Chemistry - May 2007

KHC8H4O4....if you have a source please show it, thanks for your help!

2007-05-07 16:36:35 · 2 answers · asked by Anonymous

If you hit the surface of copper wuth a photon of energy and find that the ejected electron has a wavelength of 1.89nm, what is the frequency in kilohertz of the incoming photon?

2007-05-07 16:35:13 · 2 answers · asked by peter s 2

when i converted, I got 0.08g which I do not think is right

2007-05-07 16:22:25 · 6 answers · asked by Julie 3

2007-05-07 16:20:33 · 1 answers · asked by Anonymous

A nice, simple answer would be nice.

2007-05-07 15:40:29 · 6 answers · asked by Anonymous

I need help with a couple Chemistry problems. 4 to be exact, but I will post the seperatley. They are apart of a study guide these are 4 out of 20. I have answered the other 16 but I am struggling with these. I have no idea how to do them. Please help.

What are the partial pressures for 28.9 g of Carbon dioxide CO2 and 23.5 g of oxygen O2, that are found within a steel cylinder with a total pressure of 1.5 atm?

2007-05-07 15:25:12 · 1 answers · asked by shane200388 1

2007-05-07 15:23:43 · 5 answers · asked by BAPS L 1

I need help with a couple Chemistry problems. 4 to be exact, but I will post the seperatley. They are apart of a study guide these are 4 out of 20. I have answered the other 16 but I am struggling with these. I have no idea how to do them. Please help.

A 10.0 L steel tank contains propane gas, C3H8 at 10˚C and a pressure of 1,750 mm HG. How many grams of propane are found with in the tank?

2007-05-07 15:23:35 · 2 answers · asked by shane200388 1

A voltaic cell utilizes the following reaction and operates at 298 K.

3 Ce4+(aq) + Cr(s) 3 Ce3+(aq) + Cr3+(aq)

1) What is the emf of this cell under standard conditions?


2) What is the emf of this cell when [Ce4+] = 1.5 M, [Ce3+] = 0.015 M, and [Cr3+] = 0.010 M?

3) What is the emf of the cell when [Ce4+] = 0.52 M, [Ce3+] = 0.83 M, and [Cr3+] = 1.3 M?

2007-05-07 15:17:43 · 1 answers · asked by Destiny E 2

What will be its volume at 963 mmHg and 122 celsius? Can anyone tell me the answer and how to solve it because I honestly need help because I have a test tomorrow in chemistry.

2007-05-07 15:16:11 · 6 answers · asked by msleisha08 2

A rock salt (NaCl), ice, and water mixture is used to cool milk and cream to make homemade ice cream. How many grams of rock salt must be added to water to lower the freezing point 10.0 degrees C.

Freezing point of water is 0.0 and Kf is 1.86

i just want to check my answers please.

2007-05-07 15:14:17 · 2 answers · asked by Anonymous

show work if u could plz

2007-05-07 15:11:41 · 1 answers · asked by bob l 1

Qualitative analysis studies require the use of a large number of chemical reagent, each of which must be treated with care. To illustrate this statment, list the reagents used to determine and confirm the presence of Ag+ ion in a sample, and describe the safety problems associated with each.

2007-05-07 15:10:21 · 1 answers · asked by Anonymous

I need a little help with this urea assignment:

Is urea basic or acidic? Explain why.

What are the sources of urea in waste water?

How is urea chemically changed to nitrate ions?

I will appreciate any help i can get. :)

2007-05-07 15:04:56 · 1 answers · asked by szymonsays 1

1.Neils Bohr’s contribution to modern atomic theory was the proposition that
A.each atom has a specific number of positive charges
B.an atom has electrons i n discrete energy levels
C.electrons have a definite mass that can be computed
D.atomic mass is determined by the number of protons and neutrons in an atom

2.How many grams of nitrogen are present in 2 moles of HNO3?
a.1
b.2
c.14
d.28

3.According to the periodic table, which of the following series of elements is ordered according to decreasing reactivity?
a.He, Cs, Si, Mg
b.Cs, Mg, Si, He
c.Si, H e, Cs, Mg
d.Mg, Si, Cs, He

4.How many moles of copper are equivalent to 3.44 ×1023 atoms of copper?
0.571 moles
a.1.75 moles
b.5.41 × 1021 moles
c.5.71 × 1022 moles

5.What is the molar mass of Al(NO3)3?
a.57 g/mol
b.103 g/mol
c.165 g/mol
d.213 g/mol

2007-05-07 14:41:00 · 2 answers · asked by Anonymous

What apparatus etc do i need to find out the purity of a substance - ethyl ethanoate specifically.

Also will the melting point be able to determine the purity? If yes will it be as accurate?

2007-05-07 14:26:55 · 1 answers · asked by Anonymous

NO(g) + O3(g) ------> NO2(g) + O2(g)

usually I would look for the phase changes etc. to figure out the sign (+ or -) of the entropy change, but in this reaction molecules arent breaking into smaller pieces, and there are the same number of moles gas on either side....
Can anyone help?
Thanks

2007-05-07 14:04:04 · 2 answers · asked by Gabriel R 1

2007-05-07 13:52:45 · 1 answers · asked by Anonymous

I'm not even sure if some of these elements exist, but my chemistry teacher offered extra credit if we could find these. If you don't know, but you know the names of these, that would be appreciated too.

MnO3
Ba(OH2) - H2O (hydrate) - do these have the detla H and delta S with or without a hydrate?
NH4OH
Ba(NO3)2

2007-05-07 13:51:07 · 1 answers · asked by Elizabeth 2

if u can answer any or all of these questions about the element flourine fromt the periodic time table than that would be very helpful, thanks.
is there any obscure ways that this element is used?
Is there any form of this element that people eat?
Are there any forms of this element that are dangerous for people to eat?
Can this element be lethal?
and any other information that might be useful or interesting about flourine, thanks!

2007-05-07 13:39:22 · 4 answers · asked by Anonymous

This is a question in my chem lab.

The carbon dioxide dissolved in carbonated beverages is in equilibrium with the air inside the container. Explain why the beverage becomes "flat" when the container is opened?

2007-05-07 13:38:53 · 4 answers · asked by Anonymous

What is an example of an metalloid, and what everyday item contains alkaline earth hydroxide?

2007-05-07 13:31:15 · 1 answers · asked by Immortal Syther 1

What are the common reactions, oxidation-reduction potential, crystalline forms, combustability, acid/base properties, and common bond types of silver

2007-05-07 13:28:02 · 2 answers · asked by animegeek91 2

I'm thinking I need the M1xV1=M2xV2

2007-05-07 13:10:41 · 2 answers · asked by foxtrot 3

Determine how many dm3 of CO2 at STP can be produced from 15.7 g of Fe2O3 according to the following equation:

Fe2O3(cr) + 3CO(g) → 2Fe(cr) + 3CO2 (g).

2007-05-07 13:02:30 · 1 answers · asked by San Fran Kid 2

1. The solubility of most liquids is NOT greatly affected by temperature. Explain.

2. Give 2 ways the solubility of gases in water is different from that of solids

2007-05-07 13:00:23 · 1 answers · asked by Anonymous

2007-05-07 12:44:22 · 1 answers · asked by candy 2

2007-05-07 12:28:21 · 2 answers · asked by mom 4

Cyclohexene + Bromine  dibromohexane
C6H10 + Br2  C6H10Br2

2007-05-07 12:23:17 · 2 answers · asked by Anonymous

What are the componets in lead paint that makes it seperate? I need this question for my science class...


Help?
Please and thank you.
-E

2007-05-07 12:20:13 · 1 answers · asked by E D 1