Friday
September 4, 2015

Posts by DrBob222


Total # Posts: 49,889

math, unit price
Answer moochers do it every time.
August 9, 2015

Govt.sen.sec.school darlaghat
Is your subject Govt.sen.sec.school.d; or is it chemistry? https://www.google.com/search?q=law+thermodynamics&ie=utf-8&oe=utf-8
August 9, 2015

chemistry
OK. I see I didn't do it the same way but you can also see that my numbers are the same. That 3.92 is the absorptivity constant and the 4.056 actually was 4.0565 but I just dropped the last 5. The book method uses ratio/proportion while I tried to reason it out from the ...
August 9, 2015

chemistry
You know, of course, that I have no idea how your book explains it, poorly or otherwise. Here is how you do it but I don't know it's the same method your book uses. Personally, when I was in grad school we did it all by graphing it. Makes a lot more sense to me. You ...
August 9, 2015

Math
Is 2-3-17 a three digit number?
August 9, 2015

Kaputian central elementary school
Is that 101?
August 9, 2015

Chemistry
KHP + NaOH ==> NaKP + H2O mols KHP = mols NaOH; therefore, you can use mL KHP x M KHP = mL NaOH x M NaOH There is no way this question can be answered without the concentration of the acid.
August 9, 2015

engineering math
Do you assume H2 is an ideal gas? (V1/T1) = (V2/T2) For V1 use ANY convenient number, say 100 mL. Then for V2 you use 105. T1 is 273; T2 will be in kelvin.
August 9, 2015

org chem
I answered this question for you last night and told you what pptn was and what crystallization was. If you don't understand those definitions or those processes you should repost and explain what you don't understand about each or both. Otherwise, your problem isn'...
August 9, 2015

science
You should clarify the question. As stated I can't make sense of it. Do you want to convert frequency to wavelength? If so then C = freq x wavelength c = 3E8 m/s freq = 1E12 or 200E12 Solve for wavelength By the way a kghz (or kGHz or kilogigaherz) is a THz or teraherz.
August 8, 2015

org chem
I can give you an example of this. You may own a Honda automobile and your neighbor may own a Rolls-Royce. Both are cars (automobiles) but technically they are not the same. A second example: You may have $999,000 dollars in your pocket. In real dollars (and life) you are rich...
August 8, 2015

org chem
Because technically means we are dotting all of the "i"s and crossing all of the "t"s. That's just another way of saying we are answering the question EXACTLY. So if you are answering the question exactly and the two processes are only similar, then it ...
August 8, 2015

org chem
No. The word "technically" bothers me. I think non-technically it may be similar but technically it isn't close. Precipitation is a reaction producing a solid; crystallization is not a reaction but a material coming out of solution where it has been dissolved.
August 8, 2015

Important question regarding chemistry
Look at the first and third pictures. The first is straight o-nitrophenol while the third one shows the H bonding. https://www.google.com/search?q=orthonitrophenol;&tbm=isch&tbo=u&source=univ&sa=X&ved=0CDQQsARqFQoTCIHhi-PomccCFYKPDQodCewOqQ&biw=1011&bih=601
August 8, 2015

Science
Here is how you do these. You can start with the topic you don't know and use as many of the steps as you need. http://www.chemteam.info/Redox/Redox.html I STRONGLY ADVISE YOU TO START BY PLACING A 2 AS A COEFFICIENT FOR HIO3 so that you are talking about electron loss/...
August 8, 2015

Chemistry
helloooo
August 7, 2015

Chemistry
I've copied this from above. And yes, in your example they are tripled and doubled because the power of each is 1. So 3^1 is 3 and 2^1 is 2. Right? So the 3^1 comes because of your tipled/doubled part and the 2^1 comes from your tripled/doubled part. And the 3 in the O3 ...
August 7, 2015

Chemistry
I made a typo in that response and that may have confused you. However, after starting that sentence with 'Now if it were a second ....." I never tripled anything. I doubled CO2 and doubled O3. i SHOULD have written, if the equation were rate = k(CO2)^2(O3)^3. Then ...
August 7, 2015

Chemistry
I think the answer to all of your questin is yes. If you double the pressure then the volume is halved and the concentration is doubled. Right? So just figures p and c are the same for this. And yes, in your example they are tripled and doubled because the power of each is 1. ...
August 7, 2015

