Chemistry - November 2007

or at least perhaps minimizing this

2007-11-17 13:42:25 · 1 answers · asked by jamie 1

2007-11-17 13:40:21 · 1 answers · asked by jamie 1

From precipitation, filtration, decantation and evaporation which method is more effective?

2007-11-17 13:38:21 · 6 answers · asked by jamie 1

A.) SO2 is an important oxide of sulfur. The critical temperature of SO2 is 158 ºC and the critical pressure is 78.0 atm. Predict if SO2 can be liquefied by applying pressure at 180º C. Explain your answer

B.)Carbon disulfide, CS2, is a volatile flammable liquid. It has a vapor pressure of 400.0 mmHg at 28.0 ºC and 760 mmHg at 46.5 ºC. What is the enthalpy of vaporization of CS2?

C.) Metallic gold forms cubic crystals whose unit cell has an edge length of 407.9 pm. The density of gold is 19.3 g/cm3. Calculate the number of gold atoms in a unit cell. What type of cubic lattice does gold have (FCC or BCC or SC)?

D.) Classify the following according to the forces of attraction (intermolecular forces) that exist between these solids a) solid ammonia, NH3, b) cesium Cs, c) Cesium iodide CsI, d) silicon Si

E.)Arrange the following in the order of increasing boiling point
i) CH3OH
ii) CH2OH----CH2OH
iii) CH3----CH3
iv) CH4

2007-11-17 13:34:00 · 1 answers · asked by Hellos 1

i'm doing a science experiment to see if oil will spread faster in fresh water or salt water, but i dont know what to do with the oil when im finished. please help!

2007-11-17 13:33:33 · 18 answers · asked by Anonymous

2007-11-17 13:19:44 · 4 answers · asked by GoingChemCrazy 2

2007-11-17 13:08:59 · 6 answers · asked by Anonymous

ionic, ionic compounds, covalent, covalent compounds, metallic, metallic compounds

and also how do you identify a covalent network

2007-11-17 13:03:27 · 1 answers · asked by Anonymous

ok guys, we did a calorimetry kind of thing lab and we're supposed to measure the heat of neutralization.

In this equation:
NaOH + HCl ---> NaCl + H2O

first we have to find moles of water right? cuz the heat of neut is kj/mol of water formed.

What i have is: 50 mL of 2 M NaOH, and 40 mL of 2 M HCl.
ok so my question is, how do i calculate the number of moles of water??? is it the same as that of HCl?? plz any clarifications would be greatly appreciated!!

2007-11-17 12:52:50 · 2 answers · asked by Curious 1

1.Why do you add HCl to the mixture of BaCl2 and Na2SO4?

2.What are the factors that favour the formation of BaSO4 crystals?

3.How do you check the purity of BaSO4 crystals formed?

4.How do you improve the purity of BaSO4?

2007-11-17 12:49:29 · 1 answers · asked by kiko 1

Chemistry stuff..
Thanks in advance! =]]

2007-11-17 12:39:55 · 2 answers · asked by bro..ken.. h e a r t 1

a ridgid 8.2L flask contains a mixture of 2.5 moles of h2 , .5 mol of O2 and sufficent Ar so that the partial pressure of Ar in the flask is 2.00 atm. the temp is 127 C.

a. calculate the total pressure in the flask
b. calculate mole fraction of H2 in the flask
c. calculate density ( in g L-1) of the mixture in the flask

the mixture in the gas is ignited by a spark, and the reaction represented below occurs untill ne of the reactants is completly comsumed.

2H2 (g) +O2 (g) ----> 2H2O(g)

d. give the mole fraction of all species present in the flask at the end of the reaction.


i get the total pressure i just dont know how to do mole fraction.

2007-11-17 12:15:14 · 2 answers · asked by Help?? 2

gas fuel....uses in the periodic table of elements

2007-11-17 11:48:11 · 3 answers · asked by honeyjoe 1

A) A "dead" 12-Volt lead/acid storage battery has 4.40 g of PbSO4 (molar mass = 303.3 g), deposited on its electrodes. To recharge it, a ``trickle charger" is attached to the Pb anode that supplies 0.280 amperes of current at a voltage of 13.0 V. Calculate how much time it would take to convert all the PbSO4 back into SO42- ions in solution.

