Chemistry - September 2007

White phosphorus, P4, is prepared by fusing calcium phosphate, Ca3(PO4)2, with carbon, C, and sand, SiO2, in an electric furnace.


2Ca3(PO4)2(s) + 6SiO2(s) + 10C(s) ==> P4(g) + 6CaSiO3(l) + 10CO(g)


How many grams of calcium phosphate are required to give 36.5 g of phosphorus?

2007-09-24 18:24:03 · 2 answers · asked by Joe C. 1

Ok I've got less than 1 hour to answer this question, I've got 6.42x10^-3 mol of Cu^+2, it takes 1.61 mL of 16.0 M HNO3 to completely dissolve this.

If I add 5 mL 16.0 M HNO3 to the already dissolved Cu in HNO3, how much 4.00 M NaOH will be required to neutralize the acid AND turn all the Cu+2 into Cu(OH)2???
Answers I know are incorrect:
2.32x10^-2 L
1.32x10^-2 L
2.96x10^-2 L

Help within the next hour would be SOOO amazing, I would be so grateful!

2007-09-24 17:43:14 · 1 answers · asked by Flubleah 1

2007-09-24 15:06:10 · 2 answers · asked by Elvis P 1

A)The energy emitted by radioactive isotopes can break bond and cause molecular damage in cells.
B)The Nuclei of radioactive isotopes are unusually stable, but the atoms tend to lose electrons.
C)When given a choice between radioactive and nonradioactive isotopes of the same atom, living cells are more likely to incorporate the radioactive isotopes into their structures.
D) The tracers typically used for diagnosoing medical problems remain radioactive in the body for a number of years, but give off very low levels of radioactive energy.
E) ALL of the choices are true.

2007-09-24 14:27:44 · 2 answers · asked by Travelingstar 1

i have answers to all of the questions except the following
1.what did the early greeks think all things where made of
2.what was one of the earlyest forms of chemistry
3.what was arranged into a systematic cahrt by dmiri mendellev
4.what did alchemists tri to make metals such as lead and iron into


well that is it and i would really apreacieate your help

2007-09-24 14:25:36 · 1 answers · asked by Steven O 2

2007-09-24 14:07:19 · 2 answers · asked by Anonymous

2007-09-24 14:06:17 · 4 answers · asked by manzz 1

tomorrow i am teaching my class about matter and the 3 states of it which are solids, liquids, and gases. my teachers book says to use vanilla extract as a gas, but it is a liquid. so how do i present this to them with out getting tons of questions. I NEED TO BE ABLE TO TELL WHY VANILLA EXTRACT IS A GAS!!! HELP!!!

2007-09-24 13:44:49 · 12 answers · asked by mshaw1986 2

2007-09-24 13:05:48 · 2 answers · asked by noyb 1

a mixture of cyclopropane gas and oxygen is used as an anesthetic. Cyclopropane contains 85.7% C and 14.3 % H by mass. At 50 degrees celcius and .984 atm pressure, 1.56 g cyclopropane has a volume of 1.00 L. What is the molecular formula of cyclopropane?

2007-09-24 13:03:26 · 3 answers · asked by diamond 3

2007-09-24 12:48:54 · 1 answers · asked by r-dee 3

2007-09-24 12:13:43 · 1 answers · asked by Anonymous

I have no idea what this is asking. There are 16 problems askng for the mathematical meaning of different abbreviations (such as km, Mm, g, kL, cl, etc) and I don't know what do. Please help. Thank you!

2007-09-24 11:37:37 · 10 answers · asked by Anonymous

Ideas?
And how to write a good lab report!?
I need a solid idea for it that is exciting and scientific at the same time (and reasonable) (i dont have acess to chemicals)

2007-09-24 11:10:07 · 1 answers · asked by Anonymous

Comparing the relative acidity strengths of aniline and a secondary amine (drawn as a "cyclohexane" where one C has been removed and replaced by an NH). The answer is that aniline is a stronger acid than the secondary amine:
Thanks to resonance, the acidity of aniline is eight powers of ten stronger than the secondary amine.
I do not understand the explanation given. Other than the typical resonance found in the benzene ring, I can't find another resoance strucutres for either!

