Chemistry - June 2007

or can it be atomic number, mass number, or valences?

2007-06-13 15:04:44 · 3 answers · asked by maxfashun911 1

stay frozen why?

2007-06-13 15:03:21 · 4 answers · asked by chatojmnz 1

In lab today, we separated a mixture of ammonium chloride, salt, and sand by heating the mixture, subliming the ammonium chloride, then adding water to the sand and salt and decanting to remove the salt from the sand, and finally heating the sand to remove the water. Could the separation have been done in the opposite order? For example, adding the water first and extracting the insoluable residue and then heating both separately? Why or why not? I'm just starting Chem and this one has me stumped. Thanks!

2007-06-13 14:58:33 · 1 answers · asked by greensock 5

approximately 6.0 calories per mole-degree C. Knowing that the specific heat capacity of three metals in Joules per gram-degree C. is 0.45 for Fe, 0.24 for Ag, and 0.13 for Au. Do these metals agree with the Law of DuLong and Petit? How do you know this? Using your understanding of bonding in metals, explain why this law appears to hold.

2007-06-13 14:54:03 · 2 answers · asked by Anonymous

EX. Mg + Cu(NO3)2 => ___ +____

Zn + HCl => ___ +_____

2007-06-13 13:20:49 · 2 answers · asked by Anonymous

5.5 degrees C. Benzene's density is 0.88 gm/ml, its heat of vaporization is 20.0 KJoules per mole, its heat of fusion is 10.0 KJoules per mole, its heat capacity is 0.50 KJoules per mole-degree C for liquid benzene, 0.25 KJoules per mole-degree C for solid benzene, and 0.125 KJoules per mole-degree C for gaseous benzene. Calculate the following:
A. The energy required to heat 390. grams of benzene from 300 degrees C to 600 degrees C.
B. The energy required to cool 3.90 micrograms of benzene from 60 degrees C to 20 degrees C.
C. The energy removed to heat 39.0 kilograms of benzene from -100 degrees C to -50 degrees C.
D. The volume occupied by 1 kilomole of liquid benzene at 25 degrees C and the volume occupied by 1 nanomole of benzene as a vapor at STP (assume an ideal gas)

2007-06-13 13:19:54 · 1 answers · asked by Anonymous

When heated, sodium metal combines with chlorine gas to form solid sodium chloride:

2NA + Cl2 --> 2NaCl

If 8.30 g of sodium is heated with an excess of chlorine, a total of 19.5 g of sodium chloride is produced. Determine the theoretical yield and percentage yield.

I missed the lesson at school, so im really confused. Can anyone help me please? Thanks.

2007-06-13 13:13:47 · 2 answers · asked by Anonymous

2007-06-13 12:16:31 · 11 answers · asked by Anonymous

2007-06-13 11:31:35 · 6 answers · asked by kristen m 1

The question is: A solution of HBr contains 2 g of HBr per litre and has a pH of 2.5. What is the Ka and the PoH?

My chem teacher never taught us this and the exam is in 2 day. How do u find the Ka???

2007-06-13 11:23:43 · 3 answers · asked by hahahalover 1

cyanic acid is a weak monoprotic acid if the intial concentration of cyanic acid is 0.150 M and the equilibrium concentration of H^3O+ is 4.8 x 10^-2 M, calculate ka for cyanic acid

isobutylamine is a weak base if the initall concentration of isobutylamine is 0.055 M and the equilibrium concentration of OH- is 4.0 x10^-3 M. calculate kb for isobutylamine

Gallic acid is a weak monoprotic acid If the initial concentration of gallic acid is 0.280 M and the equilibrium concentration of H^3O+ is 3.3 x 10^-3 M, calculate ka for galic acid

Trimethylamine is a weak base If the initial concentration of trimethylamine is 0.390 M and the equilibrium concentration of OH- is 4.4 x 10^-3 M. calculate kb for trimethylamine

Dripropylamine is a weak base if the intial concentration of dipropylamine is 0.160 M and the equilibrium concentration of OH- is 0.012 M, calculate Kb for dipropylamine

2007-06-13 10:30:22 · 3 answers · asked by Anonymous

NH^3(aq) + H^20(aq) >> NH^4+(aq) +OH-(aq)?

HNO^2(aq) + H^20(l) >>H^3O+(aq) + NO^2-(aq)?

HCN(aq) + H^2O(l) >> H^3O+(aq) + CN-(aq)?

2007-06-13 10:06:06 · 3 answers · asked by Anonymous

As I understand it, an asphyxiant displaces oxygen in your lungs and leads to suffocation. What I don't understand is, how isn't any gas besides oxygen considered an asphyxiant? Anything can displace oxygen and lead to suffocation, because you can breathe too much of it instead of getting oxygen.

2007-06-13 10:04:10 · 2 answers · asked by Anthony R 2

2007-06-13 09:59:10 · 2 answers · asked by lom borz 1

answer fast.. i have 2 submit it..

2007-06-13 09:45:35 · 2 answers · asked by Anonymous

1. 1-hexanol 2. isohexyl alcohol 3. 2-hexanol 4. 2-methyl-2-pentanol

2007-06-13 09:27:05 · 2 answers · asked by Anonymous

Why would one support funding over the other?

2007-06-13 09:03:20 · 2 answers · asked by chemicalcajun 4

Procedure:
1.put on goggles
2.use the balance to measure out 131g of sucrose
3.Place the sucrose in one 100-mL beaker. Add water to make 100 mL of solution. Stir until the sucrose dissolves,
4.Use the balance to measure out 31g of sodium chloride.
5.Place sodium chlloride in he other 100-mL beaker. Add water to make 100 mL of solution. stir until disolved
6. Add a pinch of additional sucrosee to the solution and stir. Continue adding until the solution unil it no longer dissolves.
7. Repeat step 6 for the sodium chloride solution, adding pinches of sodium chloride until the no longer dissolve

THE QUESTIONS!

