Wednesday
August 20, 2014

Posts by Sarah H


Total # Posts: 32

Chem -plz check work
so i've worked on this some more, now I am asking if someone will plz check my work 2 half cells in a galvanic cell consist of one iron Fe(s) electorde in a solution of iron (II) sulphate FeSO4(aq)and a silver Ag(s) electrode in a silver nitrate solution, a)state the ...
June 3, 2008

grade 12 chemisstry
I have no idea what I'm doing here, please help. 2 half cells in a galvanic cell consist of one iron Fe(s) electorde in a solution of iron (II) sulphate FeSO4(aq)and a silver Ag(s) electrode in a silver nitrate solution, a)state the oxidation half reaction, the reduction ...
June 3, 2008

grade 12 chem - check my answer again please
Hi, please check my work: In an experiment, 23.4 g of FES are added to excess oxygen and 16.5 g of FE2O3 are produced. The balanced equation is: 4FeS + 7O2 --> 2Fe2O3 + 4SO2 Calculate the % yield. My Answer: nFeS=23.4g/87.92 g/mol =0.266 mol 4mol FeS / 0.266 mol = 7mol O2/ ...
May 24, 2008

chem - CHECK PLEASE BOB PURSLEY
I MEAN ETHYLENE GLYCOL, SORRY.
May 24, 2008

chem - CHECK PLEASE BOB PURSLEY
not ethelyne glycol?
May 24, 2008

chem
what is the common name for ethane and propene? I think propene is propylene but i don't know about ethane.
May 24, 2008

gr. 12 chemistry
Hi, please check my work: In an experiment, 23.4 g of FES are added to excess oxygen and 16.5 g of FE2O3 are produced. The balanced equation is: 4FeS = 7O2 --> 2Fe2O3 + 2SO2 Calculate the % yield. My Answer: nFeS=23.4g/87.92 g/mol =0.266 mol 4mol FeS / 0.266 mol = 7mol O2/ ...
May 24, 2008

Chemistry - Bob Pursley
Posted by Sarah H on Friday, May 23, 2008 at 8:10pm. Hi, please check my work: In an experiment, 23.4 g of FES are added to excess oxygen and 16.5 g of FE2O3 are produced. The balanced equation is: 4FeS = 7O2 --> 2Fe2O3 + 2SO2 Calculate the % yield. My Answer: nFeS=23.4g/87...
May 24, 2008

Chemistry - please help
Hi, please check my work: In an experiment, 23.4 g of FES are added to excess oxygen and 16.5 g of FE2O3 are produced. The balanced equation is: 4FeS = 7O2 --> 2Fe2O3 + 2SO2 Calculate the % yield. My Answer: nFeS=23.4g/87.92 g/mol =0.266 mol 4mol FeS / 0.266 mol = 7mol O2/ ...
May 23, 2008

Chemistry - please help
Hi, please check my work: In an experiment, 23.4 g of FES are added to excess oxygen and 16.5 g of FE2O3 are produced. The balanced equation is: 4FeS = 7O2 --> 2Fe2O3 + 2SO2 Calculate the % yield. My Answer: nFeS=23.4g/87.92 g/mol =0.266 mol 4mol FeS / 0.266 mol = 7mol O2/ ...
May 23, 2008

chemistry-please check my work
Determine the mass of carbon monoxide that is produced when 45.6 g of methane CH4 react with 73.2 g of oxygen gas, O2. The products are CO and H2O. Please check my work: CH4 + 3O2 ---> 2CO + 2H20 nCH4=2.84 mol nO2=4.58 mol Limiting Reactant: 1 mol CH4/2.84 mol CH4 = 3 mol ...
May 23, 2008

chemistry - please help!
#1) how many atoms are represented by 2.0 mol of carbon? I think 12.01 x 10^23 #2) Calculate the # of atoms of each element present in 3.67 mol of H^2SO^4...I have no idea how to do this one?
May 22, 2008

Gen Chem
The signs of DG, DH, and DS at 25°C are shown in the table below for three reactions. Reaction DG DH DS I - + + II - - + III - - - Which reaction or reactions should go in the REVERSE direction at high temperature?
March 28, 2008

Gen Chem
That makes sense, just so I understand, how did you get 8.666 g Cr? What does the +6 to 0 mean?
March 28, 2008

