Science & Mathematics - 4 December 2006

Write the balanced equation for the combustion of heptane and use the average bond energies to estimate the reaction energy (heat of combustion). Give your answer in kJ/mol of heptane . (Be sure to indicate the sign)

I keep getting -92, but that's not correct.

2006-12-04 11:48:40 · 1 answers · asked by Anonymous in Chemistry

2006-12-04 11:48:05 · 9 answers · asked by kit k 1 in Botany

Well the basis is there are 16 circles. Each line of 4 circles has to be equal to the other 7 lines, so each line must have the same number. EX. 34,,34,34,34,34,34 ..... You can only use numbers 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16 (1-16) and use each number once. This is really hard, ive been trying for hours. So imagine a square, each line on the circles having 4 circles. The top horizontal has 4 new circles. Then the left vertical has one of the top horizontal circles and 3 new ones. The bottom horizontal has 3 new ones and 1 of the left vertical, etc. Then imagine that square, then twist it. So now there is a new square, with 4 new circles, on the middle of each line. There will be a total of 8 lines. I cant draw it here, unfortuantly.

2006-12-04 11:47:45 · 4 answers · asked by the man homie 1 in Mathematics

any problem

2006-12-04 11:47:04 · 4 answers · asked by AmberG 1 in Mathematics

2006-12-04 11:46:09 · 2 answers · asked by Roy D 1 in Biology

Hey.. i am kinda stuck on this math question..
1/2x^2+x-1=0

im supposed to use, the completing the square method.. .can anyone help

2006-12-04 11:45:32 · 6 answers · asked by Anonymous in Mathematics

it's for an english assignment

2006-12-04 11:44:56 · 3 answers · asked by Anonymous in Engineering

Im wondering if anyone can help... Im doing a science course on the effect of dynamite when inserted up a Gerbals back passage and detonated...

I have to find out whether or not its head would remain intact..
Has anyone tried this and did it ????

I have tried this experiment twice as directed, but cant find any heads anywhere in the feild i used...I know it might seem like cheating, but im getting desperate and i really need the remaining three Gerbils for other experiments. Is anyone willing to help me out on this one.... ???
.

2006-12-04 11:43:35 · 14 answers · asked by pop c 2 in Zoology

Say you have:
CH3CH2CH2CH2OH + HBR=== CH3CH2CH2CH2BR + H20

Say your given quantities of 18.5 g of the first compound.

What is the molecular weight and the number of moles?

And how do you find the theorectical yield?

2006-12-04 11:43:32 · 1 answers · asked by Trevor M 1 in Chemistry

where not what are they.

2006-12-04 11:43:26 · 7 answers · asked by Michael J 1 in Mathematics

Thanks for reading this...I think I know how, but need a little reinforcement.
1) How many molecules are contained in 6.53 mol of nitrogen gas N2?
2) A sample of oxygin gas O2, weighs 28.4 g. How many molecules of O2, and how may atoms of O are present in this sample?
Thank you

2006-12-04 11:42:33 · 4 answers · asked by Anonymous in Chemistry

Calculate the net torque (magnitude and direction) on the beam in Figure P8.3 about the following axes.
http://www.webassign.net/sercp/p8-3.gif
figure 8.3 is above

(a) an axis through O, perpendicular to the page
(b) an axis through C, perpendicular to the page

2006-12-04 11:42:26 · 1 answers · asked by itsosheen 2 in Physics

Sorry for a stupid question, I'm in grade 9 and I'm working on a project.

2006-12-04 11:41:42 · 3 answers · asked by rewmmm 1 in Biology

Three salesmen are in town for a convention. needless to say motel rooms are sold out. Finally they find one, but it only has one room available. They ask the desk clerk how much it would cost for one night. Knowing he has the only room left for miles around, he decides to take advantage of the three men. He tells them that the room goes for $30.00 per night. They agree to this, and each man hands the clerk $10.00. This totals $30.00. The bellboy takes their bags up to the room and wiahes them a good night. Alittle while later the clerk has an attach of the gilts and calls the bellboy over and gives him $10.00 instructing him to go up to their room and explain to them that he over charged them and wished to make things right. While the bellboy was on his way up to their room he got thinking,,, the three men wouldn't know how much money the clerk gave him, so he puts $2.00 in his pocket. Now each man paid $9.00. 3 X $9.00 = $27.00 plus the $2.00 for the bellboy = $29.00. $1.00 missing ?

