Chemistry - November 2007

as in single replacement, etc.
thanks!

2007-11-19 11:59:22 · 1 answers · asked by Anonymous

2007-11-19 11:53:39 · 6 answers · asked by Average Joes 4

Phosphorous pentachloride (PCl5) is used in the industrial preparation of many organic phosphorous compounds. Preparation of phosphorous pentachloride from PCl3 and Cl2 is given by the reaction :
(Eqn. 1) PCl3(l) + Cl2(g) PCl5(s)

Use the two equations below to calculate Hrxn of equation (1)

(Eqn. 2) P4(s) + 6 Cl2(g) 4PCl3(l)
H = -1280kJ

(Eqn. 3) P4(s) + 10Cl2(g) 4PCl5(s)
H = -1774 kJ

Hrxn = kJ

2007-11-19 10:14:48 · 3 answers · asked by Anonymous

Label each reaction as exothermic or endothermic ('exo' ir 'endo') and according to whether work is done on or by the system, or no work is doen at all ('on', 'by' or 'none')?

Pick either 'exo-none', 'exo-on', 'exo-by' or 'endo-by' for EACH of the following reactions:

a. N2(l) -> N2(g)
b. Cl2(aq) + 2KBr(aq) -> 2KCl(aq) + Br2(aq)
c. Zn(s) + 2HCl(aq) -> ZnCl2(aq) + H2(g)
d. NH3(g) + HCl(g) -> NH4Cl(s)
e. S(s) + 3/2O2(g) -> SO3(g)

2007-11-19 10:14:45 · 2 answers · asked by Anonymous

I get that it should have four bonds and 16 e-
I get the 16 e- part well, six dots on S, two bonds on P, six dots on S, but only with two bonds.

S=N-A
S=(8x3)-[5+(2x6)-1]
S=24-16
S=8 shared e-
S=4 bonds

Help.

2007-11-19 09:44:36 · 1 answers · asked by Pancha Pistolas 3

_Pb + _HNO3 ---> _Pb(NO3)2 + _NO + _HOH

all the numbers are the suscripts
PLEASE HELP... first answer will get the best answer if its correct! thanks!

2007-11-19 09:37:39 · 2 answers · asked by hellokitty729 1

(a) (CH3)3CNH2
(b) CH3NH2
(c) (CH3CH2)3CNH2
(d) all of these

2007-11-19 09:33:02 · 2 answers · asked by MK 1

When a chemist burns hydrogen according to the reaction below she finds that heat is released. (It is exothermic.)
2H2(g) + O2(g) 2H2O(g)

The enthalpy change for the reaction is H = -484 kJ. What is the enthalpy change per gram of hydrogen (in kJ/g)?

2007-11-19 09:32:16 · 3 answers · asked by Ryan H 1

One mole of an ideal gas is expanded at T = 300 K from a volume of 1.00 liter to a volume of 10.00 liters against a constant external pressure of 1.00 atm. How much work (in joules) is performed on the surroundings?

2007-11-19 09:27:18 · 1 answers · asked by Ryan H 1

1. find the molarity of a solution if 148 grams of sodium hydroxide is dissolved in enough water to make 3.8 L of solution?
2. find the number of grams of Magnesium Nitrate in 5.2 L of a 4.4 molar solution of magnesium nitrate.

2007-11-19 09:24:00 · 2 answers · asked by Anonymous

Hi,

In 1940 two chemists named Sidgwick and Powell came up with a theory on the structures of molecules and were the first to introduce the linear, trigonal planar, tetrahedral, trigonal bypyramid, and octahedral geometries. Although they developed the key molecular geometries, their theory was incorrectly stated: "Bonding pairs and lone pairs are of equal importance and distribute themselves to minimize interelectron repulsion." What fundamental modification did Gillespie and Nyholm add to Sidgwick and Powell's theory to develop the VSEPR theory that we use today? Give an example of two different molecules that violate the incorrect statement in the Sidgwic/Powell theory and give evidence as to why they violate the old theory?

Are bonding pairs more important and they try to get as far from one another as possible? It does seem like the bonding pairs and the lone pairs are of equal importance so I don't know what's wrong.

Thanks!

2007-11-19 09:14:21 · 3 answers · asked by Anonymous

I was wondering how you could use the half life method to prove a reaction was first order?

2007-11-19 09:05:28 · 1 answers · asked by Anonymous

how is this Bromine
n=4
l = 1
ml = 0
ms = -1/2

from this, i know that its in the 4th energy level and since l = 1, it must be in the 4p orbital. but i dont understand ml. how do i determine which element it is from the 4p orbital???

2007-11-19 08:51:14 · 1 answers · asked by Anonymous

2007-11-19 06:57:26 · 1 answers · asked by Anonymous

I have no idea....

