Chemistry - October 2007

needed for the balanced half-equation?

2007-10-27 13:56:30 · 2 answers · asked by Anonymous

I am doing a project on and element and i have chosen potassium. I am having trouble finding the following two things about it: Economic issues related to the element and environmental impacts of the element. If anyone knows where i can find this please let me know this would be very helpful...i've looked everywhere thanks!

2007-10-27 13:42:06 · 1 answers · asked by Anonymous

http://img103.imageshack.us/img103/9302/spdistus8.jpg

Based on the distributions show above, which of the following are true statements for the three gases I II and III ?
Note that the temperature is constant

a) gas III is the lightest of the three gases

b) the most probable speed of the molecules of gas II
is greater than that of the molecules of gas III

c) all the molecules of gas III have an actual speed that is greater
than those of gas I

d) plots of the molecular kinetic energy distribution for the three gases
would all be identical (superimposed on each other)

e) increasing the temperature would increase the most probable speed
of the molecules of each gas

2007-10-27 12:57:22 · 1 answers · asked by mike m 1

2007-10-27 12:35:40 · 1 answers · asked by Nia A 1

The combustion of 0.1571 g benzoic acid increases the temperature of a bomb calorimeter by 2.67°C. Calculate the heat capacity of this calorimeter. (The energy released by combustion of benzoic acid is 26.42 kJ/g.)

a. A 0.2170 g sample of vanillin (C8H8O3) is then burned in the same calorimeter, and the temperature increases by 3.29°C. What is the energy of combustion per gram of vanillin?


b. What is the energy of combustion per mole of vanillin?

2007-10-27 11:43:22 · 1 answers · asked by Anonymous

A balloon filled with 31.9 mol helium has a volume of 715. L at 0.0°C and 1.00 atm pressure. The temperature of the balloon is increased to 68.0°C as it expands to a volume of 893. L, the pressure remaining constant. Calculate q, w, and E for the helium in the balloon. (The molar heat capacity for helium gas is 20.8 J/°C·mol.)

2007-10-27 11:42:45 · 1 answers · asked by Anonymous

Yes, I'm not a chemist... but I do like chemistry. I'd like it even more if it wasn't so intricate with so many unnecessary distinctions to make between stuff! But anyway, I'm doing a chemical reactions unit and it's not THAT bad, there's single displacement, double displacement, synthesis and decomposition... I just got lost when we brought in combustion and sorta got neutralization. I have some chem. problems here, can anyone explain them to me? I know the rxns but I just don't get combustion and whether they're aqeuous or not. Here:
1.) Acetic Acid + Sodium bicarbonate (baking soda) = ?
2.) Copper wire in flame makes...?
3.) Mg + lead II nitrate makes...?
4.) hydrochloric acid + sodium hydroxide= ?
5.) lead II nitrate + potassium iodide=?
6.) copper II sulfate + iron=?
7.) copper II sulfate pentahydroxide in flame makes...?!

Is hydrogen aqueous? Is iron? Is Mg? And when is it a gas or liquid? Can you balance the eqns. too plz?

Thanx for your help!

2007-10-27 10:27:27 · 3 answers · asked by mikita_daita 1

Okay so i have a science project. It is to do an experiment to show if " the more particles dissolved in the water, the higher the boiling point." is true or not. My question is how do i know WHEN to take the temperature of the water. If it when theres any sign of bubbles?

Thanks. ;]

2007-10-27 10:14:48 · 2 answers · asked by Anonymous

My daughter has to build an octohedral model for Chemistry class. She will use plastic, styrofoam and paint.

Has anyone every done this before and do you have any suggestions?

2007-10-27 10:07:42 · 2 answers · asked by Stareyes 5

2007-10-27 10:05:18 · 1 answers · asked by Anonymous

Can you mix it with water or not.

2007-10-27 10:02:15 · 1 answers · asked by John R 4

After adding more salt, and stirring it, you notice some salt is sitting on the bottom of the glass.

a) Is this salt-water combination a mixture, solution, suspension, or emulsion?

b) Explain why no more salt will dissolve in the water.

c) What could you do to this same glass of water to get more salt to dissolve?

d) If you put this glass of salt-water into the freezer, what would you expect to happen to it? (sorry, just saying it will freeze is not enough)

2007-10-27 09:56:25 · 1 answers · asked by tia 3

I need it for a science project, nd I do not fully understand the problem for the science project.

2007-10-27 09:50:29 · 1 answers · asked by John R 4

by looking at the structurual formula of a b vitamin, how would you be able to tell it is one. in other words what do all b vitamins have in common based on structual formula?