Gen Chem
Chromium can be electroplated from an aqueous solution containing sulfuric acid and chromic acid, H2CrO4. What current is required to deposit chromium at a rate of 1.25 g/min? 1mol H2CrO4 has 51.996 grams current= coulomb/sec How do I convert to get coulombs from the problem?
March 28, 2008

Gen Chem
Consider the following reaction, A <===> B in a 1.00L container. At 1.77°C, the molar concentrations of A and B, respectively, 5.838M and 3.945M. Suddenly, 8.744 moles of A are added to the system. What is the change in DG of the system? Give the answer in kJ?
March 28, 2008

Gen Chem
A liquid is heated from 33.96°C to 104.32°C. The vapor pressure increases from 23.54torr to 984.35torr. What is the heat of vaporization of the liquid in kJ/mol? The change in temperature is 70.36°C. Change in vapor pressure = 960.76 torr. What is the equation to ...
March 28, 2008

Gen Chem
If Q=.61259, what is the formula to convert to pQ? Is it pQ=lnQ?
March 28, 2008

Gen Chem
n = 6 and E° = 0.011v for a redox reaction with Q = 7.03 x 10-1. Calculate E. Assume T = 298.15K. So I did E=E°-(RT/nF)lnQ Since the temp is 298.15, I substituted0.02569 for (RT/F) and got 0.011v-(0.0259/6)lnQ and got -.002355 Is that correct?
March 28, 2008

Gen Chem
Consider a cell based on the following reaction: GeO(s) + H2O(l) + 2 Ag+(aq) ===> GeO2(s) + 2 H+(aq) + 2 Ag(s) If [Ag+] = 1 M, at 25°C, would it be..... pH = 2 ( E° - E ) / 0.059159 V. or pH = ( E° - E ) / 0.059159 V.
March 28, 2008

Gen Chem
so n=10 then, right? 2Mn atoms (2*5), and 1*10 for the Cl...?
March 28, 2008

Gen Chem
So is n=5 then? (7-1)+(-1-0)? or (7-1)+(|-1-0|) then n=7? My choices are 2, 4, 5, 10, 16...
March 28, 2008

Gen Chem
What is n, the number of moles of electrons transferred, in the following reaction? 2 MnO4-(aq) + 16 H+(aq) + 10 Cl-(aq) ===> 2 Mn2+(aq) + 5 Cl2(g) + 8 H2O(l).
March 28, 2008

Gen Chem
How can I figure the equivalents of Cu deposited and then the number of coulombs?
March 28, 2008

Gen Chem
A current is passed through two cells connected in series. The half-reactions occurring at the cathode of each cell are TcO4-(aq) + 8 H+(aq) + 7 e- ===> Tc(s) + 4 H2O(l) and Cu2+(aq) + 2 e- ===> Cu(s). If 4.40 g of copper are deposited in the second cell, how much ...
March 28, 2008

Gen Chem
Neptunium-239 has a half-life of 2.35 days. How many days must elapse for a sample of 239-Np to decay to 1.00% of its original quantity? I got: close to 15 days. Is this right? I figured that about 1% of the original quantity would be roughly 6.5 Half lives, and since a half ...
March 28, 2008

Gen Chem
Consider the following reaction, A <===> B in a 1.00L container. At 1.77°C, the molar concentrations of A and B, respectively, 5.838M and 3.945M. Suddenly, 8.744 moles of A are added to the system. What is the change in DG of the system. Give the answer in kJ?
March 28, 2008

Gen Chem
n = 6 and E° = 0.011v for a redox reaction with Q = 7.03 x 10-1. Calculate E. Assume T = 298.15K. How do I set this equation up?
March 28, 2008

Gen Chem
It can be more than one of these choices, its a "check all that apply" question. Are there any other options that must apply for S=0??
March 28, 2008

Gen Chem
Which of the following conditions MUST be true for the entropy of a pure solid to be zero? a) T must be 0 K b) The solid must be crystalline and not amorphous c)the solid must be perfectly ordered d) the solid form must be an element
March 28, 2008

Gen Chem
Which provides the greatest increase in entropy for a mole of substance? a)Water melts at 0°C. b)Liquid water is heated from 0°C to 25°C. c)Gaseous water is converted to solid ice at 0.1°C. d)Water is converted from liquid to vapor at 100°C. e)Cannot be ...
March 28, 2008

Gen Chem
What is the number of nucleons in 236-U2+?
March 28, 2008

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