B) How long would it take to electrodeposit all the Cu2+ in 0.300 L of 0.250 M CuSO4 solution with an applied potential difference of 0.275 V and a current of 2.65 amperes? Enter your answer in minutes.

thanks a lot!

2007-11-17 10:40:14 · 2 answers · asked by Peter 2

2007-11-17 10:37:22 · 7 answers · asked by leechy1988 1

2007-11-17 10:34:55 · 3 answers · asked by hate mi kill mi nam mi raw !!! 2

2007-11-17 10:21:16 · 3 answers · asked by Anonymous

would you normally expect ∆H° to be positive or negative for a voltaic cell? Justify your answer.

can anyone please help me answer this question?
thanks

2007-11-17 10:10:39 · 1 answers · asked by abc 1

Calculate the voltage of the following cell:
Zn │ Zn^2+ (0.10M) ║ Cu^2+ (0.40M) │ Cu

can anyone please help me solve this problem? and show how it is done.
thank you

2007-11-17 10:05:06 · 1 answers · asked by abc 1

If increasing the concentration of a reducing or oxidisng agent increases its 'reducing' or 'oxidising' power why does the redox potential plateau once you get to a very high concentration? Why does it not continue to get higher/lower with increasing concentration of the solution in question?

2007-11-17 09:53:36 · 1 answers · asked by Anonymous

I am doing some work on redox reactions and I was wondering if anyone knows the half redox reaction when H2O2 is acting as an oxidising agent?

And does this half reaction depend on what it is reacting with or is it independent as long as it is oxidising something?

Thanks

2007-11-17 09:44:40 · 2 answers · asked by Anonymous

Calculate the pH of a 1.00 L solution which is made up of 0.043 mol acetic acid and 0.020 mol sodium acetate. (Ka for acetic acid is 1.8x10-5.)

2007-11-17 09:29:51 · 3 answers · asked by Anonymous

I'm looking specifically for the Keq value (equilibrium constant) for the reaction Fe3+ + SCN- ---> FeSCN2+ at around 25C

Anyone know where I can find this out? I tried google but didn't have much luck but maybe thats just me

2007-11-17 09:27:05 · 2 answers · asked by KM 2

Please explain quantum numbers! I know what each of the numbers means, but how do you identify an element based on a set of numbers. So, what does the set n=1 l=0 and m1=-1/2 tell me?

2007-11-17 09:24:44 · 2 answers · asked by Anonymous

Hi, we performed a calorimetric lab in which we did two separate experiments. In the first one we reacted Mg with HCl and in the second one we reacted MgO with HCl. We had to find out their molar enthalpies.
One of the questions are - Explain why and how your calculated enthalpies of reaction would be inaccurate if the surface of the magnesium ribbon had a coating of MgO

2007-11-17 09:08:16 · 1 answers · asked by Apoorva K 1

I'm going to be filming a video for a project in class, and my partners and I need a fog effect for the video. We're trying to keep it low budget so a fog machine is out of the question. We'll be filming really soon, so does anyone know if I can just store it in a cooler at room temperature? Also, we're buying about 2 pounds worth. Anyone know how to make the most of it?

PS The video is about 2 minutes long, but we're buying a little extra in case we have to do multiple takes

2007-11-17 08:52:50 · 4 answers · asked by agiel777 2

1. What is the wavelength of a 19F+ ion which is moving with a speed of 4.255x10^5 m/s?

I come up with 8.2001x10^-41m but the choices available are:
4.936x10^-20m
4.936x10^-17m
4.936x10^-14m
1.484x10^-29m
1.484x10^-26m

2007-11-17 08:35:33 · 1 answers · asked by S281 2

Copper metal was just dipped into acid, it was not heated or anything. can someone give me a easy explanation? thanks

2007-11-17 08:32:18 · 4 answers · asked by purplelightning92 4

What are the known isotopes of potassium, and what is the most abundant?

2007-11-17 08:23:31 · 2 answers · asked by primaballerina30058 1

A buffer containing 1.0564 M of acid, HA, and 0.1416 M of its conjugate base, A-, has a pH of 3.30. What is the pH after 0.0017 mol NaOH is added to 0.5000 L of this solution?

2007-11-17 08:23:17 · 1 answers · asked by Ecka 1