Chemistry - March 2007

got a bar which ive had for a long time if it was brass it would of gone green by now or some other colour ,it says its 9.999 on the front how do i find out without takeing it to the shops to see if it is gold

2007-03-07 01:24:49 · 17 answers · asked by bud1658 2

2007-03-07 00:57:06 · 2 answers · asked by Anonymous

2007-03-07 00:55:30 · 2 answers · asked by Anonymous

i wanna know 'bout bleaching, especially when it comes to flour.. hehe.. gimme some help der! :D

2007-03-07 00:49:12 · 4 answers · asked by :) 3

2007-03-07 00:41:07 · 4 answers · asked by Anonymous

Al reacts with excess copper II sulfate according to the reaction below. If 1.85g of Al react and the percent yeild of Cu is 56.6 what mass of Cu is produced?

2007-03-07 00:23:55 · 2 answers · asked by sweetangelbaby89_2004 1

2007-03-07 00:05:00 · 2 answers · asked by anarchygirl 1

2007-03-06 23:35:37 · 4 answers · asked by curlash 1

this has to be about 3 pages long i need help!

2007-03-06 23:32:52 · 1 answers · asked by Anonymous

need to make this into a 5 page essay need good web site links!

2007-03-06 23:31:04 · 1 answers · asked by sarah2mee 1

2007-03-06 22:35:21 · 3 answers · asked by tosin a 1

2007-03-06 20:36:17 · 3 answers · asked by gbee101 1

Which of the following statements incorrectly describe ionic compounds?

i.They never contain covalent bonds

ii.They are formed when atoms share their valence electrons

iii.They are usually solids at room temperature

iv.They are generally gases at ice water temperature




a. i, ii, and iv

b. iii only

c. i and ii

d. ii and iv

e. iii and iv

2007-03-06 20:29:41 · 4 answers · asked by satish r 1

2007-03-06 20:08:38 · 1 answers · asked by anghad k 1

2007-03-06 19:42:28 · 5 answers · asked by ms_mw_2004 1

When radio active nuclids decay the change of the number of atoms depend on decay rate,How is yhis?

2007-03-06 19:16:14 · 2 answers · asked by teklemariam t 1

calculate the final concentrations of K+(aq), C2O4(aq), Ba2+, and Br- in a solution prepared by adding .1L of .2M K2C2O4 to .15L of .25 M BaBr2. for BaC2O4, Ksp=2.3E-8

a few drops of each of the indicators shown in the table were placed in separate portions of 1M solution of a weak acid, HX. the results are shown in the alst column of the table. what is the approximate pH of the solution containing HX? calculate the approximate value of Ka for HX.
Indicator color of HIn Color of In- pKa of HIn HX
bromphenol yellow blue 4.0 blue
blue

bromcresol yellow purple 6.0 yellow
purple

bromcresol yellow blue 4.8 green
green

alizarn yellow red 6.5 yellow

2007-03-06 19:02:29 · 2 answers · asked by Anonymous

cacodylic acid, (CH3)2AsO2H, a weak acid, is used in preparing buffered solutions. for the reaction pKa=6.19: (CH3)2AsO2H+H2O->H3O+(CH3)2AsO2- , calculate the masses of cacodylic acid and sodium cacodylate that should be used to prepare 500mL of a buffer at pH=6.6 that has a total concentration of all arsenic-containing species equal to .25M. that is (CH3)2AsO2H+(CH3)2AsO2-=.25M

one method for determining the purity of aspirin is to hydrolyze it with NaOh solution and the titrate the remaining NaOh. aspirin molar mass = 180.16g/mol. it is reacted with 2OH- and let boil for 10 min. then saliculate ion and acetate ion and water forms. a sample of aspirin with a mass of 1.427g was boiled in 50mL of .5M NaOH. after the solution was cooled, it took 31.92mL of .289M HCLto titrate the excess NaOH. Calculate the purity of the aspirin. What indicator should be used for this titration? why?

2007-03-06 18:57:37 · 1 answers · asked by Anonymous

2007-03-06 18:24:21 · 2 answers · asked by perfectionistjc 2

2007-03-06 18:18:12 · 6 answers · asked by Anonymous

In practical experiment,we find the Molarity of NaOH(aq) by reating with HCl(aq).We use 2 different indicators (methyl orange(change from orange to rad) and phenolphthalein(change from pink to colourless))to realise when the solution is neutralized.The question is "Was there any difference in the volumn of acid added using the 2 different indicators?Explain why?
My result was the volumn of acid for methyl orange indicator is greater than phenolphthalein.

2007-03-06 18:11:29 · 1 answers · asked by beuuu 2

2007-03-06 17:49:22 · 3 answers · asked by Anonymous

2007-03-06 17:43:06 · 2 answers · asked by Anonymous

2007-03-06 17:20:39 · 3 answers · asked by Kevin 2

on the ACTIVATION ENERGY OF THE REACTION or HEAT OF REACTION ?

2007-03-06 17:12:54 · 2 answers · asked by Xquisite Shawtey 1

The vapor pressure of pure water at 110 degrees C is 1070 torr. A solution of ethylene glycol and water has a vapor pressure of 1.00 atm at 110 degrees C. Assuming that Raoult's law is obeyed, what is the mole fraction of ethylene glycol in the solution?


If you could give clear steps in your answer, as to HOW to did it, that would be great. I'm not looking for the answer- if you choose to check, it's .290, i'm looking for how to go about it. i know you use raoult's law, i just don't know where!

thank you!

2007-03-06 17:08:58 · 2 answers · asked by bree 3

2007-03-06 17:02:32 · 2 answers · asked by Albert M 1

What are the parameters required to select Density Analysers

2007-03-06 17:00:38 · 1 answers · asked by Caprice classic 1

iths an halide compound

2007-03-06 16:51:02 · 9 answers · asked by lovekesh d 1

What is the molarity of a solution prepared by diluting 150. mL of 0.403 M HNO3 to 450. mL

2007-03-06 16:43:43 · 3 answers · asked by Pat M 1