Chemistry - November 2007

B. Calculate the volume of air at 25ºC and 1.00 atmosphere pressure that is needed to burn completely 15.0 grams of propane. Assume that oxygen has a density of 1.31 g/L at 25ºC and that air is 21.0% O2 by volume.

C. The heat of combustion of propane is –2,220 kJ/mol. Calculate the heat of formation, ΔHfº, of propane given that ΔHfº of H2O(l) = –285.3 kJ/mol and ΔHfº of CO2(g) = –393.5 kJ/mol.

D)Assume that all the heat given off in burning 20.0 grams of propane is transferred to a quantity of water (Cp = 4.184 J/g • K). The water increases in temperature from 18.0ºC to 37.0ºC. What volume (L) of water was heated

2007-11-27 12:06:55 · 1 answers · asked by BrunetteBeauty 2

How many sodium ions would create a stable compound with how many oxygen ions (look at their charges)? How would you then write the formula?

2007-11-27 12:04:44 · 1 answers · asked by Anonymous

Assume the temperature and pressure are the same. Explain your reasoning . Everyone disagrees on this but i don't know who is right!

2007-11-27 11:44:04 · 7 answers · asked by jeir35 2

Oxygen is often generated in the laboratory by the reaction between sodium peroxide (Na2O2) and water, under appropiate conidtions. Sodium hydroxide is the other product.

Just need help in writing the chemical equation, the rest of the equation in finding grams, volume and etc. I can do! Thank you so much for your help!

2007-11-27 11:35:42 · 2 answers · asked by Herschel 1

curiousityyy

2007-11-27 11:17:03 · 4 answers · asked by Christie 1

"Find the mass of exactly 1u in grams. Use Factor label method corresct sig figs and show all work"

I found out that 1u = 1/12 the mass of Carbon -12. So, 1/12th of 12 is 1. So the mass of 1u in grams is simply one. right?

But if I am right? then the problem has been answered, so why should I use the factor label method and sig figs? Did I mis something? Please explain.

2007-11-27 11:06:28 · 1 answers · asked by Anonymous

If anyone can help with this problem, your response is greatly appreciated. Thanks!!

An ice cube tray holds 355 g water. If the water initially has a temperature of 31°C, how many kilojoules of heat must be removed to cool and freeze the water at 0°C?

2007-11-27 11:05:47 · 2 answers · asked by Shay W 1

20.00 mL of 1.364-M HNO3 solution and 100.00 mL of 0.102-M HNO3 solution are combined and then diluted with water until the total volume is 250.00 mL.
What is the molarity of this HNO3 solution?

2007-11-27 10:58:12 · 1 answers · asked by browneyes70199 1

It'd be really helpful. Thanks!

2007-11-27 10:45:11 · 6 answers · asked by milkandcandies 2

Gallium, used primarily in semiconductors and light emitting diodes (LED's), is a soft, silver-colored metal.

2007-11-27 10:00:37 · 4 answers · asked by chica magneta 1

2007-11-27 09:06:24 · 3 answers · asked by Ana 2

help?

2007-11-27 09:01:38 · 2 answers · asked by ABC 2

Give me details like a certain smell?
Burnt wood?
Something rotten?

2007-11-27 08:41:46 · 17 answers · asked by lostboy83c 1

2007-11-27 06:14:56 · 4 answers · asked by Anonymous

2007-11-27 06:12:58 · 3 answers · asked by Anonymous

Why is it that my honey starts to freeze up with crystals. Then I microwave it and it flows like water. But when it cools down, it is a virtual solid with far more crystals than before?

2007-11-27 05:46:34 · 3 answers · asked by Frst Grade Rocks! Ω 7

2007-11-27 05:42:12 · 3 answers · asked by sf49erz21 2

would the temperature be colder, warmer, the same, or is there no correlation?

2007-11-27 04:56:06 · 2 answers · asked by Ana 2

Fluorine is produced chiefly from fluorite, CaF2. Fluorine can also be obtained as a by-product of the production of phosphate fertilizers, derived from phosphate rock [ 3 Ca3 (PO4)2 . CaF2] . What is the maximum mass of fluorine that could be extracted as a by-product from 1200 of phosphate rock?

