Chemistry - October 2007

in 10 litres of solution?

2007-10-07 13:17:40 · 4 answers · asked by Anonymous

I have an equation of FeS2 + O2 = Fe2O3 + SO4. What is the minimum number of moles of O2 required to react with 0.500 mole of FeS2? I cannot get the equation setup to work through it. Anyone know how to set it up?

2007-10-07 13:14:10 · 1 answers · asked by Michelle L 2

How many fluorine atoms are in 4.0 moles of
fluorine molecules?
1. 6.6 x 10^24 atoms
2. 2.4 x 1024 atoms
3. 4.8 x 1024 atoms
4. 1.5 x 1023 atoms



How many oxygen atoms (not molecules) are present in 1.25 moles of SO2?

2007-10-07 12:35:23 · 1 answers · asked by Anonymous

Calculate the number of ethanol molecules
(CH3CH2OH) that would contain 164 grams
of carbon.

2007-10-07 12:18:38 · 1 answers · asked by Anonymous

i need to know the method, the environmental problems created, and the physical properties involved.

2007-10-07 12:11:25 · 3 answers · asked by laze-butt 3

How many moles of bromine are in 2.60 £ 102
grams of bromine?
1. 0.0152 mol
2. 0.308 mol
3. 10.5 mol
4. 3.25 mol
5. 2.29 mol
6. 48.6 mol
7. 79.9 mol

2007-10-07 11:48:59 · 4 answers · asked by macaleen00 1

How many mols NaOH to neutralize 1 mol KHP, Potassium hydrogen phthalate

2007-10-07 11:45:12 · 2 answers · asked by Theava 2

Chrominium Isotope data

Isotope---Percent abundance----Mass(amu)
Cr-50----4.35%----------------... 49.946
Cr-52----83.79%---------------... 51.941
Cr-53-----9.50%---------------... 52.941
Cr-54-----2.36%---------------... 53.939

2007-10-07 11:38:25 · 1 answers · asked by Anonymous

Is it the same as an atomic number? I'm confused

2007-10-07 11:38:15 · 5 answers · asked by Griffin M 2

Consider the reactions shown below.

5 Fe2+ + MnO4- + 8 H+ ---> 5 Fe3+ + Mn2+ + 4 H2O
5 NO2- + 2 MnO4- + 6 H+ ---> 2 Mn2+ + 5 NO3- + 3 H2O

a) What is the molarity of KMnO4(aq) if 25.55 mL KMnO4(aq) is required to titrate 14.00 mL of 0.2334 M FeSO4(aq)?

b) What is the molarity of KMnO4(aq) if a 552.4 mg sample of KNO2 requires 32.61 mL KMnO4(aq) for its titration?

2007-10-07 11:35:17 · 2 answers · asked by unknownanonymous999 2

A 2.00% NaOH solution by mass has a density of 1.054 g/mL. What is the minimum molarity of an HCl(aq) solution that can be used to titrate a 4.00 mL sample of the NaOH(aq) if the titration is to be accomplished without having to refill a 50.00 mL buret used in the titration?

2007-10-07 11:33:37 · 2 answers · asked by unknownanonymous999 2

a) Aluminum reacts with KOH and water forming potassium ions, [Al(OH04]- and hydrogen gas.

b) hydrogen ions from the acid react with the tetrahydroxoaluminate ions to precipitate aluminium hydroxide.

c) Aluminium hydroxide reacts with addition hydrogen ions and water to form [Al(H2O)6]3+.

d) Alum forms from the potassium ions, hydrated aluminium ions, sulfate ions and water.

Thank you.

2007-10-07 11:32:25 · 4 answers · asked by Anonymous

A 9.00 mL sample of an aqueous solution of H2O2 is treated with an excess of KI(aq). The liberated I2 requires 44.93 mL of 0.5022 M Na2S2O3 for its titration. Is the H2O2(aq) up to full strength (3% H2O2 by mass) as an antiseptic solution? Assume that the density of the H2O2(aq) is 1.01 g/mL.

H2O2(aq) + H+ (aq) + I -(aq) ---> H2O(l) + I2(s) (not balanced)

I2(s) + S2O32-(aq) ---> S4O62-(aq) + I - (aq) (not balanced)

2007-10-07 11:30:38 · 2 answers · asked by unknownanonymous999 2

Do you have to convert mL to g in this problem. If so, I know that you use D=M/V but not sure how that fits into the overall answer.