1. what was the concentration of the solutioin containing 131g of sucrose? what wass the concentration of the solution containing 31 g of sodium chloride? which of the two solutes could dissolve at a higher concentration?
2. can you think of a difference between these two solids that mightacount for their differing solubilities?
3. which would dissolve better, dextrose,sugar,salt?

2007-06-13 08:47:26 · 2 answers · asked by Anonymous

How can I identify a di-pole di-pole force?
How can I identify a polar or non-polar or covalent bond?
What does the "smallest or largest radius" mean? (not in a circle for math)

2007-06-13 08:14:39 · 4 answers · asked by Chris F 1

slightly. This __________ multiplied by _______ equals the nuclear binding energy of arbon 12.

A: mass defect, the atom's mass.
B: mass difference, mc^2
C: mass defect, mc^2
D: mass difference, the atom's mass

If you pass radiation between two charged plates, which two kinds of radiation emissions willbe attracked and bent toward a negative plate?

A: Positrons and alpha particles
B: Beta particles and gamma rays
C: Gamma rays and positrons
D: Alpha particles and Beta particles

I have done all my homework myself, I am just stuck with these 2 questions, so please no answers telling me to do it myself

2007-06-13 08:07:56 · 4 answers · asked by Mmm 1

A mixture of 10cm^3 of methane and 10cm^3 of ethane was sparked with an excess of oxygen. After cooling to room temperature, the reidual gas was passed through pottasium hydroxide.

what volume of gas was absorbed by the alkali?
A)15cm^3
B)20cm^3
C)30cm^3
D)40cm^3

2007-06-13 08:03:47 · 3 answers · asked by Anonymous

people have been trying to heelp me but i still dont understand...

write the net ionic equation corresponding to the precipitation reaction that occurs.

a) Na+(aq) + Cl-(aq) + Ag+(aq) + NO^3-(aq) - AgCl (s) + Na+ (aq) + NO^3- (aq)

b) 2 NH^4+(aq) + CO^3^2-(aq) + Ca^2+(aq) + 2 CI-(aq) - CaCO^3 (s) + 2NH^4+(aq) + 2CI- (aq)

c) Pb^2 (aq) + 2 NO^3- (aq) + 2 H+(aq) + 2 Br- (aq) - PbBr^2 (s) + 2 NO^3- (aq) + 2 H+(aq)

d) Fe^2+ (aq) + 2 CI- (aq) + 2K+(aq) + S^2- (aq) - FS (s) + 2 CI- (aq) + 2 K+(aq)

2007-06-13 07:51:03 · 4 answers · asked by Ashley T 1

and why is it in toothpast,soap,? I heard its not good for your body is there other products out there.

2007-06-13 07:46:35 · 2 answers · asked by KAT 3

For example, say you have a constantly heated piece of metal at say 400 deg F. If you pour water on it from time to time, won't it just evaporate, or will it potentially cause rust damage?

2007-06-13 07:41:36 · 3 answers · asked by Chris A 1

could someone please check my work? Thank you. Note(some of these reactions may be reversible but I'm not sure if I have them right)

1. carbon dioxide gas is bubbled through a solution of lithium hydroxide.
CO2(g)+2LiOH(aq) ===> Li2CO3(aq)+ HOH(l)

2. Sodium nitrite is reacted with hydrochloric acid
NaNo2(aq)+HCl(aq) ===>NaCl(aq)+HNO2(aq)
(not reveresible, I think? right?)

3. carbon dioxide gas is reacted with solid potassium oxide
CO2(g)+K2O(s)===>K2CO3(?)

4. ammonium carbonate+potassium bromide
(NH4)2CO3(aq)+KBr(aq) <====> NH4Br(aq)+ K2CO3(aq)
(this should be reversible right?)

5. oxalic acid(.1M)reacts with an equal volume of cesium hydroxide(.1M)
H2C2O4(aq)+CsOH(aq)===>CsHC2O4(aq)+HOH(l)
(I read this one somewhere and think this is right but why is molarity important)

thank you for your help

2007-06-13 07:22:39 · 1 answers · asked by Anonymous

Examples?

2007-06-13 07:11:59 · 2 answers · asked by toughluck1089 2

Is ethane reduced to ethanol or oxidized to ethanol?
Is O a reducing agent or oxidizing agent?

2007-06-13 07:04:59 · 1 answers · asked by Josh 2

According to me atomic mass is number of neutron+number of proton of an atom.it means that atomic mass should be in simple whole number.
But in perodic table for some elements it is given in decimal why?

2007-06-13 07:03:20 · 4 answers · asked by Anonymous

can anyone help please

2007-06-13 06:50:55 · 4 answers · asked by Anonymous

Which of these acid-base (neutralisation) reactions could be titrated using burette and flask to give a sharp end point?
A) sulphuric acid and alluminium oxide
B) sulphuric acid and magnesium hydroxide
C) sulphuric acid and magnesium oxide
D) sulphuric acid and sodium hydroxide

i know the answer is D, but i dont understand exactly why..and what is meant by shap end point?

2) Which compounds may result from mixing ethane and chlorine in the prescence of sunlight (the answer could be one of the below, two or even all)

A) CH3CH2Cl
B) CH3CH2CH2CH3
C) CH3CHClCHClCH3

I can understand how A and B are formed, but dont understand how C is formed.


3)Which compound has a boiling point which is influenced by hydrogen bonding? (only one answer)
A) CH3CHO
B) CH3OCH3
C) HCOOH
D) HCOOCH3

Arent all of them affected by hydrogen bonding?

Thanx for the help

2007-06-13 06:45:36 · 2 answers · asked by Anonymous