Chemistry - December 2007

I have UV lights that I would like to put in a tube and block it's harmful UV rays. I plan to use a polycarbonate tube, but I'm getting conflicting answers on wikipedia if it 100% blocks harmful UV.

http://en.wikipedia.org/wiki/Polycarbonate
Above link it says polycarb resists UV fairly. (right and colum in yellow)
On the same page bellow the graph it says: 0% transmission at almost exactly 400 nm, blocking all UV light transmission."

Then here:
http://en.wikipedia.org/wiki/UV_light

It says under "Eye" paragraph. "Some plastic lens materials, such as polycarbonate, inherently block most UV."

What's the straight story on this?

2007-12-18 05:10:40 · 2 answers · asked by honeyroastedeggroll 1

Friendzzz.1)Why is it important 2 balance an equation?????
2)How do v balance an equation???Plzzz help wth the examples.
Any help would be appreciated!

2007-12-18 05:04:51 · 2 answers · asked by Anonymous

2007-12-18 04:20:29 · 5 answers · asked by Tristan E 1

A container contains 2 mol of H2 and 1 mol of O2. Write down the probability that all the H2 is in the leftmost 2/3 of the container and all the O2 is in the rightmost 1/3.

I don't need a numerical answer for this, but I'm having trouble conceptualize a correct expression that will solve this problem.

Thank you!

2007-12-18 04:01:41 · 1 answers · asked by elan_longterm_invest 2

The density of toluene (C7H8) is 0.867 g/mL, and the density of thiophene (C4H4S) is 1.065 g/mL. A solution is made by dissolving 17.0 g of thiophene in 250.0 mL of toluene.

(a) Calculate the mole fraction of thiophene in the solution.

(b) Calculate the molality of thiophene in the solution.

(c) Assuming that the volumes of the solute and solvent are additive, what is the molarity of thiophene in the solution?

2007-12-18 03:51:50 · 3 answers · asked by Karma564 2

2007-12-18 03:25:19 · 1 answers · asked by k,b 1

1)............... is the gaseous byproduct when sodium metal is added to ethanol

2)what type of orbital do the lone pair electrons of oxygen occupy in ethanol? ............
3)when two carbenes collide, they dimerize to give an ................
4)distillation of mixtures of ethanol and water cannot increase the ethanol content of the mixture above 95% because this solution boils at lower temperature than either pure ethanol or pure water . the term which describes this lower boiling point mixtures is ...............
fill in the blank plz, answer any question that u know
thanks already for whoever answers.
happpy holidays

2007-12-18 03:09:20 · 3 answers · asked by lscence 2

it is for a chemistry project that i really need help with

2007-12-18 03:07:33 · 1 answers · asked by Coopman17 1

2007-12-18 02:53:12 · 5 answers · asked by Xilion 3

2007-12-18 02:09:21 · 3 answers · asked by honey0002 1

2007-12-18 01:58:20 · 2 answers · asked by scardaropoli 1

...water, inside and outisde the gas collecting tube, are the same. Temperature is 17 degrees celsius. Barometric pressure is 720.0 mmHg. Convert the volume to that of dry gas at Standard temp and pressure (STP).

the answer is 21.8 mL but can someone explain please?
THanks

2007-12-18 01:22:06 · 3 answers · asked by Anonymous

Which of the following statements are CORRECT?

1.The atomic radii of transition metals decrease initially, then increase as one moves from left to right across a period of the periodic table.

2.The atomic radii of the period 6 transition metals are approximately 25% larger than the atomic radii of the period 5 transition metals.

3.The densities of the period 5 transition metals are greater than those from either the period 4 or period 6 transition metals.

a.1 only
b.2 only
c.3 only
d.1 and 2
e.1, 2, and 3

2007-12-18 01:17:20 · 1 answers · asked by Anonymous

1. (NH4)3PO4


2. Na2SO3


3. HNO2


4. N2O5

2007-12-18 00:57:56 · 2 answers · asked by Anonymous

Harmful or beneficial?

2007-12-18 00:44:49 · 1 answers · asked by Chris 2

thank you for your help again!

2007-12-18 00:34:33 · 6 answers · asked by safa s 1

I would like to know about polymer department research and which is the best

2007-12-18 00:27:09 · 2 answers · asked by Shahin H 1

what is the blank? and what does conduct really mean.... something that conducts electricity?

2007-12-17 23:58:57 · 7 answers · asked by choco 2

I am doing some tutoring and want to check that I am correct when I say: Ionic bonding only happens in salts.That this is always between a metal ion and a non-metal ion, and that ionic structures are always 'giant' (and therefore crystals)? Does ionic bonding happen in simple molecules and what are examples of this if so? Thanks!

2007-12-17 22:36:21 · 3 answers · asked by dippyandproud 2

Could some please name a few chemical solutions (ie: carbonate, bromide, hydroxide) which change over time. As in, their chemical compositions change so if they were to be used in a reactions lab, they would produce different reactions then if a new solution had been used.

2007-12-17 22:28:49 · 2 answers · asked by Neon 3

2007-12-17 18:53:27 · 3 answers · asked by duckieblueplanet 1

2007-12-17 18:05:10 · 10 answers · asked by Anonymous

2007-12-17 16:37:05 · 4 answers · asked by Anonymous

A 3.00 microliter standard sample of 50% 1-propanol and 50% n-butanol is injected and the results are below. 1-propanol is the internal standard. The peak areas are:
1-propanol: 6.550 cm^2
n-butanol: 5.321 cm^2

A 3.00 microliter unknown sample of 50% 1-propanol and an unknown mixture concentration of n-butanol is analyzed with the same gas chromatograph. The peak areas are:
1-propanol: 6.181 cm^2
n-butanol: 3.216 cm^2

Calculate the percent composition of the n-butanol in the unknown mixture. (hint, the total will not be 100%, there are other components in the sample).

2007-12-17 16:34:32 · 1 answers · asked by Lobster 4

Al + NH4ClO4 --> Al2O3 + AlCl3 + NO + H20

So stupid, I cannot believe this is in the text book. of all places..., I mean, NO isnt even a balanced molecule!!!!!

2007-12-17 16:16:54 · 5 answers · asked by mune_ga_arimasu_ka 2

2007-12-17 15:00:58 · 3 answers · asked by Willowjac 5

?

2007-12-17 14:48:26 · 1 answers · asked by Anonymous

A cell is bathed in a fluid. You notice that water is flowing out of the cell. In what kind of solution is this cell immersed - isotonic, hypertonic or hypotonic? I'm sort of confused on this one...

2007-12-17 14:44:33 · 4 answers · asked by Anonymous

- What are the initial and final radioactive elements of the decay series and the type of decay (α, β or γ radiation) of 210Po?
- How long is the half-life of 210Po? How long will it take to completely lose its radioactivity?

2007-12-17 14:36:37 · 1 answers · asked by muzuizui 2

my homework is to complete a crossword puzzle
and these were the hints,
1) Radioactive rocks have this property
(# of letters : 14)
2) element made when boron and a neutron collide
(# of letters: 9)
3) The parent atom from which astatine and a beta particle are produced
(# of letters:8)

2007-12-17 14:23:20 · 1 answers · asked by Rosie 2