Chemistry - October 2006

Calculate the standard enthalpy of formation for diamond, given that
C(graphite) + O2(g) → CO2(g) ΔH0 = –393.5 kJ/mol
C(diamond) + O2(g) → CO2(g) ΔH0 = –395.4 kJ/mol

Is it 1.9 or -1.9 and why?

2006-10-31 13:27:00 · 3 answers · asked by hmmm 2

Project Tommorow and I need to know if Germanium the element is flammabel and its solubility.

2006-10-31 13:25:17 · 4 answers · asked by S 2

I've one chemistry problem . If u don't know then wright i don't know i'll get to know that how many people have the courage to solve this simple question. My question is:-
500centimetre cube of a given soln s contains 9.0 gram of glucose(C6H12O6). What is the molality of the soln.?
Formula for molality is :-
Molality = mass of solute
__________________________________________
( gram molecular mass of solute).(mass of solvent)
Molecular mass of glucose is 180.

2006-10-31 13:25:05 · 3 answers · asked by Black Eyes 2

a. NaI
b. K2SO4
c. NaCN
d. Ba(OH)2
e. (NH4)2SO4

2006-10-31 13:15:03 · 2 answers · asked by Catherine D 1

Suppose you have a solution that might contain any or all of the following cations:Cu2+, Ag+, Ba2+, and Mn2+. Addition of HCl causes a precipitate to form. After the precipitate is filtered off , and a solution of NaOH is added to the supernatant liquid until it is strongly alkaline. No precipitate is formed. Which ions are present in each of the precipitates? Which cations are not present in the original solution?

2006-10-31 12:59:59 · 2 answers · asked by Catherine D 1

How much heat is released to the surroundings when 4.07 g of aluminum reacts with excess iron(III) oxide to give aluminum oxide and metallic iron? (The heats of formation of iron(III) oxide and aluminum oxide are -822 kJ/mol and -1670. kJ/mol, respectively.)

I think this is 64kj but why do you have to devide 128 by 2 to get 64? why isnt the answer just 128?

2006-10-31 12:48:47 · 1 answers · asked by hmmm 2

can yall please help me out?!

2006-10-31 12:47:42 · 7 answers · asked by andrea m 2

2006-10-31 12:41:42 · 3 answers · asked by Christine B 1

2006-10-31 12:40:20 · 2 answers · asked by Simey F Baby 1

Predict the signs of spontaneous change for each of the following processes. (+ or -)?

a.) A piece of wax melting
b.) silver chloride precipitating from a solution
c.) Dew forming
d.) gasoline vapors mixing with air in a car engine
e.) hot air expanding
f.) breath condensing in cold air

2006-10-31 12:33:25 · 3 answers · asked by softball579 1

2006-10-31 12:29:18 · 9 answers · asked by Just 2

This will be on my test tommorrow and i want to know what the answer is. can someone help me figure it out?

2006-10-31 12:28:13 · 2 answers · asked by Ballerina 1

2006-10-31 12:27:44 · 7 answers · asked by Just 2

k we talked about it i class today but i didnt get it

1. sodium+aluminum chloride- sodium chloride&aluminum

2. patasum bromide+ chlorine- patasum chloride&bromine

3. hydrogen peroxide - water & oxygen

k if u could help thatxs sooooooooooo much

2006-10-31 12:23:51 · 4 answers · asked by degrassi_27 2

...would they have it at a pharamacy?

2006-10-31 12:22:15 · 3 answers · asked by Brian M 1

2006-10-31 12:05:07 · 3 answers · asked by Larson D 1

cyclohexandiol. Would you expect these compounds to be separable by TLC? Why
or why not?

2006-10-31 11:54:48 · 2 answers · asked by bbydiva 1

2006-10-31 11:52:56 · 1 answers · asked by substance 2

Im doing this project:
http://www.physics.rutgers.edu/~croft/cancrsh.htm
http://demoroom.physics.ncsu.edu/html/demos/283.html

Will placing the can on the bunsen burner to boil the water, melt the can?

2006-10-31 11:49:59 · 5 answers · asked by R B 3

2006-10-31 11:36:38 · 3 answers · asked by ☺Inquisitive 1☺ 3

Q.) In a future hydrogen-fuel economy, the cheapest source of H2 will certainly be water. it takes 467kJ to produce 1 mol of H atoms from water. what is the frequency, wavelength, and minimum energy of a photon that can free an H atom from water?

V=E/h-->> { (467kJ)(10^3J/1KJ) (mol/6.022x10^23) / (6.626x10^-34) }
E=7.75x10^-19
V=1.17x10^15

Lamda=hc/E-->> { (6.626x10^-34J) (3.00x10^8) / (7.75x10^-19) }
Lamda=2.56x10^-7

So is this right?

2006-10-31 11:31:18 · 3 answers · asked by Anonymous

2006-10-31 11:29:09 · 2 answers · asked by substance 2

Compare and contrast atoms and molecules. Y their similer amd different. please help

2006-10-31 11:22:36 · 8 answers · asked by crashanator11 1

2006-10-31 11:19:11 · 4 answers · asked by Anonymous

Up until now I have been given the "fairytale" version of chemistry. My teacher told me that atoms "want" to have a complete outer shell. I'm sure that doing so brings the total energy lower but I don't understand how. Any and all input would be appreciated.

2006-10-31 11:03:53 · 2 answers · asked by Chris G 2

2006-10-31 11:02:10 · 4 answers · asked by bobby j hampton :D 1

How many moles of ammonium chloride must be added to 1.0 L of 0.50 M ammonia to prepare the buffer?

a. 0.40 mol
b. 0.80 mol
c. 1.2 mol
d. 2.5 mol
e. 4.5 mol

2006-10-31 10:58:57 · 1 answers · asked by Anonymous

a. 11.82
b. 10.04
c. 3.44
d. 2.18
e. 0.80

2006-10-31 10:57:44 · 2 answers · asked by Anonymous

For NH3, Kb = 1.8 x 10-5

a. 3.81
b. 4.74
c. 7.92
d. 9.25
e. 10.19

2006-10-31 10:57:04 · 1 answers · asked by Anonymous

2006-10-31 10:52:06 · 3 answers · asked by -- 2