Number of results: 390
DrBob222 please check
DrBob222 please check my physics question posted at 8:55pm. The subject is drwl please check. I am not getting a response from drwl. Thanks! Mary DrWLS is not on right now. My physics is too poor to trust my answers. Bob Pursley is smarter than I am; he does physics, math, and...
February 27, 2007 by Mary
Drbob222, even if you just tell me that there is an answer to the following problem then i know that there is an answer because i've tried many ways and i can't get x alone. -4(2x-3) = -8x +5 Is there an actual answer for this one? No. There is no answer, the question is ...
December 19, 2006 by jasmine20
solve Ka for HX => H^+ + X^- given 0.1M LiX at pH=8.9 Chemistry - DrBob222, Tuesday, March 30, 2010 at 6:32pm LiX(aq) ==> Li^+(aq) + X^-(aq) X^- is a base and hydrolyzes in water to X^- + HOH ==> HX + OH^- Make an ICE chart and substitute into the following: Kb = (Kw...
March 30, 2010 by Larry
I'm sorry the problems i posted had a couple of errors how i posted it here they are: Posted by DrBob222 on Friday, November 24, 2006 at 6:19pm in response to Math. Thanks for showing your work. It helps us to know where you are having trouble. #4. [25/ (2^3-3)]*2 the star two...
November 25, 2006 by Jasmine20
chem- drbob222 please help
my original question was: how do i figure this out?? How much heat does your body lose when 2.46 g of sweat evaporates from your skin at 25°C? chem - DrBob222, Tuesday, February 22, 2011 at 10:52pm q = mass water x delta Hvaporization. chem - Rebekah, Wednesday, February 23, ...
February 23, 2011 by Rebekah
solve Ka for HX => H^+ + X^- given 0.1M LiX at pH=8.9 Chemistry - DrBob222, Tuesday, March 30, 2010 at 6:32pm LiX(aq) ==> Li^+(aq) + X^-(aq) Question for DrBob222 - is the X^- value in the ICE calculations 0.1 from the initial LiX 0.1M? X^- is a base and hydrolyzes in ...
March 30, 2010 by Larry
Calculate the pH of an aqueous solution of 0.15 M potassium carbonate. I know that pH = -log(H30+) but I am not sure how to start this problem. Chemistry(Please help) - DrBob222, Saturday, April 14, 2012 at 11:09pm Hydrolyze the CO3^2-. CO3^- + HOH ==> HCO3^- + OH^- Do an ...
April 18, 2012 by Hannah
DrBob222, I don't know how to solve this problem either. And yes, this is the question for this problem. I even double check it. Please help. Chloroform (CHCL3) has a normal boiling point of 61 'C and an enthalpy of vaporization of 29.24 kJ/mol. What is the value of delta Gvap...
April 30, 2013 by Chloe
so i posted this question yesturday and got some help. which is the stuff below. can you look at the last thing i said which was the answer i got by doing what DrBob222 said to do and tell me if its correct.(the question is the first section) thanks chem - hannah, A salt ...
November 10, 2010 by hannah
Strychnine, C21H22N2)2(aq) is a weak base but a powerful poison. Calculate the pH of a 0.001 mol/L solution of strychnine. The Kb of strychnine is 1.0 x 10^-6 DrBob222, I am planning on obtaining a pHD in about nine years:P Can you give me some advice on how to be that 1% of ...
April 6, 2008 by Sarah
Chemistry(Please help, thank you)
I have to calculate the concentration of I2 produced (# of moles of I2 produced / L) based on the stoichiometric ratio in the following equation. 2S2O3^2- + I2 -> 2I^- + S4O6^2- Chemistry(Urgent, please help) - DrBob222, Sunday, February 26, 2012 at 9:47pm If you know the ...
February 27, 2012 by Hannah
DrBob222 I am beginning to understand about balancing equations well, thanks to your help, but there are still some other things, which I am having a hard time figuring out. Complete and balance the following chemical reactions between an acid and a metal. A) HBR + Mg -> ...
July 13, 2010 by Derrick
Convert a pressure of 23.8 in. Hg into kilopascal. Ok so I looked up kilopascal and it Said 1 Kpa = 1000 pa So I began to set it up like this 23.8 / 29.2 x1000 am I correct Chemistry - DrBob222, Thursday, October 13, 2011 at 1:48pm I don't think that will get it. I would go ...
October 13, 2011 by Monique
Hi Dr. Bob would you please tell me what D rpresents? Thank you! What is the reactant, products, and what compounds is it? Is it H2O, O2, or what? What are the transition molecules? Help please. Do as below to get to the image. I couldn't put the URL in and it isn't my website...
