Chemistry - October 2007

3 questins; when looking at the periodic table how do you know if an element has any isotopes? what is a half-life element and how does it relate to isotopes? how is radioactivity released in an isotope?? need help with these!!

2007-10-31 01:49:33 · 3 answers · asked by ~~#1 cowgirl~~ 2

I have this one problem I do not get at all.

"A 0.1153 gram sample of a pure hydrocarbon was burned in a C-H combustion train to produce 0.3986 gram of CO2 and 0.0578 gram of H2O. Determine the masses of C and H in the sample and the percentages of these elements in the hydrocarbon."

Please also show workings so I understand it! Thanks. Best answer will be chosen ASAP.

2007-10-31 01:37:13 · 3 answers · asked by onlineworld 1

2007-10-30 22:08:33 · 8 answers · asked by bir.salem 2

2007-10-30 20:03:42 · 8 answers · asked by Adawg 3

2007-10-30 18:58:57 · 5 answers · asked by orange l 1

a science homework question about solubility in H2O.

2007-10-30 18:09:14 · 7 answers · asked by Anonymous

Does the air come up to the oxygen or vice versa?Or would they be about the same?

2007-10-30 17:41:24 · 5 answers · asked by Burnt Toast 1

Solution A is a solution of silver nitrate, and solution B is a solution of potassium chromate. The masses of the solutes in each of the solutions are the same. When the solutions are added together, a blood-red precipitate forms. After the reaction has gone to completion, you dry the solid and find that it has a mass of 331.8

(a) Calculate the concentration of the potassium ions in the original potassium chromate solution in M

(b) Calculate the concentration of the chromate ions in the final solution in M

2007-10-30 16:10:08 · 2 answers · asked by Troy p 1

please explain

2007-10-30 15:45:18 · 1 answers · asked by Anonymous

Benzene and toluene form an ideal solution. Consider a solution of benzene and toluene prepared at 25°C. Assuming the mole fractions of benzene and toluene in the vapor phase are equal, calculate the composition of the solution. At 25°C the vapor pressures of benzene and toluene are 95 and 28 torr, respectively.

x^L benzene ?

x^L toluene?

2007-10-30 15:28:10 · 1 answers · asked by Jake H 1

10 pts guaranteed to first correct answer
Use the responses below to answer the following questions.

a.) CH4
b.) NH3
c.) NaCl
d.) N2
e.) H2

1.) This substance undergoes ionic bonding(?) Would it be CH4?

2.) This Molecules contains two pi-bonds? N2

3.) This substance undergoes hydrogen bonding? NH3?

Which answers are for which? Why?

2007-10-30 15:27:07 · 3 answers · asked by Work Hard, Make Money, Enjoy Life... 3

A bottle of wine contains 12.3% ethanol by volume. The density of ethanol (C2H5OH) is 0.789 g/cm3. Calculate the concentration of ethanol in wine in terms of mass percent and molality.

mass percent?

molality?

2007-10-30 15:16:14 · 1 answers · asked by Jake H 1

list in the order from Largest to smallest.... atoms, neutron, electron, Carbohydrate, cow sugar, element, lipid, nucleic acid, protein, water, molecule, Corn, and nucleus.

2007-10-30 15:03:32 · 1 answers · asked by cheerleader4life!!! 2

it says to complete and balance the following chemical reactions...

I thought the answer would be HNO3(aq) +AgCl(aq)

but i looked at another question and someone said it was H2NO3 -> H20 + NO2 which makes no sense because the charge on Nitrate is -1 and the charge on hydrogen is +1
so umm which is the right answer ty

2007-10-30 14:53:25 · 5 answers · asked by Anonymous

2007-10-30 14:49:42 · 1 answers · asked by Anonymous

2007-10-30 14:46:55 · 2 answers · asked by Anonymous

2007-10-30 14:46:14 · 3 answers · asked by Anonymous

2007-10-30 14:33:38 · 1 answers · asked by Anonymous

[H+] = 0.00076 M

[H+] = 5.0 10-7M

a solution in which [H+] is five times greater than [OH -]

2007-10-30 14:30:53 · 1 answers · asked by JTOWN 2

I think it stands for mole x volume of first=mole x volume of the second. If I'm correct on this meaning why is it true?

2007-10-30 14:29:47 · 2 answers · asked by Anonymous

How would you write the diagram because I though MO only applies to two atom molecules. The book says the diagram should give me 2 sigma and one pi bond.

2007-10-30 14:26:44 · 1 answers · asked by Nhat t 1

like eg... helium symbol =He
atomic number = 2
Mass number = 4
Number of protons ?
Number of neutrons ?
Number of electrons ?

there mus be a table with that information no?

2007-10-30 14:25:49 · 2 answers · asked by Anonymous

2007-10-30 14:23:10 · 4 answers · asked by Anonymous

of Linus Pauling. I know that he did a lot, but what were his most important claims to fame?

2007-10-30 14:22:32 · 1 answers · asked by Ruth W 1

In nuclear reaction there is often a measurable difference in the masss of the reactants and the mass of products that is not the result of error in massing.What is the reason for the differences in mass Value?

2007-10-30 13:43:45 · 1 answers · asked by Ollie 1

2C8H18(l)+ 21 O2(g) --> 8CO(g) + 8CO2(g) + 18H2O
???delta H

Given
2C8H18(l) + 25 O2(g) ---> 16CO2 (g) + 18 H2O(l)
delta H -11,020 kJ

2CO (g) + O2 (g) --> 2CO2(g) delta H -566.0 kJ

2007-10-30 13:40:10 · 1 answers · asked by sophie's mom 1

i've heard that you can spray Axe or hairspray on your hand or anything else and light a match and it will catch on fire, but wont do any damage. is this true?

2007-10-30 13:39:17 · 6 answers · asked by katiboo:) 2

this problem says that i have a concentration of 9.00x10^18 molecules/cm^3 of NO. this isn't the correct unit for molarity right? how do i convert it to the correct moles/liters unit?

for the top, do i use avogadro's number? and for the bottom, convert to m^3? but i don't see how i can do that with the number.

thanks for your help!

2007-10-30 13:35:47 · 2 answers · asked by molly connolly 2

2007-10-30 13:34:01 · 1 answers · asked by carolyn 1

Urea (H2NCONH2) is used extensively as a nitrogen source in fertilizers.

2NH3 (g) + CO2 (g) --> H2NCONH2 (s) + H2O (g)

Ammonia gas at 223 C and 90. atm flows into a reactor at a rate of 500 L/min. Carbon dioxide at 223 C and 45 atm flows into the reactor at a rate of 600L/min. What mass of urea is produced per minute by this reaction assuming 100% yield?

2007-10-30 13:30:37 · 4 answers · asked by Anonymous