Chemistry - March 2007

A pure sample of iron (III) sulfide, Fe2S3, has a mass of 8.160g
a) How many moles of Fe2S3 are in the sample?

b) What number of moles of iron (III) ions are present?

c) What number of moles of sulfide ions are present?

d) What maximum mass of iron could be obtained from the sample?

Please help me! I have been working on these questions for about 2 and a half hours. I have been going through my chemistry textbook and booklets. I think I have the answer to a but I have no idea how to find the number of moles of iron (III) ions. I need to know that to answer c. In part d, how do I find the answer? Please help me and show me the correct processes (clear working) involved before the answers. Thankyou chemistry wizzes.

2007-03-13 18:04:44 · 3 answers · asked by Anonymous

PO2^3
N2O2^2
AsO2
K2CrO4
Ca3(PO3)2
K2Cr2O7
KCH3CO2
thanks if you can help, I can't find them anywhere

2007-03-13 17:58:39 · 2 answers · asked by Boo Radley 4

The carbonate ion (CO3 2-) acts as a Bronsted-Lowry base. What is the conjugate acid of the carbonate ion?
Write the chemical equation that includes both the carbonate ion and its conjugate acid.

I don't know how to write the eqution! :(
when i checked my answers during class, i got them wrong, and we didn't have much time to review the answers..

2007-03-13 17:54:52 · 3 answers · asked by Anonymous

Is it better to get higher values of the percent composition of calcium in the calcium supplement or lower ones, because mine are coming to be around 18 % and I m not being able to explain them clearly for my discussion.

2007-03-13 17:48:46 · 1 answers · asked by anshika g 1

how would you determine whether that substance has any solubility in water?

2007-03-13 17:47:53 · 3 answers · asked by ishika65 1

2007-03-13 17:46:56 · 1 answers · asked by Anonymous

2007-03-13 17:46:19 · 3 answers · asked by Anonymous

2007-03-13 17:38:29 · 3 answers · asked by Anonymous

Based on their electronic configuration, which of the following atoms are paramagnetic?
A) calcium
B) nitrogen
C) oxygen
D) argon
E) sulfur
F) iron

2007-03-13 17:35:47 · 4 answers · asked by bollocks 2

2007-03-13 17:34:01 · 2 answers · asked by bollocks 2

2007-03-13 17:29:23 · 2 answers · asked by Anonymous

2007-03-13 17:24:09 · 5 answers · asked by pyrocrazy4 1

A beaker with 195ml of an acetic acid buffer with a pH of 5.00 is sitting on a benchtop. The total molarity of acid and conjugate base in this buffer is 0.1M . A student adds 8.90ml of a 0.410 M solution to the beaker. How much will the pH change? The PKa of acetic acid is 4.76.

2007-03-13 17:22:44 · 2 answers · asked by bently 1

2007-03-13 17:18:40 · 4 answers · asked by me 2

Calculate the pH of the resulting solution when .5 gram of CsI is dissolved in 750 mL of water.

2007-03-13 17:16:40 · 1 answers · asked by me 2

Expaint which gas you would use to support combustion.
a.oxygen
b. hydrogen
c. carbon dioxide

2007-03-13 17:11:54 · 5 answers · asked by Johnnyboy 2

2007-03-13 17:10:22 · 1 answers · asked by bodkhan 1

We are making dulutions of 200 mL, so how would we get
4M NaOH (solid) into a liquid by doing stociometrey.

So basically- how would you be able to go from moles of a solid into a liquid amount of a solid- when this is the only infromation given.

We also got this equation. (Mcon * mL con= Mdil * mL Dil) but I dont think this equation is useful for this problem.

Please help. I need this by tomorrow!

2007-03-13 17:06:54 · 2 answers · asked by Anonymous

2007-03-13 17:00:53 · 1 answers · asked by bollocks 2

I'm typing a report on elements and I need to know how to type it on the computer, I can write it, but how do you do it?!

Thanks.

2007-03-13 16:56:50 · 6 answers · asked by Anonymous

data results for trial 1 are, (mass of salt+evaporating dish) is 42.5054g an a average Mass of evaporating dish(empty) at 42.4519g with a Mass salt of 0.0535g. The second trial being (mass of salt+evaporating dish) is 42.5924g an a average Mass of evaporating dish(empty) at 42.5807g and a Mass of salt at 0.0117.

(i am ask to calculate the Ksp)but i dont know how, can someone please explain, thanks in advance

2007-03-13 16:56:35 · 2 answers · asked by omar d 1

explain how a carbon atom within a CO2 molecule in the atmosphere ends up as a protein within a human muscle

2007-03-13 16:54:33 · 1 answers · asked by virgos_run_diz 2

Why is NaOH unsuitable as a primary standard?

2007-03-13 16:52:01 · 3 answers · asked by beuuu 2

What equipment can use to figure out the right dosing ? The water here is high in calcium Hardness 5930 mg/l sulfite 1015 mg/l total harness is 6240 as CaCO3 equivalent. We use a one pass system with 6 vessels each vessel has 3 RO membranes.

2007-03-13 16:47:58 · 2 answers · asked by miguelburg0a 1

2007-03-13 16:47:53 · 1 answers · asked by selle 1

A .12 M solution of an unknown, monoequivalent base has a pH of 9.99. Calculate the Kb for this base.

2007-03-13 16:42:49 · 2 answers · asked by me 2

periodic table

2007-03-13 16:38:55 · 2 answers · asked by oscar o 1

I have a test tomorrow in chem. and I need help with these 4 things:
1. Dilusion- How do you calculate it?
2. What does the term "Like dissolves like" mean in chemistry?
3.What are some examples of solute solvent combos...which is which?
4. Which has the most kinetic energy: solid, liquid, or gas

An answer to any of the 4 would be great : ]
Thanks

2007-03-13 16:36:40 · 4 answers · asked by Jennifer 2

given info:

enthalpy of sumlimation of calcium: 178.2 KJ/Mol

Br2(l)->Br2(g) H: 30.9

Enthalpy of formation for CaBr2 is -682.8 KJ

Ionization energy for Ca: 1:590
2:1145

Electron affinity for Br: -325

can you show me how to set up the Born-Haber cycle and how they cancel out?
THANK YOU SO MUCH!

2007-03-13 16:33:39 · 2 answers · asked by awe 2

How much lye would be necessary to completely dissolve a human body of approximately 180 lbs? and where can lye be purchased in large quantities?

2007-03-13 16:29:53 · 9 answers · asked by Anonymous