June 17, 2012 by Anonymous
I know I posted this but you didn't answer! Please help!!!! Consider the following reaction at 298 K: C(graphite) +2Cl2 (g) -----> CCl4(l) Calculate the following quantities. Delta H: -139 kJ/mol deltaS(sys)=? J/mol*K deltaS(surr)=? J/mol*K deltaS(univ)=? J/mol*K My answer ...
March 15, 2012 by Kelsey
The following thermodynamic data was obtained for an unknown compound. Delta Hvap = 31.3 kj/mol and Delta S Vap= 79.7 kj/mol .Calculate the normal boiling point of this compound in Celcius.. Thank you! Chemistry - DrBob222, Tuesday, April 30, 2013 at 12:31am dG = dHvap - ...
April 30, 2013 by Chloe
Can you check my previous postage I'd reply already. Thank you done below What are about the other messages are they okay too. I think I just finished with all of them.
December 11, 2006 by Jasmine20
Calculate the standard free-energy change for the following reaction at 25 C degrees. 2Au^3+(aq)+3Ni(s) <-- --> 2Au(s)+3Ni^2+(aq) Ni2+(aq) + 2e- -> Ni(s) E=-0.26 Au3+(aq) + 3e- -> Au(s) E=+1.498 G= ? KJ Would it be G=1.758? •Chemistry - DrBob222, Sunday, March 31, ...
April 1, 2013 by Anon
A student fails to fill the cuvette 2/3 full with the reaction mixture ( CV+ and OH-). What effect does this error have on the measured absorbance values? Thank you :)
October 9, 2013 by K
DrBob222 - can you set up the equation for the volume problem, i don't have a clue... Is this Charles Law? I know how to change C to K you add 273, but I don't know what figures go where in this formula PV=nRT......
April 18, 2010 by Tracey
For Bobpursley Chemistry
I already asked Drbob222 for a substance that i cantake to school wich contains an aromatic compund, I'm not suppose to buy because it must be at home. please help me:0
January 31, 2007 by Iveth
A .326L container holds 0.146g of Ne and an unknown amount of Ar at 30C and the total pressure is 627 mmHg. Calculate the moles of Ar present? (I have calculated temp 308K, pressure is 0.825 atm and moles of Ne are .007) Chem - DrBob222, Wednesday, March 3, 2010 at 3:25pm T ...
March 4, 2010 by Staci
A certain compound contains carbon, hydrogen , and oxygen. When 1.00 grams of this compound are burned in oxygen gas 1.47 grams of CO2 and 0.600 grams of water are formed. When 2.75 grams of the compound are dissolved in 10.0 grams of water the resulting solution freezes at –2...
January 17, 2011 by Patrick
Can you please check my previous science post. As of right now, you are the only science teacher on this site--which is why I am pleading you to. Thank you very much:-)
April 8, 2010 by Sara
TO DrBob222 or any science helper
identify the following formulas as acids, bases or salts: HCH3COO NaCL H2CO3 C6H8)7 Mg(OH) NaOH KBr Sr(OH)2 HNO3 please help really urgent :) thanks :)
March 12, 2014 by Anonymous
Science - BTUs Please help
Although I vaguely see DrBob222's concept, I still need some help in the set up. Thank you. A 10 lb. frozen boneless roast needs to be thawed and baked to a temperature of 200 degrees F. The storage freezer maintains a temperature of -10 degrees F. Pork changes from solid to a...
September 3, 2012 by Sejul
DrBob222 PLEASE HELP!
I posted this question already but you never replied back :( Consider the following reaction at 298 K: C(graphite) +2Cl2 (g) -----> CCl4(l) Calculate the following quantities. Delta H: -139 kJ/mol deltaS(sys)=? J/mol*K deltaS(surr)=? J/mol*K deltaS(univ)=? J/mol*K My answer...
March 17, 2012 by Leila
Hi I have a follow up to a question that was answered previously. New question: So when the HPO4(2-) reacts with the NaOH, will the equation be this?: HPO4^(2-) + NaOH --> H2O + NaPO4(2-) But how do I write the equation for the H2PO4^- and HCl? H2PO4^- + HCl --> Here is ...
January 30, 2012 by jean
1) The Ka for acetic acid is 1.8e-5. What is the pH of a 3.18M solution of this acid? I did 1.8e-5 = x^2/3.18 x=sqrt 1.8e-5 X 3.18 = 7.56e-3 pH=-log(7.56e-3) = 2.12 The pH is 2.12 2) At 25 degrees celsius, the pH of a 1.75M NaCN solution (the Ka for HCN is 4.0e-10) is ? 4.0e-...
