Chemistry - April 2007

The extinction coefficient for NADH is 6220 M-1 cm-1 at 340 nm. Calculate the following:
a. The absorbance of a 2.2* 10-5M sample in a 1-cm cuvet at 340nm.
b. The absorbance of a 2.2* 10-5M sample in a 1-mm cuvet at 340nm.
c. The absorbance of a 1mM sample in a 1-cm cuvet at 340nm.

2007-04-26 23:36:05 · 3 answers · asked by Anonymous

2007-04-26 23:17:01 · 1 answers · asked by bhaskarshome 1

in our laboratory experiment, we used a filter paper and dip it to different solutions then thrust it over the flame to observe color produced. why is it necessary to place the filter paper into the yellow region of the flame?

2007-04-26 22:57:24 · 1 answers · asked by Rubieanne 1

last week we performed a flame test experiment using a filter paper and a bunsen burner..we first folded the filter paper before we dip it into a solution and before we thrust it over the flame..why do we have to fold it..my teacher told us it is necessary but have not said why..

2007-04-26 22:53:28 · 2 answers · asked by Rubieanne 1

please explain in detail

2007-04-26 22:04:47 · 2 answers · asked by mathiphy 2

2007-04-26 21:54:05 · 2 answers · asked by mathiphy 2

Explain defferences between melting and dissolving.

Explain how mass is conserved

Use particle theory knowledge

Use idea of forces or energy in explanation

2007-04-26 21:49:52 · 2 answers · asked by meganqliu 1

calculate the mass of sodium acetate required to make 500 mL of 0.375 molar aq. soln. molar mass of sodium acetate is 82.0245 g/mol.

2007-04-26 21:48:51 · 2 answers · asked by mathiphy 2

In the process of synthesizing different drugs using combinorial chem and aminoacids, what are the "plastic beads" used for and why are they necessary? My chem prof does not do a very good job of explaining this so i would like a better explaination thanx!

2007-04-26 21:37:15 · 2 answers · asked by Anonymous

please explain in detail

2007-04-26 21:30:54 · 3 answers · asked by mathiphy 2

2007-04-26 21:08:41 · 1 answers · asked by nadya n 1

2007-04-26 19:24:45 · 2 answers · asked by mahirah 1

Either the strike-on-the-box kind, or the strike-anywhere kind, doesn't matter.

2007-04-26 19:18:05 · 5 answers · asked by Anonymous

I am sked to write a smll paper on this question. Can anyone help me with some details?

2007-04-26 19:02:09 · 3 answers · asked by raju a 1

pls. state the medical use

2007-04-26 18:31:19 · 8 answers · asked by Anonymous

The half-life of iron-59 is 45.10 days, so give your answer in days.

2007-04-26 18:26:49 · 2 answers · asked by VeggieGirl 2

what is the exess reagent for the following reaction given we have 2.6 moles of HCl and 1.4 moles of Ca(OH)2? Reaction: 2HCl + Ca(OH)2>>>>2H2O + CaCl2

2007-04-26 18:21:25 · 2 answers · asked by Anonymous

what is the limiting reagent for the reaction below given that you strat with 10.0 grams of Al and 19.0 grams of O2? Reaction: 4Al + 3O2>>2AlO3

2007-04-26 18:06:49 · 2 answers · asked by Anonymous

Im kind of confused on how to work this problem. Any help would be much appreciated.

Calculate the equilibrium constant for the decomposition of liquid water into hydrogen and oxygen gas at 25 degrees C.

Does anybody know the formula or how to work the problem?

2007-04-26 17:48:10 · 2 answers · asked by cs 2

1) A solution has a hydrogen ion concentration of 1 x 10^-6M. What is its pH?

2) What is the pH of a solution if the [H+] = 7.2 x 10^-9M?

3) What is the pOH of a solution if the [OH-] = 3.5 x 10^-2M?

4) What is the pOH of a solution that has a pH of 3.4?

2007-04-26 16:56:19 · 5 answers · asked by mz. * 1

2007-04-26 16:45:16 · 2 answers · asked by Anonymous

Steps to figure this out too

2007-04-26 16:38:29 · 2 answers · asked by strawberry 7 2

Approximate the heat of the reaction for the following equation using Hess's Law:

N2H4 (l) + H2O2 (l) --->N2 (g) + 4 H2O (l)
Change in Hrxn=?
(1) N2H4 (l) + O2 (G) --->N2 (g) + 2 H2O (l)
Change in Hrxn= -622.2kJ
(2) H2 (g) + O2 (g) ---> H2O2 (l)
Change in Hrxn= -187.8 kJ
(3) H2 (g) + 1/2 O2 (g) ---> H2O (l)
Change in Hrxn= -285.8 kJ

I was sick the day we did this in class so i have no idea... but this is how it is written in the work

2007-04-26 16:33:51 · 1 answers · asked by trust2400 3

2007-04-26 16:31:33 · 3 answers · asked by CIC 1

Determine the theoretical yield of silver hydorxide if 19.0 grams of AgNO3 if reacted with 19.0 grams of Ca(OH)2 and identify the limiting and excess reactants. Determine the percent yield if 16.2 g of silver hydroxide are obtained.

2007-04-26 16:11:14 · 1 answers · asked by trust2400 3

have occurred after 17 minutes?

2007-04-26 16:08:59 · 1 answers · asked by Paul C 1

after 10 minutes?

2007-04-26 15:54:25 · 2 answers · asked by Anonymous

The half-life of phosphorus-32 is 14.30 days, so give your answer in days.

2007-04-26 15:50:48 · 2 answers · asked by Paul C 1

HZ is a weak acid. An aqueous solution nominally 0.020M in HZ has a pH of 4.93 at 25 degrees Celsius. What is the Ka for HZ.
Please show all work so I can understand.

2007-04-26 15:45:09 · 2 answers · asked by tpsurvey1986 1

When heated, solid KClO3 forms solid KCl and O2 gas. A sample of KClO3 is heated and 226 mL of gas with a pressure of 749 mm Hg is collected over water, at 26°C. At 26°C, the vapor pressure of water is 25 mm Hg.

2KClO3(s) → 2KCl(s) + 3O2(g)

How many grams of KClO3 were reacted?

2007-04-26 15:15:23 · 2 answers · asked by Anonymous