2007-10-27 09:50:09 · 1 answers · asked by ladygem 1

Also for 27.1g of ntrogen monoxide. The questions come from introduction to chemistry 2nd edition by nivaldo j tro. I know the answers are .945 and .903 moles, but I want to know how to set up the equation.

2007-10-27 09:39:57 · 3 answers · asked by Anonymous

Red phosphorus.

2007-10-27 09:35:10 · 1 answers · asked by blueanswers 2

2007-10-27 09:30:04 · 3 answers · asked by Easton M 2

Find an expression for the change in entropy when two blocks of the same substance and of equal mass, one at temperature Th and the other at Tc are brought into thermal contact and allowed to reach equilibrium. Evaluate the change for two blocks of copper, each of mass 500 g with heat capacity of 24.4 JK^-1, taking Th=500K and Tc=250K. Thank you very much for responds

2007-10-27 08:56:08 · 1 answers · asked by tchem 1

The combustion of 0.1571 g benzoic acid increases the temperature of a bomb calorimeter by 2.67°C. Calculate the heat capacity of this calorimeter. (The energy released by combustion of benzoic acid is 26.42 kJ/g.)?

A 0.2170 g sample of vanillin (C8H8O3) is then burned in the same calorimeter, and the temperature increases by 3.29°C. What is the energy of combustion per gram of vanillin?

2007-10-27 08:25:03 · 1 answers · asked by toocool 1

A 1.397 g sample of thymol, C10H14O(s) (a preservative and a mold and mildew preventative), is burned in a bomb calorimeter assembly. The temperature increase is 11.23°C, and the heat capacity of the bomb calorimeter is 4.68 kJ/°C. What is the heat of combustion of thymol, expressed in kilojoules per mole of C10H14O?

2007-10-27 08:21:21 · 1 answers · asked by toocool 1

Salicylic acid, C7H6O3, has been suggested as a calorimetric standard. Its heat of combustion is -3.023 103 kJ/mol C7H6O3. From the following data determine the heat capacity of a bomb calorimeter assembly (that is, the bomb, water, stirrer, thermometer, wires, and so forth).


mass of salicylic acid burned: 1.111 g
initial calorimeter temperature: 23.07°C
final calorimeter temperature: 29.55°C

2007-10-27 08:20:53 · 2 answers · asked by toocool 1

In a coffee-cup calorimeter, 1.20 g of NH4NO3 is mixed with 76.0 g of water at an initial temperature of 25.00°C. After dissolution of the salt, the final temperature of the calorimeter contents is 23.21°C. Assuming the solution has a heat capacity of 4.18 J/°C·g and assuming no heat loss to the calorimeter, calculate the enthalpy change for the dissolution of NH4NO3 in units of kJ/mol.

2007-10-27 08:20:25 · 1 answers · asked by toocool 1

is this an oil?

please can you provide me with as much information about glycerol triethanoate as possible. it would be much appreciated.

thank you

2007-10-27 07:49:02 · 1 answers · asked by Anonymous

In the laboratory, 5.17 g of Sr(NO3)2 is dissolved in enough water to form 0.650 L. A 0.100 L sample is withdrawn from this stock solution and titrated with a 0.0360 M solution of Na2CrO4. What volume of Na2CrO4 solution is needed to precipitate all the Sr2+(aq) as SrCrO4?

(in liters)

2007-10-27 07:46:06 · 1 answers · asked by JTOWN 2

If 54.8 mL of BaCl2 solution is needed to precipitate all the sulfate ion in a 544 mg sample of Na2SO4 (forming BaSO4), what is the molarity of the solution?

2007-10-27 07:43:29 · 1 answers · asked by JTOWN 2

2007-10-27 07:37:39 · 2 answers · asked by luvalwayz_divya 1

I know they are very similar but what is the difference?

2007-10-27 07:31:40 · 3 answers · asked by Anonymous

2007-10-27 07:30:34 · 4 answers · asked by ... 2

write the equation representing the second ionization of iron. Indicate the states of the species in the reaction (s), (l), (g), (aq).

2007-10-27 07:25:50 · 1 answers · asked by greenie23510 1

For the following endothermic reaction at equilibrium:

Fe2O3 (s) + 3 H2 (g) 2 Fe(s) + 3 H2O(g)

Decide (YES/NO) if each of the following changes will increase the value of K (T = temperature).


Add Ne(g) (constant T)

Add a catalyst (constant T)

Decrease the volume (constant T)

Add H2 (constant T)

Increase the T

Remove H2 (constant T)

Decrease the T

2007-10-27 07:16:13 · 2 answers · asked by Guinness 3