2007-10-07 11:27:13 · 1 answers · asked by Emerson 5

How do you calculate the frequency of light when you're given the wavelength but not the speed? I know the equation for frequency is speed divided by wavelength, so I don't see how to do it without the speed part :P

Any help earns my undying love, I'm getting desperate. :D

2007-10-07 10:59:37 · 4 answers · asked by Anonymous

2007-10-07 10:48:48 · 1 answers · asked by king of soccer 1

The heat energy required to melt 1.00 g of ice at 0°C is 333 J. If one ice cube has a mass of 57.0 g, and a tray contains 16 ice cubes, what quantity of energy is required to melt a tray of ice cubes to form liquid water at 0°C?

2007-10-07 10:39:51 · 2 answers · asked by beeboroachgoingon197 1

Can someone please tell me what the oxidations numbers are for the following?

Cl in CCl4 H in NH3
P in P2O5 Na in Na3PO4


for Cl I got ....4
for P I got ..... 5
for H I got.... 1
for Na I'm getting 3.667 but it's not possible for decimal so would it be +1 ??

Please help? I have 30 min for this question... it's now 5:30 pm here so please help.

2007-10-07 10:31:38 · 2 answers · asked by Student 1

A 6.00% NaOH solution by mass has a density of 1.054 g/mL. What is the minimum molarity of an HCl(aq) solution that can be used to titrate a 2.00 mL sample of the NaOH(aq) if the titration is to be accomplished without having to refill a 50.00 mL buret used in the titration?

2007-10-07 10:29:03 · 2 answers · asked by jap 1

I heard that a forensic science degree is bad if you plan on working as a forensic chemist and that I should get a chemistry degree instead? Is that true and why or why not? Thanks. If I end up getting a chemsitry degree what other options of work are available?

2007-10-07 10:00:53 · 6 answers · asked by amgtt_18 2

this is a side question to:
http://answers.yahoo.com/question/index;_ylt=AoOIrcTNh2O5KMiYAddkQ87sy6IX;_ylv=3?qid=20071007123550AA8VHBk

(anyone who answers that one PROPERLY gets 10 points from this too, seeing as they're related)

but how many valence electrons does chromium have?

2007-10-07 09:56:00 · 2 answers · asked by Z3DA 3

clogs in plumbing.

2007-10-07 08:03:46 · 1 answers · asked by Maria D 1

What is the definition of chromatography?

2007-10-07 08:02:49 · 2 answers · asked by ¿¿ANswER♠?? 3

A gas-filled weather balloon with a volume of 51.5 L is released at sea-level conditions of 755 torr and 23°C. The balloon can expand to a maximum volume of 760. L. When the balloon rises to an altitude at which the temperature is -5°C and the pressure is 0.059 atm, what will be the final volume of balloon?

2007-10-07 07:33:17 · 2 answers · asked by Anonymous

In the case of NaI and Pb(NO3)2, which forms a yellow precipitate, what effect will it have on the reaction if you pour NaI INTO Pb(NO3)2 instead of pouring Pb(NO3)2 INTO NaI?

2007-10-07 07:33:08 · 3 answers · asked by me 3

I don't understand hybridization really and i have to explain why nitrogen trifluoride and phosphoruos pentafluoride are stable molecules and how nitrogen pentafluoride does not exist.

Can someone explain how hybridization works by explaining them?

2007-10-07 07:29:48 · 1 answers · asked by senseless.student 1

2007-10-07 06:55:47 · 15 answers · asked by NICOLA P 1

1) what is 1mmol/l NADH in umol/ml and mgs/ml?
2) what is the importance of NADH metabolically? in quantitavtive analysis?
3) what is 0.005mmol/l Blue Dextran in mgs/ml? in nmol/l?
4) What is Blue Dextan used for in chromatography?
5)Broadly speaking, why is Hemoglobin a colored protein? why was this prepared in physiological salin(0.15mol/l NaCl) as diluent?
6) what is the molarity of a 2g/l glucose soln?
7) a winchester of commercial ammonia(NH3) specifies that it has 8.8g/l ammonia, how would you prepare 0.1 mol/l? what is this soln in mg/ml? umol/ml and %w/v?
8)what is the molecular mass of ethanol? how would you express 70%v/v ethanol in : mol/l, mmol/ml, %w/v and w/w?
[notes the speficifc gravity of ethanol is 0.789g/ml]
9)what is the molarity of a 0.1% w/w/ soln of cholesterol in ethanol? [Mol,mass of cholesterol=386Da]

i reli havnt got a clue here.
im so dead. brainy ppl pls help me!!

2007-10-07 06:52:30 · 3 answers · asked by Anonymous

I cant find the structure anywhere! some help would be apprieciated

2007-10-07 05:26:05 · 3 answers · asked by jujubeans 3

2007-10-07 05:25:10 · 1 answers · asked by Anonymous