2007-11-27 02:16:16 · 2 answers · asked by mceb 1

Okay so I have tried to answer this problem, but I am obviouslly not getting the correct answer.

Suppose a 28.1-mL sample of helium gas at 25 °C and 1.29 atm is heated to 90. °C and compressed to a volume of 15.2 mL. What will be the pressure of the sample?

V1=28.1 ml or .0281L
P1= 1.68 atm
T1= 298K
n1=1.930 mol

V2= 15.2 mL or .0152L
P2= ?
T2= 298K
N2= 1.930 mol

P2=P1XV1/V2

which is 1.29X.0281L/.0152L
= 2.38480 atm

Can someone let me know if I am doing something wrong. I would greatly appreciate it.

2007-11-27 01:33:42 · 3 answers · asked by chemgirl78 2

2007-11-27 00:37:11 · 4 answers · asked by Peggy W 1

70.
a. magnesium sulfide
b. nitrogen gas
c. barium hydroxide
d. copper (II) nitride
e. sulfide ion
f. calcium carbonate
g. sodium bromide
h. ferric sulfate

2007-11-26 23:47:49 · 5 answers · asked by Anonymous

i have a question about acid buffers: acid buffers r usually mixtures of weak acid and a salt of that acid. here we have solutions from HCL and sodium ethanoate, EXPLAIN how this mixture IS a buffer.
thanks :)

2007-11-26 23:36:24 · 3 answers · asked by leyla 3

Whats the function of chiral compounds in medicine?

2007-11-26 23:24:13 · 2 answers · asked by Vanilla`Goddess^_^ 1

what are the diff. between HG lamps & sodium lamps ? what are the advantages of sodium lamp over HG lamp. pl. thanks in advance.

2007-11-26 23:06:49 · 1 answers · asked by amshaikh748 1

In my English story someone discovers a chemical that can produce electricity more effectively than any other chemical discovered without giving off pollution.

I need a method in which a chemical could produce electricity as/more effectively as any other method of producing electricity.

Can anyone with a better knowledge than me of creating electricity think of a way in which this would work?

This chemical can have any qualities (be magnetic, acidic- ect).

2007-11-26 23:03:49 · 4 answers · asked by Kuy setimram 2

I also have to discuss covalent and ionic bonding in 1500 words...It's over 20 years since I did chemistry at school and what does science have to do with equine business which is what i'm studying...Does anyone have any useful advice PLEASE

2007-11-26 22:14:10 · 3 answers · asked by . 6

If Not..What Is It In??(Like Can I Buy It From The Store??)

2007-11-26 20:57:36 · 5 answers · asked by The Don 1

Galvanizing, a process used to prevent corrosion, involves coating iron metal with a thin layer of zinc metal

1) Iron nails can be galvanized using an electrolytic process. The nails to be galvanized would be attached to the

A- anode
B- electrode at which anions react
C- electrode at which oxidation occurs
D- electrode at which reduction occurs

2) A galvanized nail was placed in copper(ll) sulphate solution. After a day, the blue color of the solution disappeared and copper metal was produced. The procedure was repeated with objects made of other metals. Similar results would not be predicted for

A-an uncoated iron nail
B-a chromium plated spoon
C-a nickel plated coin
D-a gold plated bracelet

Im not sure the answers for these 2 questions..

2007-11-26 19:44:52 · 2 answers · asked by Anonymous

1) a solution is made by mixing 5.00mL 0.00300 M Fe(NO3)3 with 4.00 mL 0.00300 M KSCN and 3.00mL 1.0 M HNO3. After equilibrium is established, the concentration of Fe(SCN)+2 was determined to be 2.72 x 10^-4 M. Calculate the equilibrium constant for this reaction.

Fe+3(aq) + SCN-(aq) <--> Fe(SCN)+2(aq)


2) consider the equilibrium: A + 2B <--> 3C

at a certain temperature, 2.00 moles of A and 2.00 moles of B are placed in a 3.0-liter container. After equilibrium is established, the concentration of A is 0.5 mol/L. What is the value of the equilibrium constant, K?


does anyone know what to do?
thankyou!

2007-11-26 18:26:51 · 1 answers · asked by Anonymous