Chemistry - November 2007

2007-11-06 17:09:52 · 1 answers · asked by peace 3

a. sodium chloride
b. calcium fluoride
c. calcium chloride
d. water

pick one pleaseeeee!

2007-11-06 17:08:50 · 4 answers · asked by maingedang 5

how does polonium decay to xenon?

2007-11-06 16:46:44 · 1 answers · asked by goofygoober 2

The picture: C:\Documents and Settings\Kathryn\Temporary Internet Files\Content.IE5\XI9AG7LJ/chemistry_question_2[1].gif


In the figure above, the pressure of the gas in the 1.00 L bulb is 602 mm Hg and that of the gas in the 0.500 L bulb is 439 mm Hg.
(neglect the volume of the capillary tube connecting the bulbs)

2007-11-06 16:37:14 · 1 answers · asked by tibsy2007 2

You transferred 20. mL of acetic acid solution to an Erlenmeyer flask and added 2 drops of phenolphthalein solution. You filled your buret with 0.10 M NaOH so that the initial buret reading was 2.69 mL. After titrating your sample to the faint-pink phenolphthalein endpoint, the final buret reading was 17.19 mL.

1) How many moles of NaOH were delivered to the flask?

2)What is the concentration of the acetic acid solution?

2007-11-06 16:25:34 · 1 answers · asked by mark 2

Nickel has a face-centered cubic unit cell. The density of nickel is 6.84 grams per centimeter cubed
Atomic weight of Nickel = 58.71 g/mol

2007-11-06 16:08:33 · 1 answers · asked by unique_fantasy 1

what about a plant growing taller? is it a physical reation?

2007-11-06 16:07:57 · 8 answers · asked by Anonymous

How is it different from group II with Cl2
and Group I with Br2?

2007-11-06 16:04:43 · 1 answers · asked by K3iKo 1

If the pile of books has a mass of 12.60 kg, a length of 33.02 cm, a width of 33.02 cm, and
a height of 25.45 cm, how much pressure (N/m2) must the table be able to withstand at any place
where the books are placed ?

2007-11-06 15:57:27 · 1 answers · asked by Anonymous

You dissolve 0.33 g of KHP in 20 mL of water and titrate with the NaOH solution. To the nearest mL, calculate the volume of NaOH solution expected assuming that the NaOH concentration is ~0.1 M.

2007-11-06 15:54:06 · 2 answers · asked by poo 2

Substance X has a melting point higher than 500 degree celsius. It is insoluble both in water and in organic solvents. It conducts electricity both when solid and when molten. What could X be?

(1) copper
(2) magnesium oxide
(3) poly(ethene)
(4) silica
(5) sodium chloride

The answer is (1) copper..why? I don't understand..Please explain..Thanks.

2007-11-06 15:42:26 · 1 answers · asked by Anonymous

In a mixture of H2 and CH4 gases, the partial pressure of H2 is 0.120 atm. The total pressure is 0.415 atm. The temperature is 30.0oC. If the total volume of the gas mixture is 394 mL, what is the mass of CH4 in grams?

2007-11-06 15:33:56 · 1 answers · asked by metalmonkey71 1

in a Synthesis of Isopentyl Acetate (Banana Oil) lab can some one help me with this questions
1. What is the purpose of washing the organic layer with 5% aqueous sodium bicarbonate? Remember, you used an excess of glacial acetic acid.
2. What is the purpose of washing with 25 mL of water?
3. Why is it necessary to record the barometric pressure when distilling at atmospheric pressure?

2007-11-06 15:29:16 · 5 answers · asked by Anonymous

An organic compound contains C, H, N, and O. Combustion of 0.1023 g of the compound in excess oxygen yielded 0.2766 g of CO2 and 0.0991 g of H2O. A sample of 0.4831 g of of the compound was analyzed for nitrogen by the Dumas method. At STP, 27.6 mL of dry N2 was obtained. In a third experiment the density of the compound as a gas was found to be 4.02 g/L at 127°C and 256 torr. What are the empirical formula and the molecular formula of the compound?

I got C24H42O3N for the empirical formula. but that is totally wrong. could someone please help me
please and thank you

2007-11-06 15:13:39 · 1 answers · asked by Yongsun S 2

102. mL of a solution of quinine contains 206.0 x 10-3 mol of quinine. If this is titrated with 0.0200 M HCl, what is the pH at the stoichiometric point? Quinine is monobasic with
Kb = 7.90 x 10-6

thanks!!!

2007-11-06 15:12:23 · 1 answers · asked by TBMlover 1

Calculate the pH of the solution that results from the addition of 0.020 moles of HNO3 to a buffer made by combining
0.500 L of 0.290 M HC3H5O2 ( use Ka = 1.30 x 10 -5 )
and 0.500 L of 0.580 M of the conjugate base of acid ?

thanks!!

2007-11-06 15:11:42 · 1 answers · asked by TBMlover 1

please respond ASAP
thanks!

2007-11-06 14:56:41 · 6 answers · asked by cowsgomoo123 2

I really don't get this. I have tried to do what I could on my own with no luck! Help please! It looks lengthy so any help is appreciated! Show steps so I can get a understanding!

