Chemistry - September 2006

Silicon has 3 isotopes, Si-28, Si-29, and Si-32.
If the mass (amu) of Si-28 is 27.98 with abundance of 92.21% and the mass of Si-32 is 29.97 3.09%, what is the mass of Si-29 with an abundance of 4.70%?
i dont know if abundance has anything to do with finding the mass, but just put it.
do i have to find the average mass (add the masses of Si-28 and 32 together and divide by 2?)
help please!!!! :) THANKS!

2006-09-14 12:23:54 · 5 answers · asked by Anonymous

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2006-09-14 12:21:08 · 3 answers · asked by substance 2

Does anyone know where I can buy a small portion of strontium carbonate?

2006-09-14 12:13:38 · 2 answers · asked by ellyn2667 2

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2006-09-14 11:53:23 · 6 answers · asked by Anonymous

also she needs electromotive force of those elements and the heat combution of those elements and the reactivity with water and natural state can you help

2006-09-14 11:25:33 · 2 answers · asked by Ariel 1

Does the Table list all possible stable configurations of atoms, or is it possible that somewhere could exist elements that don't fit into the standard model? Is it believed that the entire universe is composed of the 115-odd substances listed on the Table?

2006-09-14 11:24:39 · 5 answers · asked by AmigaJoe 3

im my chem hw, there a table, and you have to calculate the mass, moles, molecules, and total number of atoms in a sample.
each of these samples is a compound, like H2O for example. i found the number of molecules, but to find the number of atoms would i multiple the number of molecules by 3 (the number of atoms in H2O? or is this wrong? Is there another way to do it?
I mean the mole number is 6.02 X 10^23 molecules or atoms, but when u have a compound, what is the total number of atoms?
help plz!
thnx!!!!!

2006-09-14 11:06:31 · 0 answers · asked by Anonymous

I have heard that you can extract codeine from Tylenol, I have even seen the poor man's guide of how to do it but it says you need AC&C, Tylenol #1.
I was just wondering if you can extract Codeine from Tylenol Extra Strength 500 mg. Becuase I have also heard from my pharmacist friend that all tylenol has a tiny amount of codiene. Anyone know...and don't say stupid ****.

2006-09-14 11:00:20 · 7 answers · asked by Ginny 2

Please help me. i dont know how to set up this conversin.

A 61 kg sample of water absorbs 315 kJ of heat. If the water was initially at 22.1°C, what is its final temperature?
________°C

2006-09-14 10:51:25 · 3 answers · asked by Krazyk78 1

Multiply, we are doing significant figures, and the answer has to be rounded(to the number of that has the least amount of signficant values.
18.2cm*8.4cm

help??

2006-09-14 10:30:58 · 6 answers · asked by Stephanie 3

Potassium permanganate and iron(II) sulphate reacting in the presence of dilute sulphuric acid.

2006-09-14 10:13:25 · 5 answers · asked by nessie_mils 2

If so, why? I do not get this. Please, I am a high school freshman trying to pass! And no, this is not the exact question on my homework, and no, I am not being lazy, I just hope some one will be able to describe it in laymans terms.

2006-09-14 10:12:49 · 7 answers · asked by Kathryne 1

2006-09-14 10:12:06 · 18 answers · asked by rob l 1

Please help, I need this by tonight! Thanks = )

2006-09-14 10:05:27 · 5 answers · asked by Miss*Curious 5

I had an aluminum slug that I measured the mass of as 8.669g.

The length was 2.8cm

The diameter was .950 cm

The volume (using a volumetric cylinder) was 3.5cm^3^. We are supposed to do a calculated volume using (pi*r^2*h) also..but when I do it with the formula, it doesn't come out the same both ways. I think I'm following everything, but it's just not coming close to being equal. Am I doing something wrong, or did we (more than likely) not measure something right?

2006-09-14 09:55:15 · 2 answers · asked by buttercup1137 2

2006-09-14 09:44:12 · 3 answers · asked by Steven H 1

this is with two component system.

2006-09-14 09:20:42 · 4 answers · asked by Fai 1

Can someone help me find the molecular weights of B Lymphocytes, Vaccine virus, gamma globulin, and ribozyme?

I can't find the molecular weights anywhere.

Thanks

2006-09-14 09:17:49 · 3 answers · asked by mking785 2

2006-09-14 09:00:02 · 3 answers · asked by nikki 1

a substance or something that is not made up of any chemicals or has no chemicals in it at all help it is in my test

2006-09-14 08:50:58 · 13 answers · asked by A.A 2

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2006-09-14 05:59:32 · 5 answers · asked by ? 3

for the pH testing

2006-09-14 05:57:38 · 2 answers · asked by Marrie-Lynne Louise L 1

2006-09-14 05:41:29 · 4 answers · asked by weirdpunkaj_0622 1

white sugar
white wine
lemonade
shampoo
hair conditioner
laundry detergent

I don't have anymore pH strips to do these. Does anyone know?

2006-09-14 04:45:36 · 4 answers · asked by coastey 1

2006-09-14 04:42:40 · 2 answers · asked by Anonymous

A gas is contained in a cylinder with a sliding piston. Weights are placed on top of the piston that produce a pressure of 70588 Pascals. Heat is removed as a quantity of energy equal to 3000 J The volume of the gas is reduced from 185.0 L to 84.4 L.


Calculate DE for the process in Joules.


expansion work = −PextΔV Pext = external pressure

2006-09-14 04:39:00 · 1 answers · asked by crazycuty4eva 1