Thanks for your help in advance!

2007-09-24 10:37:44 · 3 answers · asked by Anonymous

2007-09-24 09:30:38 · 1 answers · asked by Anonymous

Kc = .00463
T = 800 K
for the reaction:

COCl(sub. 2)(g) <=> CO(g) + Cl(sub. 2)(g)

Calculate the equilibrium partial pressure of all the components, starting with pure COCl(sub. 2) at 0.760 atm.

2007-09-24 09:30:01 · 1 answers · asked by Tiffany 4

We did an experiment with magnesium verifying the law of conservation of mass. we weighed the crucible, then the crucible and the magnesium together, then a final time after heating the magnesium. We had to answer questions at the end and this one has me stumped. She asks:

If the formation of magnesium nitride is not taken into account and the gray residue after the initial heating is assumed to be wholly magnesium oxide, the experiment would take much less time. Explain what errors might result, i.e., would the mass of the MgO/ Mg3N2 residue be greater or less than the mass of pure MgO residue? How would this affect the final percentage yield?

my thoughts on this is that the residue would actually be less than the mass of pure MgO residue. the reasoning behind that is the weight of the MgO compared to the weight of the Mg3N2. if i had .5g of MgO residue it would be .0124mol. Compared to if i had 1/2 MgO and Mg3N2 i would have .00867mol of combined. what do you guys think?

2007-09-24 09:05:02 · 1 answers · asked by john s 3

2007-09-24 08:58:34 · 2 answers · asked by flower 1

I bought a 150 dollar TI-89 for calculus and over the summer the batteries leaked. I took them out and removed as much of the acid as possible with paper towels. Is there anything I can do to remove the majority of acid? The calculator is not working because the acid is still on the current connectors.

Thanks

2007-09-24 08:55:42 · 4 answers · asked by James D 1

why can't you put your hand through a solid?

2007-09-24 08:50:41 · 4 answers · asked by London92 1

The element with an electronic configuration of:
(1s)2 (2s)2 (2p)5 would be?

Boron, Carbon, Nitogen, Oxygen, Fluorine?

2007-09-24 08:44:09 · 2 answers · asked by Moose 2

Can someone please explain how to do this question. I cannot remember how to do this for 2 unknown percents.

An element consists of two isotopes of mass 6.2882 and 7.9032 amu. If the average atomic mass of the element is 7.432 amu, calculate the percent abundance of the first isotope.

2007-09-24 08:40:48 · 1 answers · asked by AlfredoFernandez 2

please explain to me thanks

2007-09-24 08:40:29 · 1 answers · asked by Anonymous

I need to know the most common element on earth, including water. I believe it's hydrogen, but can someone tell me what it is, and give me a link that proves it? first to do so gets best answer

2007-09-24 08:29:31 · 10 answers · asked by Anonymous

Ok, I don't know were to start. Help please!!!

DG° = -210.155 kJ for the reaction 1A + 2B ==> 1C + 2D. What is DG (in kJ) for this reaction for the concentrations listed below? Assume 25.00°C.

Concentrations (mol/L)given:

A is 4.447
B is 2.281
C is 2.581
D is 4.196

Please Help Me!!!!!!!!!

2007-09-24 08:23:00 · 3 answers · asked by Nickname 1

Give the name and formula of the acids corresponding to each of the following oxoanions
1. hyponitrite ion, N2O22-
2. sulfate ion, SO42-
3. arsenate ion, AsO43-
4. dichromate ion, Cr2O72-

2007-09-24 08:19:39 · 2 answers · asked by brettmhannan 1

2007-09-24 08:13:08 · 2 answers · asked by tessy5343 1

2007-09-24 07:47:46 · 5 answers · asked by Anonymous

2007-09-24 07:43:35 · 4 answers · asked by Flor H 1