For the following reaction at a certain temperature, it is found that the equilibrium concentrations in a 5.00 L rigid container are [H2] = 0.0500 M, [F2] = 0.0100 M, and [HF] = 0.400 M. If 0.330 mol of F2 is added to this equilibrium mixture, calculate the concentrations of all gases once equilibrium is reestablished.

H2(g) + F2(g) 2 HF(g)

[H2]=
[F2]=
[HF]=

2007-11-19 06:40:17 · 1 answers · asked by Lauren K 2

CH3CH2Br + OH(-) ==>

CH3CH2Br + (CH3)CO(-)==>

Which [E2] reaction in each pair is faster?

This deals with stronger nucleophile, stronger base, the stronger the nucleophile, which favors the E2 eraction. But which base is stronger? I say it's the OH, but some have said it's the other one (CH3)CO-. So which base is stronger, and WHY? Please include his as part of your answer. Thank you.

2007-11-19 06:00:00 · 1 answers · asked by Anonymous

A molecule with the formula AB_3 has a trigonal pyramidal geometry.

2007-11-19 05:45:45 · 1 answers · asked by Anonymous

a 5.00 liter sample of gas measured at 27.0 Celsius & 1.25 atm of pressure has a mass of 10.13 g. What is the molecular weight of gas in u?

a. 2.50 x 10 ^-2

b. 0.898

c. 39.9

d. 2.57

2007-11-19 05:06:17 · 3 answers · asked by Katrina Green 2

calculate the volume in gas in liters of of 3.50 moles of gas at STP.

a. 1.27

b. 0.721

c. 541

d. 1.08 x 10^3 torr.

2007-11-19 05:03:16 · 2 answers · asked by Katrina Green 2

Natural gas is very abundant in many Middle Eastern oil fields. However, the costs of shipping the gas to markets in other parts of the world are high because it is necessary to liquefy the gas, which is mainly methane and thus had a boiling point at atmospheric pressure of -164 C. One opossible strategy is to oxidize the methane to methanol, which has a boiling point of 65 C and can therefore be shipped more readily. Suppose that 1.07 x 10^10 ft^3 of methane at atmospheric pressure and 25 C is oxidized to methanol.

2007-11-19 04:45:17 · 1 answers · asked by DLCJ 2

2007-11-19 04:38:42 · 1 answers · asked by student217 1

so i'm making a solution of bromine in water and finding the concentration of this solution using a UV VIS spectrum and the beer-lambert law. What I'm wondering, is how do I know where to look on the graph to determine the concentration....mb this will be clear when I do the experiment, but I'm confused.
Can anyone help plzzzzzzz?

2007-11-19 04:32:18 · 1 answers · asked by Anonymous

what information cab be obtained by the neutral ferric chloride test ? Does this agree wiht the information obtained from IR spectrum of paracetamol?

2007-11-19 04:29:22 · 2 answers · asked by Shilpan Patel 1

the specific heat of ice is 0.48cal/g degree Celsius. how much heat will it take to raise temp. of 10 g of ice frm -30 C to -20 C?

a. 0.48 cal

b. 48 cal

c. 10 cal

d. 4.8 cal

2007-11-19 04:27:28 · 6 answers · asked by Anonymous

Does catalase( the enzyme in the liver and potato which catalyzed the reactions ) change hydrogen peroxide into none-toxic materials ? Explain

2007-11-19 04:21:15 · 1 answers · asked by LIZA 4

If a 1:1 dilution is an mix of equal parts, what is a 1:2 dilution? I always thought you subtracted the volume of the concentrated part from the final total volume. For instance, to make a 1:20 dilution, take one part of the concentrate and add 19 parts of the diluent so you'd have 1 part in a total volume of 20. Or do you add 1 part to 20 making the total volume 21?

2007-11-19 04:18:55 · 1 answers · asked by debodun 2

the heat fusion for zinc chloride is 40.4 calories per gram at the melting point of 275 Celsius. How much heat is required to melt 500 g of zinc chloride at its melting point.

a. 11.1 kcal

b. 1.80 cal

c. 12.4 cal

d. 20.2 kcal

could you please explain how you got the answer too.thanks a lot.

2007-11-19 04:17:04 · 4 answers · asked by Anonymous

A. all Hs are equivalent

B. 12

C. 2

D. 6

2007-11-19 04:16:30 · 2 answers · asked by student217 1

Could someone please give me a formula to convert mg/l or the E in beer lambert law into a percentage.
Thank you to anyone in advance for answering this question.

2007-11-19 03:36:55 · 3 answers · asked by Richard R 1

6CuCl(aq) + 2Na3N(aq) yields 2Cu3N(s) +6 NaCl (aq) + N2(g) I don't think this equation is balanced to begin with and I am even having trouble with that! Please show conversion steps.

2007-11-19 03:01:14 · 2 answers · asked by xraymom 1