Chemistry
For a first order reaction rate = k*(concentration)^1 k is a constant. Your question asks for the expression, not for an answer numerically. They don't give a k and they don't list a concentration. k can be determined from k = 0.693/t1/2 and you can evaluate that by ...
August 7, 2015

Chemistry
rate = k(Sr-90)
August 7, 2015

Chemistry
The problem asks for grams so I think you should make that conversion if you want to answer the question. For how you do it go back and read my response. I told you how to do it. Also you should punch those numbers into your calculator again. I didn't get that number. Also...
August 7, 2015

Chemistry
Do you mean propEne? Do you mean k = 6.22E-4 s^-1? rate = k*0.03 = mols/L*s Then mols/L*s x (60 s/min) x 10 min x 2.5 L = mols in 2.5L in 10 min. Convert to grams. mols = grams/molar mass. You know molar mass and mols, solve for grams.
August 7, 2015

Chemistry
I did this but first you know it can't be A and it can't be D. B and C are the only possibilities and I did that by ..1.0...........0......0.......0 min 0.87...........0.13...0.13.....100 min 0.74...........0.26...0.26.....200 min 0.61...........0.39...0.39.....300 min...
August 7, 2015

chemistry
I think the secret word here is "estimate". I see that the temperature is changing by 10 degrees. There is an estimate in reaction rates that a reaction doubles for every 10 degrees change. So 2 x 12 mL = ?
August 6, 2015

Math
Sorry Ms. Sue, I thought you may have called it a night.
August 6, 2015

Math
Since this is simple interest, convert 22 months to years (rate is 8.5%/yr I assume) so 22/12. I = 46945*0.085*(22/12)=? Then final value is 46,945 + I.
August 6, 2015

chemistry
mols (NH4)2SO4 = grams/molar mass = ? Then m = mols/kg solvent.
August 6, 2015

Chemistry
I hardly know what you're clarifying. The rate law, since both NO and O3 are raised to the first power should b e doubled and tripled.
August 6, 2015

Logical Reasoning
What's the question?
August 6, 2015

Opra college
2KClO3 ==> 2KCl + 3O2 mols KClO3 = grams/molar mass = ? Using the coefficients in the balanced equation, convert mols KClO3 to mols O2. Then mols O2 x 22.4L = L O2 at STP
August 6, 2015

Chemistry
I think standard conditions in this case means 25 C and 1 atm and ALL will have those conditions. What counts is dH and dS where dHrxn = (n*dHf products) = (n*dHf reactants) and dSrxn = (n*dSf products) - (n*dSf reatants) or dGrxn = (n*dGf products) - (n*dGf reactants)
August 6, 2015

Chemistry
Frankly, I think there is insufficient information for all of them. You need delta G. In a general sense exothermic reactions (delta H is -) often are spontaneous unless delta S screws things up and endothermic reactions (delta H is +) unless delta S screws things up. ...
August 6, 2015

DPS sub: science ( chemistry)
S won't do it since it isn't soluble in water. (C and Si are not soluble either). The answer is sodium. 2Na + 2H2O ==> H2 + 2NaOH and NaOH is a strong base which will turn phenolphthalein pink.
August 6, 2015

chemistry
HBr + NaOH ==> NaBr + H2O Since HBr is a strong acid and NaOH is a strong base, the material at the end is just a salt in water. The pH of the water will be 7 (at least that's the simple answer and it neglects ionic strength and the Debye-Hueckel theory).
August 6, 2015

Chemistry
What is glacial acid. Do you mean glacial acetic acid.
August 6, 2015

chemistry
You can easily pick up cellulose (paper) fibers from the filter paper and that contaminates the material before you take the melting point.
August 6, 2015

Chemistry
I don't know what your instructions are. One answer is all that you have given; i.e., T, dH and dS because you can calculate dG from those three. If I had a choice I would choose dG.
August 5, 2015

Chemistry
You need dG. If you don't have that, you can calculate it from dG = dH - TdS
August 5, 2015

Chemistry(Titration)
Back titration with what? Probably because MO indicator changes color approximately 4 while phenolphthalein changes color approximately 8.3. If you are titrating CO3^2- with acid, using phenolphthalein the end point is not as sharp AND it titrates only 1 H^+ while the MO is a ...
August 5, 2015

