Chemistry - June 2007

The two naturally occurring isotopes of copper are copper-63, with a mass of 92.9298u and copper-65, with a mass of 64.9278u. If the tabulated atomic mass of copper is 63.546u, what must be the percent natural abundances of the two isotopes? Please solve for x - it has been too many years since algebra.

Thanks

2007-06-05 13:31:53 · 1 answers · asked by thenursejenn 1

1,6-heptadiene

2007-06-05 13:19:28 · 2 answers · asked by pamoberst 2

2007-06-05 13:11:39 · 1 answers · asked by atljasmine4 1

people say that when you put it in water it catchs fire!
so where can I buy pure sulfer?

2007-06-05 12:56:42 · 2 answers · asked by Andrew Q 2

NBr3 + 3H2O --> 3HOBr + NH3
The energy exchange associated with this reaction in -81 kJ.
Use this information to calculate the energy of the N-to-Br bond. Assume all atoms other than hydrogen obey the octet rule.

Thanks!!! Any help is welcome!!

2007-06-05 12:53:54 · 1 answers · asked by Anonymous

what is the physical state (solid, liquid, gas) of substance A at room tempreature? At 0 degree C and at 100 degrees celsius

2007-06-05 12:52:09 · 2 answers · asked by Anonymous

What is the mole fraction of lactose in the solution? I keep coming up with .358, is that correct?

2007-06-05 12:50:16 · 1 answers · asked by janeeyre444 1

61.)
what is the freezing point of a solution that contains 0.5 moles of Nal in 500g of water? (Kf = 1.86C/m; molar mass of water = 18g)

please help and explain this to me??
i have a test 2mrow

<3

2007-06-05 12:45:20 · 2 answers · asked by lalagurl94 1

2007-06-05 11:52:10 · 3 answers · asked by pgarrios 1

Do you know how to find empirical and molecular formulas? I have a semester test tomorrow, and I have no clue what to do. All I know is that you need to know the empirical to find the molecular. Please help.

Ex.: Ribose has a molecular mass of 150 g/mol and a chemical comp of 40% C, 6.67% H, and 53.3% O. What is the molecular formula?

Ex.: A compound was analyzed in a lab to determine its empirical formula. It was determined to be 9 g C, 16.8L H, and 2.8L O. What is the molecular formula if the molar mass is 116g/mol?

2007-06-05 11:39:16 · 3 answers · asked by Bridget 1

A 2L lab sample is at 72 degrees celcius a pressure of 4atm. What will be the new pressure if the sample is heated to 89 degrees celcius and compressed to 1.5L?

2007-06-05 11:30:40 · 3 answers · asked by Mander 1

And which is lower in energy, a mix of hydrogen and oxygen gases or liquid water?
Thanks!!

2007-06-05 11:30:12 · 3 answers · asked by jessieroo19 2

2007-06-05 11:23:45 · 14 answers · asked by kitcat 1

I have a homework assignment that states:
A decomposition reaction has a rate constant of 0.0012 yr ^ -1

Since the prime exponent is after the units, what the heck does this mean? I have never seen this before. Thanks for your help in advance.

2007-06-05 11:11:50 · 2 answers · asked by Erin L 1

Okay, so..This is a Combined Gas law problem.

I know the equation but i cant get it to work out on here...so if you know how to work out this problem..PLEASE help!!!! Thanks!

2007-06-05 10:58:14 · 2 answers · asked by Mander 1

How many grams of CH3COOH, acetic acid, a monoprotic acid, would be needed to reach an end point with 45.61 mL of 0.175 M KOH?

2007-06-05 10:55:53 · 3 answers · asked by Anonymous

1. What pressure will 26g of helium exert when placed in a steel clinder at 200 degrees Celsius?
2. The vapour pressure of water at 21 degrees Celsius is 2.5kPa. Calculate the minimum volume occupied by 1g of water at this temperature?
3. What is the density of hydrogen at 200 degrees Celsius and 200kPa? (Assume a volume of 1L)

2007-06-05 10:55:01 · 1 answers · asked by Anonymous

2007-06-05 10:49:46 · 5 answers · asked by Anonymous

convert mL to L

2007-06-05 10:13:09 · 12 answers · asked by Jasmeen 3

What mass of sodium (density .968) would have twice the volume of 82.5 gram sulfur (denisty 1.96)?

Thanks so much, in advance. This is a practice sheet I got for I test I'm taking Friday and I have no idea.

:)

2007-06-05 09:58:05 · 1 answers · asked by merryboat707 1

2007-06-05 09:34:26 · 2 answers · asked by Anonymous

Vitamin B3 also known as niacin helps maintain the normal function of the skin, nerves and digestive system. The disease pellagra results from a severe niacin deficiency. Niacin has the following formula: C6H5O2. Often tablets contain vitamin B3 in the form of niacinamide C6H6N2O which is easier to absorb. A vitamin tablet contains 100mg of niacinamide
a) What mass of niacin contains an equivalent # of moles as 100mg of niacinamide?

2007-06-05 09:17:12 · 3 answers · asked by John J 1

how to prepare a buffer solution, 1L-volume, 0.05-Concentration, pH-7.4

2007-06-05 09:02:34 · 3 answers · asked by w girl. 1

2007-06-05 08:56:16 · 4 answers · asked by bico a 1

2007-06-05 08:26:00 · 19 answers · asked by Anonymous

how do I complete this nuclear reaction and name the decay process that is occuring 47Ca=47Sc+?

2007-06-05 08:21:39 · 2 answers · asked by mommy Ty 3

how do I complete this nuclear reaction and name the decay process that is occuring 47Ca=47Sc+?

2007-06-05 08:21:37 · 1 answers · asked by mommy Ty 3

What is the primary element that's added to steel to make stainless steel?

2007-06-05 08:12:48 · 7 answers · asked by kitcat 1

state the test and expected results please?

2007-06-05 07:43:23 · 14 answers · asked by goth :) 1

the combustion of methanol produces carbon dioxide gas and water vapor.
2CH3OH(l) + 3O2(g) --> 2CO2(g) + 4H2O(g)
what mass of water vapor forms when 52.4g of methanol burn?

there are a lot of these types of questions on my homework and i don't understand how to do them. can someone please show me how step by step? thanks

2007-06-05 07:24:11 · 6 answers · asked by sxe_afi_fallchild 1