1. Consider the titration of 35.0 mL of 0.165-M of KX with 0.078-M HCl. The pKa of HX = 5.21. Give all pH values to 0.01 pH units.
a) What is the pH of the original solution before addition of any acid?
b) How many mL of acid are required to reach the equivalence point?
c) What is the pH at the equivalence point?
d) What is the pH of the solution after the addition of 37.0 mL of acid?
e) What is the pH of the solution after the addition of 88.8 mL of acid?

2007-11-06 14:47:50 · 1 answers · asked by crazygirl0630 2

2007-11-06 14:41:21 · 1 answers · asked by sojo3 1

A.NaCLO3
B.NH4CLO4
C.(NH4)2CrO4
D.FE(OH)3

plzz help im desperate!

2007-11-06 14:35:54 · 2 answers · asked by manny 1

Ok so my teacher really confused me when going over this in class! Please help, I have no clue! Please show your steps. Any help appreciated!

Calculate the pH of each of the solutions and the change in pH to 0.01 pH units caused by adding 10.0 mL of 2.77-M HCl to 400. mL of each of the following solutions.
Change is defined as final minus initial, so if the pH drops upon mixing the change is negative.
a) water
pH before mixing =
pH after mixing=
pH change =

b) 0.193 M C2H3O21-
pH before mixing =
pH after mixing=
pH change =

c) 0.193 M HC2H3O2
pH before mixing =
pH after mixing=
pH change =

d) a buffer solution that is 0.193 M in each C2H3O21- and HC2H3O2
pH before mixing =
pH after mixing=
pH change =
Link to acid base table: http://www.webassign.net/wertz/caqs/html/resource/acidbase_pka.html

2007-11-06 14:35:16 · 1 answers · asked by crazygirl0630 2

why???

2007-11-06 14:34:30 · 4 answers · asked by Tone 2

Looks simple enough yet I can't come up with the correct answers. Help please! Please show steps...any help appreciated!

1. What is the pH (to nearest 0.01 pH unit) of a solution prepared by mixing 54.0 mL of 0.0397 M NaOH and 67.0 mL of 0.0203 M Ba(OH)2?

2. What is the pH (to nearest 0.01 pH unit) of a solution prepared by mixing 83.0 mL of 0.526 M HCl and 78.0 mL of 0.595 M NaOH?

Link to acid/base table: http://www.webassign.net/wertz/caqs/html/resource/acidbase_pka.html

2007-11-06 14:30:18 · 2 answers · asked by crazygirl0630 2

I'm having a terrible time with this. Please help so that I will begin to understand! Please show your steps! I know it looks long so any help at all would be appreciated!

1. What is the value of the equilibrium constant (three sig figs) for the reaction of hydrofluoric acid and ammonia?
K =
Fill in the following reaction table with mmol (to the nearest 0.01 mmol) for the reaction occurring when 44.7 mL of 0.222-M ammonia are mixed with 27.6 mL of 0.292-M hydrofluoric acid.
HF + NH3 ↔ F1- + NH41+
initial
delta
final
What is the final concentration of ammonium ion to three significant figures?

How many mmols (three sig figs) of the limiting reactant are actually present at equilibrium? This value is not based on the final amount shown in the table because the table assumes complete reaction (not equilibrium) of the limiting reactant.

Link to acid/base table: http://www.webassign.net/wertz/caqs/html/resource/acidbase_pka.html

2007-11-06 14:27:18 · 2 answers · asked by crazygirl0630 2

A solid is insoluble in water but dissolves in aqueous acid and in aqueous alkali without evolution of a gas in either case.

What could the solid be?

(1) copper(II) carbonate
(2) copper(II) hydroxide
(3) sodium carbonate
(4) zinc carbonate
(5) zinc hydroxide

The answer is (5) zinc hydroxide..I don't understand..please explain..Thanks.

2007-11-06 14:17:17 · 4 answers · asked by Anonymous

2007-11-06 14:14:01 · 4 answers · asked by Jenna 2

3. Calculate the density, g/cm3, of carbon dioxide at 103.0oC and 818 torr.

4.A mixture of 5.90 g of O2 and 10.3 g of Xe exerts a pressure of 0.480 atm.
What is the partial pressure, in atm, of the O2 gas ?

5.In a mixture of H2 and CH4 gases, the partial pressure of H2 is 0.155 atm. The total pressure is 0.375 atm. The temperature is 34.0oC. If the total volume of the gas mixture is 445 mL, what is the mass of CH4 in grams?

Any help will be much appreciated!!

2007-11-06 14:07:46 · 3 answers · asked by matt b 1

Cumene containing only carbon and hydrogen is used in the production of acetone and phenol, combustion of 47.6mg cumene produces some CO2 and 42.8mg water. The molar mass of cumene is between 115 and 125 g/mol. determine the empirical and molecular formulas...

now I've been working on it forever and if any one could tell me the steps to get to the answer of C3H4, C9H12 that were given it would be MUCH appreciated

2007-11-06 14:04:14 · 1 answers · asked by Anonymous

The element Palladium (Pd) has the electron configuration 4d^10 5s^0. Why does this element have the S orbital noted if it is empty?

2007-11-06 13:56:47 · 4 answers · asked by rexhenry11 2

Im not sure wat equation of molarity to use so yeah...

2007-11-06 13:28:19 · 3 answers · asked by Anonymous