Chemistry - March 2007

of 3.80 and 5.42 eV, and a value of gA of 0.0090 x 10-8 and 12 x 10-8 respectively. What is the most intense line for T=2000K and T=5000K? At what temp do the two lines have the same intensity?

2007-03-15 07:54:28 · 1 answers · asked by Hard Rocker 3

2007-03-15 07:40:41 · 8 answers · asked by ladona c 1

I have no idea how to do these 2 problems!

1.) The energy of a photon is 2.87 x 10^-19 J. What is the wavelength of the corresponding light?

2.) Neutrons are used to obtain images of the hydrogen atoms in molecules. What energy must be imparted to each neutron in a neutron beam to obtain a wavelength of 8.4 pm? Obtain the energy in electron volts (eV). Hint: 1 eV=1.602 x 10^-19.

I'm pretty sure you do them both the same way, with 2 having a little more work... maybe. I really have no idea!

If anyone could give me a hint or explain how to do it or ANYTHING at all I'd REALLY appreciate it!! Thanks so much!!!!

2007-03-15 07:39:15 · 6 answers · asked by Anonymous

50ml of water at 49.6ºC were mixed with 50ml of water at 25.1ºC in a calorimeter also 25.1ºC. the final temperature was 30.1ºC. assuming that neither the density of water nor its specific heat capacity change with temperature, calculate the total heat capacity of the calorimeter. density of water=1.00g/ml, specific heat capacity=4.18J/gK

2007-03-15 07:37:49 · 1 answers · asked by nik 1

2007-03-15 07:36:27 · 3 answers · asked by DODO 1

2007-03-15 07:18:41 · 3 answers · asked by DODO 1

2007-03-15 07:18:03 · 2 answers · asked by Brooke S 1

2007-03-15 07:06:33 · 1 answers · asked by sikandar3939 1

I have pentene and I need to add a carbon in order to make a carboxylic acid, but I don't remember the reaction to add a carbon.

2007-03-15 07:03:58 · 3 answers · asked by babykrisbach1 2

2007-03-15 07:01:58 · 4 answers · asked by DODO 1

but how much greater is it?
and how do you work it out?

2007-03-15 06:59:11 · 6 answers · asked by malibuisace 2

1. What is the name of the disease caused by Vitamin D defiency?

2.What is the name for young eels?

3.Which famous scientific husband was hit by bus?

4. What is the name of the female scientist who discovered the structure of DNA?

5.What is the name of alkane with 8 carbons?

6.What is the name for fear of school?

7. Which planet has 27 moons?

8. Who was the first to exceed the speed of sound?

9. 'W' is the symbol for what chemical element?

10. What is the name given for the study of fish?

11. Which nerve transmits visual information?

12. What is the S.I unit for force?

--- the first letter of the answers forms a word... what is it?

2007-03-15 06:51:19 · 5 answers · asked by Anonymous

70.0 mL of 0.100-M hydrogen cyanide (Ka = 6.20×10-10) is titrated with 0.100-M NaOH.

What is the initial pH of the hydrogen cyanide solution?


I have such a problem with titrating problems...Help please..

2007-03-15 06:36:54 · 3 answers · asked by Anonymous

A) Give the rate equation.
B) Give the overall order of the reaction (as a number).
C) Give the order of the reaction (as a number) with respect to B.
D) What is the order of the reaction (as a number) with respect to B, if B is in excess?
E) What is the overall order of the reaction (as a number), if B is in excess?

2007-03-15 06:31:48 · 4 answers · asked by Hard Rocker 3

H2 + 1/2O2 ----> H2O

I don't think it is because it would be difficult to get half a mole of O2 but I'm not sure. Also, is it reversible? Isn't it called electrolysis or something when you break apart water into hydrogen and oxygen? Thanks for your help!

2007-03-15 06:31:17 · 2 answers · asked by BeC 4

please help! also what is the relationship between pH and Ka?

2007-03-15 06:13:02 · 2 answers · asked by malasunas 3

2007-03-15 06:11:15 · 1 answers · asked by <3 1

2007-03-15 06:09:22 · 2 answers · asked by <3 1

2007-03-15 05:56:41 · 1 answers · asked by awalkwithdestiny 2

2007-03-15 05:50:00 · 1 answers · asked by <3 1

2007-03-15 05:38:52 · 2 answers · asked by *yawn* 2

2007-03-15 05:28:16 · 3 answers · asked by Anonymous

2007-03-15 05:25:37 · 20 answers · asked by Anonymous

I'm in high school, and I'm taking Chemistry this year, and I really don't get fusion and fission. Can someone help me out with these?

Which one is used to produce radioisotopes for science and medicine? Which one produces the greatest amount of energy per unit mass? Which one uses nuclear fuel, and which one uses lightweight nuclear fuel?

Thanks!

2007-03-15 04:51:27 · 9 answers · asked by JaNaLiEn 2

I am kind of having trouble with these problems...I get to a certain point then I'm stuck.

1. When 4.21 grams of hydroxide are added to 250 mL of water, the temperature rises by 4.14 °C. Assume that the density and specific heat of the dilute aqueous solutions are the same as those of H2O and calculate the molar heat of solution of potassium hydroxide.

**Would this eq be right?
q=(254.21g)(4.184J/gK)(4.14K)

2.Calculate the standard heat of formation of copper(I) oxide using the following data:
CuO → Cu + ½ O2 ΔH° = 157.3 kJ/mol
4 CuO → 2 Cu2 O + O2 ΔHo = 292.0 kJ/mol

2007-03-15 04:44:05 · 2 answers · asked by Jay 2

a.C3H8+O2=CO2+H2O+Energy
b.C3H8+502=3CO2+4H2O+Energy
c.C3H8+O2=3CO2+4H2O+Energy
d.C3H8+5O2=CO2+H2O+Energy
e.C3H8+3O2=CO2+H2O+Energy

2007-03-15 04:28:48 · 5 answers · asked by fran_tasha 1

Is this a thermodynamically possible reaction at T= 1173 K ?
2(Ca^2+) + TiO2 ---> (Ti^4+) + 2CaO
The ions and CaO are dissolved in the same liquid, but very dilluted.TiO2 is in solid state. DG needs to be calculated.
I don't give you my DG's for the participants, because may not be accurate. You can calculate ion's DG's useing their standard potentials. Thank you very much. Any answer will be very important for me. The closest one will be the best one.

2007-03-15 04:10:57 · 1 answers · asked by flyoverall 2

(assume the distance between them is 5x10 (-11)
meter, and the mass of electron is 9.1x10(-31) KG
a.1.2x10(-9)
b.2.5x10(-9)
c.8.0x10(-8)
d.9.1x10(-8)
e.16.3x10(-5)

2007-03-15 04:08:35 · 2 answers · asked by fran_tasha 1

2007-03-15 03:45:21 · 4 answers · asked by James 1

Reaction between NaHCO3 + HCl,

The chemical equation is

NaHCO3 + HCl --> NaCl + H2O + CO2

The question is
What form do these products take in the solution?
(hint are they ions or compounds?)

2007-03-15 03:30:45 · 2 answers · asked by on_gt 1