Enthalpy Change Calculations
Yes but I don't understand why you did all of that work. dH = (n*dHf products) - (n*dHf reactants) dH = (1*-242 kJ) - (1*-286 kJ) dH = -242-(-286) = 44 kJ. Since dH is +, the reaction is endothermic. I looked up the Hof in a set of tables.
August 5, 2015

Logical Reasoning
D. It COULD be locked to the post but why couldn't it be in the garage also so I don't think D is correct? What about E? Since ALL of the bikes in the shed are red, (and Lynn's bike is green) aren't you quite certain it isn't in the shed?
August 5, 2015

Algebra
Rodney is 1 mi/1 hr = 1 mph Patrick is 1 mi/1.5 hr = 0.67 mph 1-0.67 = 0.33 mph faster
August 5, 2015

college. physics and chemistry and mathematics
a = 4r/(2)^1/2 a = 4*200/1.414 = ?
August 5, 2015

chemistry
A. pH = pKa + log (base)/(acid) Convert 26.56 g NaAc to mols, convert to M, plug into the above equation and solve for pH. B. I like to work these by millimols (mmol) and not M. mmols HAc = 250 x 1.56 = about 400 but you need a more accurate number. mmols NaAc = 26.56/82 x ...
August 5, 2015

Chemistry
Yes and no. I have copied the problem below and added my comments in bold. Balance the equation CuSO4 + Pb(NO3)2 → PbSO4 + Cu(NO3)2 Find the number of moles for CuSO4 c=n/v n=c × v n=0.2 × 0.01 n=0.002 mol Since it is a 1:1 ratio, the number of moles for Pb(...
August 5, 2015

Chemistry
I assume principle means that there may be intermediate reactions but what is shown is the overall reaction. I agree with you that delta S probably is negative and for the reason you cite. You don't mention the water but that is a liquid and S is lower for liquids than ...
August 4, 2015

college chemistry
Enrique is correct but just for the record this is how I did it. 7600 ft^3 x (1,728 in^3/ft^3) x (2.54 cm/in)^3 x (1 L/1000 cc) = ? 1,728 and 2.54 and 1000cc to 1L are just three of those conversion factors I memorized back in the days before calculators, computers, and such ...
August 4, 2015

college chemistry
Sara, sam, et al. Why not use the same screen name? volume room is 950 ft^2 x 8 ft = ? cubic feet. Convert to L. You have 53 atoms Rn222/L so 53 atoms/L x #L = # Rn222 atoms in the basement. B. Convert # atoms Rn to mols Rn and use PV = nRT to solve for P.
August 4, 2015

college chemistry
It is easier to help you if you use the same screen name. You don't list the half life but step 1 is to determine k. That is k = 0.693/t1/2 Then ln(No/N) - kt No = 100 N = 64.3 k from above Solve for t I used 100 and 64.3; you can use ANY number for No, then N is No*0.643
August 4, 2015

Lccn
You're typing gibberish. Make sense out of this or quit wasting our time. Type your question if you have one.
August 4, 2015

Lccn
I have no idea what RMNO4 is.
August 4, 2015

Lccn shool
mg means nothing. I assume you mean Mg. Mg + 2H2O ==> H2 + Mg(OH)2
August 4, 2015

Lccn shool
What do you want. products are KCl and H2O BUT that is assuming you mean HCl and KOH. Use your caps key correctly. Proof what you write before posting.
August 4, 2015

Chemistry
I don't believe you have posted the entire question; however, what you have is correct so far. Personally, I would have used 4.184 for the specific heat. Most of these questions ask for the heat/mol; you have calculated the heat of the reaction as shown.
August 4, 2015

URGENT CHEMISTRY
Why do I want to do all of your home work? What don't you understand about this? It's products divided by reactants with coefficients for each material becoming the exponent for that material. For example, f is K = (SO3)^2/(SO2)^2(O2)
August 4, 2015

Chemistry
Your two equations are not balanced and we can't do anything with them until they are. For example, #1. You have 2A on the left and 2A on the right. You have 2/3 C2 which is 4/3 C on the left but 3 on the right. Are you sure that isn't 2A + 3/2 C2 = A2C3? And #2 would ...
August 4, 2015

