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Chemistry - January 2007

[Selected]: All categories Science & Mathematics Chemistry

and what is crystal field theory????????????

2007-01-21 20:52:29 · 1 answers · asked by Anonymous

Hi!
How would you prepare Iron Pyrites, a.k.a Iron Sulphide, Fool's Gold, FeS2, in the lab???

2007-01-21 20:46:17 · 3 answers · asked by Fiction B 2

What is it for? Is it important?

2007-01-21 20:24:26 · 1 answers · asked by chemelle 2

A drawing of the timeline would be much appreiated

2007-01-21 19:38:43 · 1 answers · asked by Ang3liine Kang 1

The water what I'm use for drinking was tested for its mineral contents. pH is 8.3 and it fails for acidity, alkalinity, Calcium, magnesium, nitrates, sulphates, chlorides. its conductivity is 500.

2007-01-21 19:37:00 · 2 answers · asked by Kannan 1

The comparisons between the models of atoms

2007-01-21 19:36:25 · 5 answers · asked by Ang3liine Kang 1

Consider a 5.313 g mixture of FeO and Fe3O4. You react this mixture with an excess of oxygen to form 5.749 g Fe2O3. Calculate the percent by mass of FeO in the original mixture.

2007-01-21 18:47:47 · 1 answers · asked by Moe 2

Consider a 5.313 g mixture of FeO and Fe3O4. You react this mixture with an excess of oxygen to form 5.749 g Fe2O3. Calculate the percent by mass of FeO in the original mixture.


help please

2007-01-21 18:28:55 · 1 answers · asked by Moe 2

i have mercury in a closed plastic container for about 6 years. I got that mercury from my school. We use to play with that.... ok anyway!!
My question is: Is it safe to have at home?I mean does it cause any reaction? or something like that? or astrologically safe? ... ?
all these years these questions never raised in my mind..
now i just want to know.....

thanks...

2007-01-21 18:17:16 · 13 answers · asked by ColD fIRe! 1

How many atoms of nitrogen are present in 3.93 g of each of the following?
1.)calcium nitrate
2.) dinitrogen tetroxide

2007-01-21 17:41:26 · 2 answers · asked by Moe 2

K4Fe(CN)6 + KMnO4 + H2So4 --> KHSO4 + Fe2(SO4)3 + MnSo4 + HNO3 + CO2 + H2O.

the numbers are actually small subscripts. Kay! thanks!

2007-01-21 17:22:00 · 5 answers · asked by Anonymous

Magnesium can be used as a "getter" in evacuated enclosures, to react with the last traces of oxygen. (The magnesium is usually heated by passing an electric current through a wire or ribbon of the metal.) If an enclosure of 0.376 L has a partial pressure of O2 of 3.50 10-6 torr at 26°C, what mass of magnesium will react according to the following equation?

2 Mg(s) + O2(g) 2 MgO(s)

2007-01-21 17:17:11 · 1 answers · asked by nickname 3

I am not good at science so I need some help! I had my elementary students list examples of physical changes. Their book listed water changing to ice or steam as one, or cutting or shaving wood. I read somewhere that physical changes can be reversed... but if I cut up a piece of paper, I can't reverse it without using tape or something. So what am I missing here? And as far as the responses I got, there were some clever/slightly deranged kids. One said animals, when they die. They're still animals. Or if you cut up a dog, it's still a dog. Or if you add salt to water, the salt is still there. Which confuses me- if you add kool aid mix to water, you dont have water anymore, you have kool aid. Can it be reversed? And lastly, someone said growing, like a baby growing to be an adult. Does that make sense? But the change from a seed to a flower would be chemical change, yes? Thanks for your help science people.

2007-01-21 16:35:53 · 6 answers · asked by Janet R 1

2007-01-21 16:34:19 · 2 answers · asked by sandeep singh 1

I don't get it. It's just a joke, or there's scientific evidence? Gimme an explain plz. thx

2007-01-21 16:20:23 · 6 answers · asked by Stanley R 2

The OH radical disproportionates according to the elementary chemical reaction OH + OH H2O + O. This reaction is second order in OH. The rate constant for the reaction is 2.0 x 10-12 cm3/molecule · s at room temperature. If the initial OH concentration is 1.0 x 1013 molecules/cm3, what is the first half-life for the reaction?

2007-01-21 16:19:57 · 2 answers · asked by jasmine m 1

Refer to the gas-phase decomposition of ethylene chloride:

C2H5Cl products

Experiment shows that the decomposition is first order.

The following data show kinetics information for this reaction:

Time (s) ln[C2H5Cl] (M)
1.0-1.625
2.0-1.735
What is the rate constant for this decomposition?

2007-01-21 16:18:48 · 2 answers · asked by jasmine m 1

The highly radioactive plutonium in nuclear waste undergoes first-order decay with a half-life of approximately 24,000 years. How many years must pass before the level of radioactivity due to the plutonium falls to 1/128th (about 1%) of its original potency?

2007-01-21 16:18:18 · 4 answers · asked by jasmine m 1

and have the same number of significant figures.

2007-01-21 16:05:13 · 9 answers · asked by Heavy Metal 3

Lets just say, That the formula for burning fuel (heptane in this case) is,
C7H16+11(O2)>7(CO2)+8(H2O)
Air wieghs 1.2kg per cubic metre
it is 23% O2 by mass
Heptane is 679.5g per litre

2007-01-21 16:00:56 · 1 answers · asked by Roy W 2

the pH of a 0.063 M solution of HBrO is 4.95. Calculate Ka.

2007-01-21 15:47:45 · 1 answers · asked by blu_pineappl3 3

2007-01-21 15:26:10 · 2 answers · asked by arggg 2

2007-01-21 15:12:17 · 4 answers · asked by hinnie22001 1

Lets test highschool chemistry. Its been a while for me.

2007-01-21 15:11:28 · 3 answers · asked by Roy W 2

I can't seem to find the answer to this anywhere. Could a chemistry expert help me out?

2007-01-21 14:57:21 · 6 answers · asked by Tres S 2

2. Vitamin C has a formula of C6H8O6.
a. The recommended daily dose of vitamin C is 60 mg. How many moles are you consuming if you ingest 60 mg of the vitamin?
b.A typical tablet contains 1.00g of vitaminC. How many moles of vitaminC does this represent?
c. When you consume 1.00g of vitaminC, how many oxygen atoms are you eating?

Please, any help with this question will be greatly appreciated; if possible show the steps you did to get the answer.

2007-01-21 14:56:14 · 4 answers · asked by j a 1

a. before
b. after
c. neither a or b
d. both a and b

2007-01-21 14:53:09 · 7 answers · asked by hinnie22001 1

I need definition, and example.
Properties of metals,Properties of nonmetal,Metallic bond,Covalent bond,Ionic bond

2007-01-21 14:47:24 · 1 answers · asked by Anonymous

fedest.com, questions and answers