Chemistry - October 2007

2007-10-29 02:33:34 · 1 answers · asked by Faby 1

I need to know for a science project.
Additional information would be appreciated

2007-10-29 02:32:49 · 4 answers · asked by ZachH 1

2007-10-28 23:36:48 · 3 answers · asked by fuburyder14 1

i made a standard blackpowder mix but when i tested it, it took a long tome to burn and there were yellow blobs like solidified sulfur. is my potassium nitrate unpure or is the sulfur actually plastic or something else?

2007-10-28 20:45:40 · 1 answers · asked by trigva2004 2

2007-10-28 18:07:27 · 2 answers · asked by Anonymous

I need to know for a presentation tomorrow.

2007-10-28 17:31:37 · 3 answers · asked by bigmax_34 1

Can anyone help me out with this question??
The heat capacity of a bomb calorimeter is determined to be 5.718 kJ/C. 1.350g of lactic acid (HC3H5O3) is burned. The temperature of the calorimeter increases from 24.00 C to 27.59 C as a result of this combustion. Calculate the heat of combustion per mole of lactic acid.

2007-10-28 17:17:02 · 1 answers · asked by Anonymous

2007-10-28 17:00:09 · 3 answers · asked by Angel 2

Douglasite is a mineral with the formula 2 KCl·FeCl2·2 H2O. Calculate the mass percent of douglasite in a 468.4 mg sample if it took 37.20 mL of a 0.1000 M AgNO3 solution to precipitate all of the Cl - as AgCl. Assume the douglasite is the only source of chloride ion.

2007-10-28 16:20:33 · 1 answers · asked by mm 1

Can anyone help me with this and explain to me the whole procedure and reasoning of it? also what is the difference between pi and sigma bonds?

2007-10-28 16:17:49 · 1 answers · asked by metalmonkey71 1

5.23 g of hydrazoic acid ( HN3 ) is added to water to make a final solution of 408 ml.
What is the pH of the solution ?

Use Ka = 1.90 x 10-5 at 25.0oC.

2007-10-28 16:16:53 · 1 answers · asked by Nicole G 2

biologr class

2007-10-28 16:13:13 · 4 answers · asked by Anonymous

Is the cathode the steel case, or is it the Oxide (e.g. Mercury Oxide)?

2007-10-28 15:06:47 · 2 answers · asked by dani 1

In his explanation of the threshold frequency in the photoelectric effect, Einstein reasoned that the absorbed photon must have the minimum energy required to dislodge an electron from the metal surface. This energy is called the work function () of that metal. What is the longest wavelength of radiation (in nm) that could cause the photoelectric effect in each of the following metals?

(a) Tantalum, = 6.41 10-19 J

(b) Silver, = 7.59 10-19 J

(c) Tungsten, = 7.16 10-19 J

2007-10-28 14:48:35 · 1 answers · asked by Anonymous

Covalent bonds in a molecule absorb radiation in the IR range and vibrate at characteristic frequencies.

(a) The C-O bond in an organic compound absorbs radiation of wavelength 9.7 µm. What frequency (in s-1) corresponds to that wavelength?

(b) The H-Cl bond has a frequency of vibration of 8.634 1013 Hz. What wavelength (in µm) corresponds to that frequency?

2007-10-28 14:42:12 · 1 answers · asked by Anonymous

Calculate the energy difference (E) for the photon absorbed when a hydrogen atom undergoes a transition from n = 1 to n = 5 for 1 mol H atoms.

2007-10-28 14:31:33 · 1 answers · asked by divastr186 2

2007-10-28 14:29:35 · 7 answers · asked by Anonymous

2007-10-28 14:21:26 · 17 answers · asked by James the Just 3

A bottle of wine, which was analyzed for its tritium (3H) content, was found to contain 3.20% of the tritium that was originally present when the wine was bottled. How old (in years) is the bottle of wine? (The half-life of tritium is 12.3 yr.)


and



The half-life of 131I is 8.10 day.
Calculate how much time it would take for an isolated quantity of 131I to decay by 23%.

2007-10-28 14:21:07 · 1 answers · asked by thiswasjustforphysics 3

Why do chemists tak the rate of reactions near the beginning of a reaction?

2007-10-28 13:59:57 · 1 answers · asked by Anonymous

specific heat capacity of water is 4.18 J/g*C, molar mass of NaOH is 40 g/mol, molar mass of water is 18 g/mol
the formula for molar enthapy is Q/mol.
the formula for Q is mass* change in temp*specific heat capacity.

2007-10-28 13:49:38 · 2 answers · asked by valentina 1

I need to calculate the vapour pressure of of water in an experiment I have done for chemistry, and all I have is the tempurature of the water in the particular flask that I am calculating the pressure for, but I don't know how to go about calculating it in terms of Torr.

2007-10-28 13:42:28 · 1 answers · asked by Jaclyn 1

I have to calculate the concentration of the NaOH solution I used in a titration lab from my data. So my volume was 0.02830L and the amount of moles was 0.1025mol. Then I divided the moles over litres to get 3.6mol/l. But in the titration it was the volume of NaOH used to titrate 10.00ml of 0.15M H2C2O4 so now I'm confused because it took 28.30mL to titrate the oxalic acid. Would I have to include the other amounts (10.00ml of 0.15M H2C2O4) and if yes how would I do that?

2007-10-28 13:31:49 · 1 answers · asked by <3DA<3 1

2007-10-28 13:17:07 · 1 answers · asked by =D<333 2

If the electron is the smallest possible unit of matter, what is in between them and what is that made up of?

2007-10-28 13:06:54 · 2 answers · asked by Anonymous

C is 92.3% and Hydrogen is 7.7%, how do you calculate its simplest formula which is just CH from that?
thanks if you can help.

2007-10-28 13:01:50 · 1 answers · asked by Boo Radley 4

Can anyone show me how to do this?

2007-10-28 12:55:27 · 5 answers · asked by Anonymous

My teacher assigned us to come up wih a procedure for decomposing baking soda. The problem is I dont know when to tell that all of the gaseous substance has been left and baking soda is left in its purest form. Does anyone have any suggestions?

2007-10-28 12:54:26 · 4 answers · asked by Anonymous

A solution contains 0.405 g of oxalic acid, H2C2O4.2H2O, in 500 mL. What is the molarity of this solution? What is the normality of this solution with respect to the following reaction:
H2C2O4 (aq) + 2NaOH (aq) --> Na2C2O4 (aq) + 2H2O (l)

2007-10-28 12:10:41 · 1 answers · asked by Anonymous

Solvent: para-dichlorobenzene
Freezing point of pure solvent: 53.02 C
Mass of unknown substance: 2.04 g
Freezing point depression constant: 7.1 C/m
Mass of para-dichlorobenzene: 24.80 g
Freeezing point of solution: 50.78 C

Calculate molar mass of solute??

I got something in the 200s...

2007-10-28 12:10:23 · 1 answers · asked by Bao Pham 3