April 2, 2012 by Hannah
chemistry grade 12
Thanks DrBob222 for previous answers. Question: Balance the following reactions by the oxidation number method. a) I2 + HNO3 --> HIO3 + NO2 + H2O b) MnO4- + H+ + Cl- --> Mn2+ + Cl2 + H2O
November 17, 2009 by Ron
Posted by Jamie on Sunday, June 20, 2010 at 3:36pm. You are given three test tubes that contain colourless liquid. One test tube contains benzene, another contains ethanol, and the third contains 2,4-hexadiene. Design a procedure that will tell you the contents of each test ...
June 20, 2010 by Jamie
thanks but i do need help to solve the third part also, I did get these equations but don't know how to put them together to solve the third. thanks for helping further!
October 29, 2007 by Gavin
DrBOB222 pertaining to the MATH question
i got p to be 11 but i do not know how to solve the equation 6x^3 - 11x^2 - 14x + 24=0 Now, you know one root is x=2, so that is a factor. Divide x-2 into the polynomial. That will give you a binomial, which will give the other two factors.
December 9, 2006 by KIM
What is the pH of a 5.06E-2 M aqueous solution of sodium acetate? I know that I would set this up the same way I did for the previous question that I posted. I am just confused on how to find the Ka. I know it is kw/kb but for what compound is what I do not know. Chemistry(...
April 8, 2012 by Hannah
BTW I just want a yes, no, and/or hint for these questions to save some time. True/False Doubling the amplitude of a wave will double the amount of energy the wave can transfer. True
April 5, 2008 by Jon
College Chemistry (DrBob222)
Use the Nernst equation to calculate the iron (II) concentration for the following iron/copper electrochemical cell when [Cu2+] = 0.012 M and Ecell = 0.750 V at 35°C. Cu2+ (aq) + Fe (s) --> Cu (s) + Fe2+ (aq)
April 6, 2014 by Adrik
Calculate the molar solubility of MgCO3 in a solution that already contains 1.7×10−3 M sodium carbonate. MgCO3 Ksp = 6.82 x 10-6 IMPORTANT NOTE: You must use the quadratic equation to solve this problem. (DrBob222- thank you so much for all your help!)
April 26, 2013 by Chloe
What would the pH value for grapefruit juice be? >7, 7, <7 It wouldn't be 7 because its not neutral, it wouldn't be greater than 7 because that's considered to be basic, I think it would be less than seven because it has acid in it. So it would be <7?
October 12, 2010 by Anonymous
2N2O(g) → 2N2(g) + O2(g) d[N2O]/dt = -5.8×10-4 M/s at a particular temperature and set of concentrations. What are d[O2]/dt and d[N2]/dt? d[O2]/dt = d[N2]/dt = What is the rate of the reaction? my answer for the first one im getting -.00016 and the second one 2.9e-4 and ...
September 29, 2010 by Jane
0.2g of an organic sample W, analysed by combustion analysis results in 0.48g of CO2 and 0.1636g of H2O. We had a second sample 0.2g of W again producing 0.0618g of ammonia. Show that only C, H and N exist in W and find its emperical formula.
November 30, 2013 by michelle
what is the concentration of hydrogen ion in a 0.1M solution of sodium hydroxide(NaOH)? NaOH dissolves and completely dissociates in H2O to form the ions. NaOH ==> Na^+ + OH^- Therefore, starting with 0.1 M NaOH will give you 0.1 M in Na^+ and 0.1 M in OH^-. You know Kw=(H...
December 31, 2006 by michelle
Chemistry -- DrBob222
A gas initially at STP is heated to 50°C keeping the volume constant. What is its new pressure? I used this formula: P1 = 1 atm T1 = 273 K T2 = 323 K solve for P2 P2 = P1 (T2/T1) But, where do I use the 50 degrees C? Also, is my answer correct: P2 = 1atm x 323K/273K = 1.18 atm
May 24, 2013 by Timofey
Chemistry - DrBob222
C6H14 + Cl2 in UV light Below are 5 products, say which one cannot be a product, prove this by showing how each of the other products were formed from the equation above. 1-chlorohexane 2-chlorohexane 2,2-dichlorohexane dodecane hex-1-ene
February 11, 2014 by Ava
College Chemistry (DrBob222)
The decomposition of HCO2H follows first-order kinetics. HCO2H(g) CO2(g) + H2(g) The half-life for the reaction at a certain temperature is 44 seconds. How many seconds are needed for the formic acid concentration to decrease by 73%?
April 16, 2014 by Ana