Chemistry - December 2007

Silicon, which is in group IV , why cannot form a giant molecular structure itself like carbon, but with oxygen to form quartz?

2007-12-15 02:54:14 · 3 answers · asked by Anonymous

I heard it's corn starch or sodium bicarbonate which is it?

2007-12-15 02:29:13 · 6 answers · asked by dyude 2

Using pH = - log[H+] where the H+ represents the Hydrogen ion concentration, show calculations and / or steps for solving the equation, if the H+ of grapes is represented by 0.85
Show all steps taken to find the ph balance of the grapes

2007-12-15 02:20:41 · 2 answers · asked by lilmamahoney 1

2007-12-15 00:50:45 · 2 answers · asked by Anonymous

Electrolysis of HCl (hydrochloric acid) with steel electrodes. What do the anode and cathod produce?

2007-12-14 23:46:55 · 3 answers · asked by Anonymous

2007-12-14 23:39:55 · 3 answers · asked by Anonymous

I have read that the longest word in the English language is 1,909 letters long and it refers to a distinct part of DNA.

2007-12-14 21:03:10 · 1 answers · asked by tianjin 1

Why the elements in Group I and II are always soft and less denser while others are hard and high denser? What structure cost this? They all are both held by metallic bond.Is that because of less electrons in electron sea, so the attractive between the sea and the cation become smaller?

Don't tell me Group I is less dense because they got less outermost shell electrons only.... I want to know WHY!

2007-12-14 20:04:07 · 2 answers · asked by Anonymous

calculate the amount of CO 2 that could be produced when
(i) 1 mole of carbon is burnt in air
(ii) 1 mole of carbon is burnt in 16 g of dihydrogen
(iii) 2 moles of carbon burnt in 16 g of dihydrogen

2007-12-14 19:31:54 · 1 answers · asked by Anonymous

Epsom salts that are used as a laxative consist of MgSO4 * 7H20. How many grams of Mg are present in 0.0250 mole of MgSO4 * 7H20, which is 9.86% Mg.

The answer I calculated is 0.297g Mg, but I'm not sure if it's correct. Thanks for your help!

2007-12-14 16:03:58 · 5 answers · asked by Steven M 3

Question 1 2 points Save
The temperature of a sample of an ideal gas confined in a 2.0 L container was raised from 27 oC to 77 oC. If the initial pressure of the gas was 1200 mmHg, what was the final pressure of the gas?
300 mmHg
600 mmHg
1400 mmHg
2400 mmHg
3600 mmHg
A sealed container contains 0.20 moles of oxygen gas and 0.10 moles of hydrogen gas. If the temperature is 25 oC throughout the container, which of the following is true?
The partial pressures of the two gases are the same.
The average kinetic energy of the two gases are the same.
The molecular masses of the two gases are the same.
The total masses of the two gases are the same.
The average molecular speeds of the two gases are the same.

2007-12-14 15:10:36 · 13 answers · asked by Anonymous

2007-12-14 14:58:40 · 7 answers · asked by ethereality 3

According to the VSEPR model, the arrangement of electron pairs around NH3 and CH4 are
A. Different b.c in each case there are a different number of atoms around the central atom
B. Different or the same, depending on the conditions leading to maximum repulsion.
C. the same because both nitrogen and carbon are both in the second period
D. different because in each case there are a different number of electron pairs around the central atom
E. the same because in each case there are the same number of electron pairs around the central atom

2007-12-14 14:31:45 · 7 answers · asked by bob 1

during my frequent travels, I notice that the toothpaste supplied in hotels are made in China with no identifiable brand name. A check with the hotel management reveal their ignorance on the matter (or are they trying to cover up?) Are there any assurance that these toothpaste do not contain the harmful DEG substance?
How to tell if a certain toothpaste contain DEG? Could the taste, color, texture or smell of the toothpaste provide any clues?

2007-12-14 11:30:52 · 4 answers · asked by Avex 3

plz and thnx you

2007-12-14 09:22:42 · 45 answers · asked by Nicky 2

I can't get the concept intended in my lesson for school.

