Number of results: 109,489
Can ANYONE please help me by going to either the very bottom of this page or the top of the next and click on "English-URGENT-HELP NEEDED!"? I really need some help on that one and I'm afraid no one will find it and I'll have to keep posting it over and over. THANK-YOU ...
Sunday, August 26, 2007 at 4:13pm by Anonymous
chemistry URGENT (1)
(26.4mL)(1.00g/mL) = 26.4g H2O To raise the temperature of 26.4 g H2O by (16.4 C- 10.0 C), we need: (4.18 J/g.C)(26.4 g)(6.4 C) = 706 J needed - 82.8 kJ.mol-1 CaCl2 is equivalent to: 82800 J / 111g CaCl2 = 746 J/g CaCl2 released. Use the values: 706 J needed and 746 J/g CaCl2 ...
Sunday, November 16, 2008 at 2:18pm by GK
Hi, can you tell me what is needed to ionise the O^6+ ion further in order to turn it into an O^7+ ion ? Thanks.
Saturday, May 2, 2009 at 12:12pm by mathew -b
Chemistry Urgent Help
according to the balanced equation, for each one mole of Na2S one mole ofBi(NO3)3 is needed. So how many moles of each do you start with? The lower number will be the limiting reactant. THis number will also be the number of moles of Bi2S3 produced, convert that to grams.
Thursday, January 7, 2010 at 4:29pm by bobpursley
URGENT help! 3. A rock sample was dated using potassium-40, Neasyrenebt ubducated tgat 1/8 of the original parent isotope is left in the rock sample. How old is the rock? 5. When a sample of lava solidfied, it contained 28g of uranium-238. It that lava sample was later found ...
Friday, March 5, 2010 at 4:49am by Anon
Hi, I have a few chemistry problems that I'm having trouble solving. I put my attempted solutions after the problems in *'s. There was one problem I had no idea how to solve. What concentration of silver chromate (Ksp = 9.0 x 10-12) will dissolve to make a saturated solution ...
Monday, April 12, 2010 at 9:35pm by Maggie
HNO3 + KOH ==> KNO3 + H2O moles HNO3 = 2000 x 1 x 10^-3 = 2 mmoles. moles KOH = 2ooo x 1 x 10^-2 = 20 mmoles. Why subtract. This is an acid/base reaction, they neutralize each other. ALL of the HNO3 is GONE and you are left with an excess of 20-2 =18 mmoles KOH. So (OH...
Sunday, May 2, 2010 at 11:59pm by DrBob222
Chemistry- urgent help needed
How do I prepare 40% v/v from 95% ethanol? When we say 95% ethanol, do we usually mean 95% w/w ethanol unless otherwise stated? Please show me the calculation steps to prepare 40% v/v from 95% w/w ethanol. Thanks.
Sunday, September 19, 2010 at 6:08pm by annie
Chemistry - urgent
What form of NaOH did you use? Assume granular. moles NaOH=3/40 moles HCl needed= 3/40=volume*Molarity so lets see what 7 ml will neutralize molarity=3/40/.007= or about 10Molar. 32Percent HCl is about 10M
Tuesday, September 21, 2010 at 10:03am by bobpursley
Chemistry - repost
Why 7ml of 10M HCl? Do I add 7ml of 10M HCl 1st slowly in ice bath, then slowly adjust the pH to 7 using 10M HCl? Then to dilute to 15ml in a graduated cylinder? Thanks Posted by candy on Tuesday, September 21, 2010 at 10:03am. The following is part of a procedure for a limit ...
Tuesday, September 21, 2010 at 3:12pm by candy
Chemistry - bobpursley pls help
Posted by candy on Tuesday, September 21, 2010 at 3:12pm. Yes, my NaOH is granular. Why 7ml of 10M HCl? Do I add 7ml of 10M HCl 1st slowly in ice bath, then slowly adjust the pH to 7 using 10M HCl? Then to dilute to 15ml in a graduated cylinder? Thanks Posted by candy on ...
Tuesday, September 21, 2010 at 4:47pm by candy
Chemistry - more advice needed thanks
I obtained a lot of dirty brown ppt the moment the mixture was poured into AgNO3 solution. Does this mean my NaOH sample contains a lot of chlorides? Could other silver halides be present? However for my control solution of 50ppm sodium chloride solution,a cloudy white ppt was...
Tuesday, September 21, 2010 at 4:56pm by candy
Chemistry - pls help
This is a limit test for chlorides. 1.0g of NaOH sample was dissolved in 5ml of deionized water, acidified with 4ml of dilute nitric acid and diluted to 15ml with deionized water. (Test tube A) 10ml of 50ppm Standard NaCl solution was prepared. 5ml of water was added, follwed ...
Wednesday, September 22, 2010 at 5:31pm by candy
Chemistry - urgent help needed
The following is part of a procedure for a limit test for sulphates in an NaOH sample:- Dissolve 3.0g of NaOH in 6ml of deionized water, adjust to pH 7 with 12M HCl (about 6.2ml) and dilute to 15ml with deionized water. When about 6ml of 12M HCl was added, a white ppt was ...
Wednesday, September 22, 2010 at 6:03pm by candy
Chemistry - urgent help needed
You have now specified 12 M HCl, that is not dilute. The white ppt was NaCl not in solution. You added a lot of Cl ions with the 12M acid, you already had Na ions. So many, they could not go into solution.
Wednesday, September 22, 2010 at 6:03pm by bobpursley
urgent help needed!!! what is .0966 rounded to 2 significant digits? and why?
Wednesday, September 22, 2010 at 6:37pm by Ana
Hi,there was an error with the procedure. 1.0g NaOH sample was dissolved in 5ml of water and acidified with 4ml of conc. nitric acid,not dilute nitric acid. This was then made up to 15ml with water.After acidifying with conc. nitric acid instead of dilute nitric acid, no such ...
Thursday, September 23, 2010 at 4:38pm by candy
if 500 ml of HCl solution is needed to react with 2.43 g of Mg, what is the molarity of the HCl solution?
Tuesday, November 30, 2010 at 1:14pm by Lynn
hydrogen gas is collected in a bottle, and the pressure of the gas is 892 torr at 24 °C. what is the pressure of hydrogen gas when the temperature decreases to 20 °C? chemistry - DrBob222, Tuesday, November 30, 2010 at 1:25pm (P1/T1) = (P2/T2) Dear Dr Bob: is this a right ...
Tuesday, November 30, 2010 at 3:30pm by Lynn
if 100 g of iron were reacted with 100 g of oxygen according to the reaction below, the maximum yield in grams of Fe2O3 would be: chemistry urgent - bobpursley, Tuesday, November 30, 2010 at 4:20pm Balance the equation. Note the coefficents on Fe and O2, that is the mole ...
Tuesday, November 30, 2010 at 4:33pm by lynn