Chemistry - December 2007

e.g. at 280nm alanine is absorbing 0.160 of light, the path length is 1cm i used 0.1mM of alanine.
Any help would be priceless thanx

2007-12-08 06:46:00 · 1 answers · asked by Hulk 1

cobalt-60 is a beta emitter with a half-live of 5.3 years. Approximately what fraction of cobalt-60 atoms will remain in a particular sample after 26.5 years?

1. 1/5
2. 1/16
3. 1/26
4. 1/32
5. 1/64

2007-12-08 06:34:55 · 2 answers · asked by Kak D 1

other than online

2007-12-08 06:22:35 · 2 answers · asked by rémy613 3

when atoms of aluminum-27 are bombarded with alpha particles, a neutron and an element are produced. the particula isotope formed is

1. 31 14 Si
2. 30 14 Si
3. 31 16 S
4. 30 15 P
5. 31 15 P

2007-12-08 06:20:34 · 1 answers · asked by Shizzy D 1

2007-12-08 03:26:47 · 2 answers · asked by Anonymous

Thanks it is important plz help me. Thanks

2007-12-08 03:16:52 · 3 answers · asked by Anonymous

2007-12-08 03:06:11 · 2 answers · asked by Transfatboy 1

I have done an iodine clock experiment. The reaction is:

H2O2 + 2I- + 2H+ -----> 2H2O + I2

I have varied the concentrations of each to find the order with respect to each reactant. I have worked out the orders by plotting Ln(1/T) Vs Ln[concentration]. The gradient is the order.

Now i have to assess the errors involved in this experiment. I want to find an esimate for the error for the value for the orders.

How do i do this? Because i have varied the concentration alot of times so how to i find the over all error in the order?

Any help will be appreciated. Thanks

2007-12-08 01:21:10 · 1 answers · asked by JAGDEEP S 1

a) the same number of atoms
b) more atoms
c) less atoms
Please Support answer Thanks

2007-12-07 18:36:52 · 6 answers · asked by no clue 2

What is a good, cost-efficient way to measure conductivity?
It's for the science fair project of a 5th grader that I'm helping.
He needs to be able to measure the conductivity and get a number out of it that he can analyze. (No checking the brightness of a light bulb or the speed of a small motor.)
Thanks.

2007-12-07 18:26:42 · 1 answers · asked by Chris #326 1

2007-12-07 18:20:08 · 1 answers · asked by ANGELF311 1

They say to drink water every day, but can I drink tea instead? Or does it have to be pure water?

2007-12-07 17:17:38 · 7 answers · asked by Anonymous

a) 4
b) 6
c) 8
d) 10
e) 12

2007-12-07 16:26:05 · 2 answers · asked by peluc 1

2007-12-07 16:17:40 · 1 answers · asked by Anonymous

If 4.3 ml of benzaldehyde are mixed with 1.6ml of acetone, then calculate the hteoretical yield of dibenzalacetone in grams.

2007-12-07 16:16:32 · 5 answers · asked by Natiphy2007 1

2007-12-07 15:42:31 · 4 answers · asked by Anonymous

2007-12-07 13:16:03 · 1 answers · asked by Anonymous

I need to know the significantance of water.

If you drink it does it ...

Make skin lighter/healthy
Eliminate dandruff
Melts fat in boy

Someone let me know whats sup

2007-12-07 09:20:04 · 2 answers · asked by Anonymous

I am going back to school after 20 years out of high school...my first class is chemistry 100. I have a BBA but no experience with chemistry...any words of wisdom?

2007-12-07 08:31:47 · 6 answers · asked by BryaN 2

Calculate the ethalpy change in KJmol-1 of the following two reactions:
HI-----> 1/2H2 (g)+ 1/2 I 2 (g)
H2(g)+ I2-------> 2HI (g)

How do wrk this out, i can understand what's going on please tell how work this. It's not homework, i just practicing questions and can't do it. Thank you very much.

2007-12-07 08:30:25 · 1 answers · asked by Hi! 3

It is true that the complete combustion of a hydrocarbon can do more work than incomplete combustion. Compare the work ΔG done by the combustion of one mole of ethane undeer these conditions.
Incomplete combustion: 2 C2H6 (g) + 5 O2 (g) → 4 CO(g) + 6 H2O (g)
Complete combustion: 2 C2H6 (g) + 7 O2 (g) → 4 CO(g) + 6 H2O (g)

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

2007-12-07 08:19:33 · 1 answers · asked by abc 1

2007-12-07 08:14:30 · 6 answers · asked by Anonymous

19.) Potassium chlorate (kclo3) decomposes to form potassium chloride and oxygen gas. If 5.4 moles of potassium chlorate decompose, how many moles of oxygen could be produced?

20.) What mass of fecl2 could be produced from 35.0g of fe and excess hci if the balanced reaction is Fe + 2hci --> fecl2 + h2

please help me answer either one o the other...Somehow show me how i could do the work also...

2007-12-07 08:13:52 · 1 answers · asked by Waqas A 2

A solution contains 0.837M Li^+ and 7.32 X 10^-2M CO3^-2. What type of solution is this with respect to lithium Carbonate? Compare your Q and K. (Ksp=1.70 X 10^-3)
a. saturated
b. unsaturaed
c. supersaturated

can someone please help me answer this question? and show the answer is reached.
thank you

2007-12-07 08:07:46 · 2 answers · asked by abc 1

Oxidation of gaseous CIF by F2 yields liquid ClF3 an important flourinating agent. Use the following thermochemical equations to calculate the standard heat of reaction for the production of chlorine trifluoride (ClF3).
1) 2ClF(g) + O2 => Cl2O(g ) + OF2 (g) change in H = 167.5KJ
2) 2F2(g) + O2(g) => 2OF2(g) change in H = -43.5KJ
3) 2CLF3(l) + 2O2(g) => Cl2O(g) + 3OF2(g)
Based on your answer, how much heat is released (positive number) when 4.99 grams of ClF react with excess fluorine and oxygen gas to form ClF3 under standard conditions? Express your answer in kJ. Anyone know the answer? Please Help!

2007-12-07 08:04:52 · 3 answers · asked by David R 1

2007-12-07 08:01:59 · 3 answers · asked by joebeina 1

as i have to use it in a equation and im not sure how to work out what the chemical formula is

2007-12-07 07:54:43 · 18 answers · asked by joebeina 1

One compound contains 27.2 g of carbon and the other has 42.9 g of carbon. How can these data support the law of multiple proportions if 42.9 is not a multiple of 27.2?

2007-12-07 06:43:44 · 3 answers · asked by Sean D 2

Which of the following combinations would be the best to buffer an aqueous solution at a pH of 5.0?

a.CH3CO2H and CH3COO-, Ka = 1.8 × 10^-5
b.H3PO4 and H2PO4-, Ka1 = 7.5 × 10^-3
c.H2PO4- and HPO42-, Ka2 = 6.2 × 10^-8
d.HNO2 and NO2-, Ka = 4.5 × 10^-4
e.NH4+ and NH3, Ka = 5.7 × 10^-10

2007-12-07 06:10:15 · 2 answers · asked by Anonymous

2007-12-07 05:52:33 · 4 answers · asked by Daniel P 2