixed number of moles of a gas confined at constant temperature the product of pressure and volume is constant
e) The gas laws only describe correctly gas behaviors for pure gases and not mixtures of gases

14) Which gas law when extrapolated indicates that there is a minimum low temperature that nothing can be colder than?
a) Boyle’s Law
b) The constant volume law
c) The combined gas law
d) Charles’ Law
e) Avagadro’s Law

Any Help will be appreciated.
Thanx.

2007-11-18 00:46:38 · 2 answers · asked by Anonymous

2007-11-18 00:05:04 · 1 answers · asked by Ron G 1

Comment briefly on the relative values of ∆G standard of the dissociation reaction and the ∆Gf standard of ammonium carbamate in relation to the ‘thermal stability’ of the substance.

∆G standard = 20.01293819 kJ mol-1

∆Gf standard = 446.0129382 kJ mol-1

What do these values mean please?

2007-11-17 22:40:39 · 3 answers · asked by Anonymous

we did an experiment in our chem lab wherein we added grinded soda-lime and blended mongo and then heated it. We put moistened litmus paper at a tip of a stirring rod and it turned blue. The questions on our manual are confusing and i'm really having a hard time i need your help...

these are the questions:

1. What is the role of soda-lime in the reaction?

2. Write the chemical equations involved in:
a) reaction with soda-lime
b) reaction with litmus papers

3. why is the soda-lime test NOT considered a confirmatory test for the presence of nitrogen?

please.. i need infos.. i'm really confused.. >.<
thanks!

^_T kc

2007-11-17 22:15:03 · 3 answers · asked by kcwed23 1

2007-11-17 22:05:49 · 1 answers · asked by Denise 1

2007-11-17 22:05:30 · 0 answers · asked by grr 1

2007-11-17 22:05:17 · 5 answers · asked by Carmel 1

Procedure:

Obtain a piece of copper wire. Note the color of the wire and record your observation. Make a loop at one end of the wire and eat it to red hot. Allow it to cool and note the change in color of the wire.

Dip the heated copper wire in METHYLENE CHLORIDE Solution. Heat the loop and note the color imparted to the flame.

Reapeat the procedure using IODOFORM.

Results:
Both copper wires produced a green flame.

So, here are my questions:
1. What is the role of the heated copper wire in the reaction?
2. Is the beilstein test a conclusive test for a particular halogen? Why/not?
3. Give the principle involved in this test.

P.S. Thank you for those people who wouldn't flame this....

2007-11-17 21:15:24 · 2 answers · asked by Jed Stephen 3

2007-11-17 20:31:36 · 5 answers · asked by Muammar A 1

H2 + Cl2 >>> 2 HCl

Could someone please show me how to answer the question in full steps. This is seriously confusing. (TIA)

2007-11-17 20:08:05 · 1 answers · asked by xxxladyxxx 1

I have 2 quick problems that I need some assistance solving!

1. What is the corresponding wavelength of a neutron traveling at 4.56 x 10^4 m/s, whose mass is 1.00866 amu.

-The main part giving me trouble on this is how I should convert amu into a functional unit for the formula to solve for wavelength.

2. List the following in decreasing order of size: Ca, Ti4+, Sc3+
-I understand that atoms and ions grow larger through the periodic table as they move down and left, but am unsure when an electron moves from a charged state to a noble gas version.


Thanks in advance!

2007-11-17 19:45:38 · 3 answers · asked by Justin M 1

i need it for my investigatory project. anyone please help. how do i make a filter? just a simple one for pollution in the air.

2007-11-17 19:22:48 · 4 answers · asked by Anonymous

*tell me a website i can go to if u found an answer there

2007-11-17 18:49:37 · 1 answers · asked by Anonymous

I've been reading about the ocean segment of the carbon cycle... particularly about how the burning of fossil fuels and resulting CO2 on ocean water acidity affects the ocean's effectiveness as a carbon sink. Carbon dioxide, carbonic acid, bicarbonate, and carbonate ions interact with limestone and calcium carbonate in the ocean -- particularly dissolving calcium carbonate shells of mollusks... especially the planktonic ones.

It brings to mind soft-drinks and increased risk of bone fractures... I wonder if they are linked in some way. Anybody have some information? I haven't been able to find related info on the web. Thanks!

2007-11-17 18:44:46 · 2 answers · asked by Anonymous

I know the rxn
4NH3 + 5O2 -> 4NO + 6H2O

but does anyone have maybe a scanned img of the mechanism or a detailed explanation.

I started to say oxgen elections grab a pt2+ and then resonate to a + charge on the oxygen without the pt on it then the nitrogen free elections grab the positively charge oxygen and then oxygen electrons from another O2 grab off and H and the electrons go onto the N and stabalize it but from there im lost. thanks for the help

yes, I could have saved some lines and said oxidation of ammonia but it means the same thing as what I said in the description. I am doing a powerpoint presentation with this rxn and this will be more indepth rather than just showing "it is bc it is"

2007-11-17 18:35:08 · 2 answers · asked by thatoneguy 2

2007-11-17 18:21:31 · 3 answers · asked by Lara J 1

please explain.

2007-11-17 14:42:15 · 2 answers · asked by Shannen L 3

Typing a word document and don't know how to include the small clear circle before the c in degrees celsius. Please help.

2007-11-17 13:55:35 · 8 answers · asked by Anonymous

2007-11-17 13:44:35 · 2 answers · asked by Cyryen 1