Chemistry - February 2007

2007-02-27 23:25:28 · 3 answers · asked by wei jun 1

Calculate the molar solubility of AgBr in pure water and in 0.12 F KBr. Explain the reason for the difference between these values.

i know the ksp for AgBr is 5.0 x 10^-11.
the answer is x = 4.2 x 10^-12

can someone teach me how come that's the answer.

2007-02-27 22:42:47 · 1 answers · asked by Rain 2

can someone explain this problem to me, my teacher did not get a chance to go over it.

At 698.6 K, a mixture of the three gases H2, I2, and HI is at equilibirum when PH2 = PI2 = 0.02745 atm and PHI = 0.2024 atm. If HI is added to the reaction vessel at constant tmeperature, so that PHI is suddenly increased to 0.8000 atm, what will the pressure of each of these gases be when the system returns to equilibrium?

thanks

2007-02-27 22:40:49 · 2 answers · asked by Rain 2

Can someone please help me with this? Im so bad at chemistry and I've tried and tried.

You have a quantity of solid potassium dichromate from which you are to make 100ml of 4mM solution. Calculate how much potassium dichromate you must weigh out for this solution (molecular mass of potassium dichromate = 294.18g/mole)

That's the first part of the question and I worked it out to be 1.176727g, from rearranging n=m/M to m=nxM and then 0.004 moles x 294.18 g/mole is 1.17672grams.

I think I'm right on that part but then the second part is actually weighing it out, and then making the 4mM solution. I weighed out 1.19 grams so how much 100 mM sodium phosphate buffer do i need to add to create the 4mM solution?. (Im guessing you use C1V1=C2V2 but I dont see how)

thanks for any help guys!!

2007-02-27 22:40:09 · 1 answers · asked by ashleigh b 1

2007-02-27 22:34:35 · 1 answers · asked by Anonymous

2007-02-27 22:32:06 · 1 answers · asked by Anonymous

2007-02-27 22:29:05 · 1 answers · asked by hiscageofstars 1

2007-02-27 22:04:07 · 1 answers · asked by srinivas v 1

2007-02-27 20:47:53 · 2 answers · asked by Anonymous

Plz tell me how far are the terms related?

2007-02-27 20:14:05 · 2 answers · asked by Ahmed S 1

2007-02-27 20:05:43 · 1 answers · asked by Rajchem 2

Question 1: Is steel a mixture or a compound?

Question 2: If an atom of an element has 69 neutrons and 50 electrons, it's mass number is:
a) 119
b) 69
c)50
d)19
e) none of these

Note: Mass number is the number of protons and neutrons. I thought the answer was a, 119 but then I realised wouldn't it depend what charge the atom was which would altar the electrons and protons (they may not be the same)? Is it e, none of these or a?

Question 3:
Is magnetising a screw driver a chemical and physcial change or only a physical change? What about kicking a football and also production of sound by the vocal cords?

Thankyou for helping.

2007-02-27 20:01:08 · 4 answers · asked by Anonymous

Automobile airbags are inflated by nitrogen gas, generated from the explosive decomposition of solid sodium azide:
2NaN3---->2Na + 3N2

What volume of N2 at 1°C and 0.96 atm pressure can be produced from the decomposition of 12.2 g of NaN3?


Umm..ya. How do I do this?

2007-02-27 18:48:03 · 3 answers · asked by ojndoanj 3

5.97 g of a gaseous compound, comprised of only the elements carbon and fluorine, is analyzed and found to contain 1.43 g of carbon.
A 285-mL sample of the gas has a mass of 1.27 g at STP.
Enter the molecular formula of the compound.

I have no clue to go about this problem. A little help with an explanation would be nice =D

2007-02-27 18:34:12 · 1 answers · asked by ojndoanj 3

2007-02-27 18:26:17 · 5 answers · asked by sky_blue 1

Sodium carbonate is a reagent that may used to sandardize acids in the same way that you have used KHP in this emperiment. In such a standardization it was found that a .0498-g sample of sodium carbonate requried 23.5mL of a sulfuric acid solution to reach the end point for the reaction. What is the molarity of the H2SO4?

2007-02-27 18:19:45 · 1 answers · asked by Daniel G 1

At 25°C, Kp = 5.3 105 atm-2 for the following reaction.

N2(g) + 3 H2(g) 2 NH3(g)
When a certain partial pressure of NH3(g) is put into an otherwise empty rigid vessel at 25°C, equilibrium is reached when 50.0% of the original ammonia has decomposed. What was the original partial pressure of ammonia before any decomposition occurred?

2007-02-27 17:14:29 · 1 answers · asked by trypanophobic34 2

1. the energy change of any system is equal to the energy gained by the system minus the world done by the system
2. enthalpy is a thermodynamic quantity, and the change in enthalpy equals the energy flow at constant volume

i had this on an exam today, i just dont understand the phrasing.

2007-02-27 17:07:54 · 1 answers · asked by Anonymous

a. CS2
b. Al2(CO3)3
c. LiNO3
"1 mole = 6.022 x 10^23 atoms, or molecules"

2007-02-27 16:16:44 · 2 answers · asked by honest abe 4

Two isotopes of copper are naturally occurring with ^63Cu at 69.09% (62.93 amu) and ^65Cu at 30.91% (64.93amu ). What is the atomic mass of copper?

2007-02-27 16:09:24 · 6 answers · asked by orange_crush_05 6

Sodium nitrate, potassium chloride, barium sulfate

2007-02-27 16:06:02 · 4 answers · asked by blue_eyed_dancer13 1

Example: A cup of water is left in the freezer overnight. The result is ice with bubbles in it. Are these bubbles from dissolved gases in the water, or does the water take in gas from the atmosphere as it freezes?

2007-02-27 16:05:04 · 2 answers · asked by Anonymous

Elemental Sulfur boils at 445°C. At this temperature and 1.00 atm pressure, the density of gaseous sulfur is 4.35g/l. Based on this information, does sulfur form a monatomic gas under these conditions? If not, determine that actual molecular formula of gaseous sulfur at 445°C and 1.00 Atm.

2007-02-27 15:54:12 · 2 answers · asked by Anonymous

Experiment of Conversion of ethyl alcohol to ethyl acetate to ethyl amide.

2007-02-27 15:49:59 · 1 answers · asked by Izzan 1

Most other things tend to compress as they reach their freezing point.

2007-02-27 15:42:37 · 3 answers · asked by Anonymous

2007-02-27 15:42:05 · 3 answers · asked by Victoria 2

2007-02-27 15:33:43 · 1 answers · asked by steve t 1

In his explanation of the photoelectric effect, Einstein reasoned that the absorbed photon must have the minimum energy required to dislodge an electron from the metal surface. This energy is called the "work function" of that metal. What is the longest wavelength, in nanometers (nm), of radiation that could cause the photoelectric effect in sodium, for which the work function is 4.41×10-19 J?

2007-02-27 15:16:45 · 1 answers · asked by socr8711 2

2007-02-27 15:13:08 · 1 answers · asked by Anonymous

A ground state H-atom absorbs a photon of wavelength 93.78 nm and its electron attains a higher energy level. The atom then emits two photons: one of wavelength 2625.9 nm to reach an intermediate level and a second to return to the ground state. What was the wavelength of the second photon emitted?

2007-02-27 15:12:21 · 1 answers · asked by socr8711 2