2006-12-04 11:41:14 · 7 answers · asked by wilkenmj 2 in Mathematics

in other words, how much life do they have left?

2006-12-04 11:41:00 · 2 answers · asked by Lone Ranja™ 3 in Astronomy & Space

I am planning to take USMLE, How can I prepare well for the tests & what should I expect?!
by the way.... I've never taken it before!

2006-12-04 11:38:52 · 8 answers · asked by Smart Warrior 1 in Medicine

I'm not talking about the more controversial embryonic stem research. I'm talking about just stem cell research in general...like adult stem cell research. Personally, I think this is an idiot question, but I have to answer it for a science project T-T Sources would be very, very beneficial.
Any help is appreciated!

2006-12-04 11:36:52 · 3 answers · asked by somebabo 2 in Biology

it's for an engllish assignment.

2006-12-04 11:36:43 · 1 answers · asked by Anonymous in Engineering

i just need some history on the subject.

2006-12-04 11:35:50 · 2 answers · asked by poohrox28 2 in Earth Sciences & Geology

For the reaction BaCl2 (aq) + ZnSO4 (aq) BaSO4 precipitates out.
Calculate the percent yield (%) if 13.084 g of BaSO4 precipitates
when 1.700 L of 0.0500 M BaCl2 (aq) and 2.180 L of 0.0300 M ZnSO4 (aq) are mixed.

2006-12-04 11:35:31 · 2 answers · asked by Andrew C 1 in Chemistry

2006-12-04 11:33:34 · 5 answers · asked by TyMill 1 in Physics

2006-12-04 11:32:42 · 6 answers · asked by je t'aime 3 in Mathematics

WOULD IT RUST

2006-12-04 11:32:04 · 20 answers · asked by Anonymous in Chemistry

2006-12-04 11:31:06 · 6 answers · asked by Anonymous in Chemistry

The question also adds that the amount dfference must also be specified. There is also a hint to allow the unstretched spring to be L1 and the stretched spring with the mass to be L2.

2006-12-04 11:29:29 · 1 answers · asked by Justin F 1 in Physics

What did scientists discover when they arranged elements in order from increasing atomic mass?

2006-12-04 11:29:11 · 2 answers · asked by Cathryn E. 2 in Other - Science

This is research I am doing for a chemistry project. I am looking for the actual conversion process.

2006-12-04 11:27:36 · 3 answers · asked by Nikki 2 in Other - Science

2006-12-04 11:27:34 · 2 answers · asked by Gideon 1 in Physics

Balance these & Idenify what types these are, I'm taking chemistry 1 only
1. CO --» C + O2
2. NaCI + AgNO3 -» NaNO3 + AgCl
3. S + Cl2 -* SCl2
4. BaCI2 + NaOH -» NaCI + Ba(OH)2
5. Zn + CuSO4 -> ZnS04 + Cu
6. CH4 -» C +H2
7. Pb(NO3)2 + Mg ---> Pb + Mg(N03)2
8. Mg + HCl >>> MgCL2 + H2
9. H2S04 ---> H2 + S +O2
lO. O2 + N2 >>> N2O4
11. CaBr2 +Na3P>>> Ca3P2 + NaBr
12. KI + Br2 >>>KBr + I2
13. C6H12O6 >>> C+ H2O
14. NaF >>Na + F2
15. Si + 02 ----> SiO2
16. Nal + Pb(NO3)2 >>>NaNO3 + PbI2
17. Nal + Cs >>> CsI + Na
18. H2 + CO + O2 >>>>H2CO3
19. Li3 PO4 >> Li + P + O2
20. CS2 + F2 >>> CF4 + S
Just Balance these out only::
21. Zn + O2>>ZnO
22. HI>>H2 I2
23. B + F2 >>> BF3
24. N2 + H2 >>NH3
25. Fe + H2O >>> Fe3O4 + H2

2006-12-04 11:27:12 · 5 answers · asked by truckin_90 2 in Chemistry

thanks...

2006-12-04 11:23:03 · 7 answers · asked by David S 2 in Mathematics