Here it is:

1146 joules of heat is released when a 100.0 gram sample of an unknown metal cools from 95.00°C to 65.00°C. Determine the specific heat of a metal.

Please explain what you did, so I can get it!

Thank You in advance!

2007-12-14 08:25:31 · 6 answers · asked by A Firefighter 2

Which of the following substances would have the highest melting points?

BF ( F sub 3)
NaF
H (sub 2) O
HF

Which one of the following substances would likly be the best conductor of electricity in the pure liquid state?

Br (sub 2)
PCl (Cl sub 2)
BaF (F sub 2)
CH ( H sub 4)
H (sub 2) O

Thanks in advance!

2007-12-14 08:15:26 · 1 answers · asked by C-B 2

the mass of 1 litre of oxygen =1.4g how many litres of oxygen is given up at the combustion of 21g of magnesiumwhich has an equivalent of 0,5 mols.

2007-12-14 08:05:53 · 2 answers · asked by jammal hines 1

2007-12-14 07:44:57 · 20 answers · asked by ṡhαḋøώḋυṡτ ღ вιттєя ѕωєєт ღ 6

Would an upside down conical shaped vessel heat faster than a cylindrical one?

Taking into consideration that heat rises and that the water is being heat from the bottom of the vessel.

What do you think? Also, please state your reasons and source if possible.

2007-12-14 07:14:59 · 7 answers · asked by britishbuddha 2

1. In a molecule in which the central atom exhibits sp3d2 hybrid orbitals, the electron pairs are directed toward the corners of:

(A) a tetrahedron
(B) a square-based pyramid
(C) a trigonal bipyramid
(D) a square
(E) an octahedron

Someone told me that it was E) an octahedron but I don't understand why. Can someone else why it's an octahedron and not any of the others? I'm confused...thanks so much.

2007-12-14 06:12:57 · 4 answers · asked by Anonymous

Thanks.

2007-12-14 06:09:44 · 3 answers · asked by chemquestions1 1

2007-12-14 06:05:06 · 2 answers · asked by sam 1

2007-12-14 06:03:53 · 1 answers · asked by sam 1

For a certain crystal X-ray diffraction showed the distance between the layer of atoms was 230 pm. If the crytal was held at an angle of 20.0o to the beam. What was the wavelength of the X-ray radiation in nm ?

2007-12-14 05:59:50 · 1 answers · asked by Liv 2

upper left
lower left
lower right
upper right

2007-12-14 05:34:51 · 5 answers · asked by Anonymous

When 0.560 g of Na(s) reacts with excess F2(g) to form NaF(s), 13.8 kJ of heat is evolved at standard-state conditions. What is the standard enthalpy of formation (H°f) of NaF(s)?

Na(s) + F2(g)  NaF(s) (H°f) ??

A. 24.8 kJ/mol B. 570 kJ/mol C. 24.8 kJ/mol D. -570 kJ/mol

2007-12-14 05:32:31 · 1 answers · asked by Qatarya 1

Hi, i'm having troubles starting with the following chem question:
Balc'd. equation: 4Au(s) + 8CN-(aq) + O2(g) + 2H2O (l) -> 4[Au(CN)2]-(aq) + 4OH-(aq)
How many liters of 0.22M NaCN solution would be needed to extract the gold from 1000kg of rock, if the rock is 0.063% gold by mass?

Any tips/suggestions would be great :)

2007-12-14 05:30:22 · 2 answers · asked by tomek 1

A radium watch dial contained 20 micrograms of radium-226 in the year 2000. The watch was discovered by archeologists in the future and found to contain only 5 micrograms of radium-226. In about what future year was the watch discovered?

2007-12-14 05:29:44 · 2 answers · asked by Anonymous

what is ture about the molar mass of chlorine gas?


A. the molar mass is 35.5 g
B. the molar mass is 71.0 g
C. the molar mass is equal to the mass of one mole of chlorine atoms
D. none of the above

2007-12-14 05:29:26 · 3 answers · asked by Anonymous