Chemistry
I don't think you read my response. Re-read. mols C = grams/atomic mass C.
August 3, 2015

Chemistry
If that is all that's confusing you the easiest way to take care of it is that you don't start with 5.00 kg but 5.00 kg x 0.962 = ? kg and I would change that to grams. mols C = grams/atomic mass C = ? Then 395 kJ/mol x # mols = ? kJ released. Personally I don't ...
August 3, 2015

chemistry
See your earlier post below.
August 3, 2015

Chemistry
q = mass H2O x heat fusion You know mass H2O in grams, look up the heat fusion in J/g and solve for q in joules. The problem actually is not complete because it doesn't tell you the temperature of the water being sprayed. I think it assumes you will assume the temperature ...
August 3, 2015

chemistry
I have looked under reactions of azomethine, reaction of 4-aminotoluene and vanillin, reaction or p-aminotoluen and vanillin, and other variations and came up with nothing. You might have better luck trying some variation of those on Google. Sorry about that. I did find these ...
August 3, 2015

chemistry
You want me to write up your experiment. No thanks.
August 3, 2015

Chemistry
You may be overwhelmed with information that is not needed. You don't care what it's being used for nor even what it is. All you need to do is to convert kJ to calories. There are 4.184 J in 1 calorie and 1000 J in 1 kJ. So 1367 kJ x (1000 J/1 kJ) x (4.184 J/cal) = ? ...
August 3, 2015

Urgent chemistry
Something is missing here. You saw that answer from Sarah and I explained that part. What do you not understand about this? All you need to do is reason out the law. In fact I answered what P will do (both increase and decrease). I explained about adding NH3. Why won't the...
August 3, 2015

Chemistry
2 is C for sure. #1 is not that easy I don't think. The question asks about total energy but provides only the fact it is endothermic. Endothermic tells you that the reaction absorbs heat from the surroundings in order to occur. It doesn't say anything about the total ...
August 3, 2015

Chemistry
If you are having a problem balancing these you need to tell us what the problem is. All appear to be balanced to me.
August 3, 2015

Chemistry
That's right. Increasing P shifts to the side with fewer mols OF GAS. There are 4 mols on the left and 2 on the right so increasing P shifts to the right; decreasing P shifts it to the left.
August 3, 2015

Chemistry
In common words, Le Chatelier's Principle tells us that when a system in equilibrium is subjected to a stress, it will shift to undo what we did to it. So look at the equation. 3 H2(g) + N2(g) <- -> 2NH3(g) + heat Adding NH3. So the reaction will try to use up NH3 to...
August 3, 2015

Chemistry
See your other post.
August 3, 2015

Equilibrium
In the problem, yes. In real day to day work, you must know the temperature for which the K is given because K is different at some other temperature.
August 3, 2015

Equilibrium
You work this EXACTLY as you did for the previous problem. The 852 never enters into it EXCEPT that the Keq you calculate will be good ONLY for that temperature.
August 3, 2015

Chemistry
Which oxide? Any one of the several that are known? I will assume NO. Note the following: For H2O. (0.126g H2/2 H atoms) x 16 = 1.00 g oxygen and (0.216g H2/3 H atoms) x 14 = 1.00 g N, so (1.00/14) x 16 = ? g N to form NO.
August 3, 2015

Chemistry
See your post above.
August 3, 2015

org chem
If you are talking about a NON-VOLATILE SOLUTE you are right. It may or may not be true with a volatile solute and volatile solvent. When a non-volatile solute dissolves in a volatile solvent, three things happen. a. The vapor pressure of the solvent is lowered, b. The boiling...
August 2, 2015

org chem
The partition constant, also called the distribution constant, is a number, similar to Ksp and Keq that defines the solubility of a solute between two immiscible solvents such as water and hexane.
August 2, 2015

Chemistry
Ba(OH)2 + 2HCl ==> 2H2O + BaCl2 mols Ba(OH)2 = M x L = ? mols HCl = M x L = ? which is twice that of Ba(OH)2 so the two exactly neutralize each other. q = heat generated = mass H2O x specific heat H2O x (Tfinal-Tinitial) mass H2O = 65 + 65 = 130 mL = 130 g specific heat H2O...
August 2, 2015

org chem
Great. Glad to help. You must be careful about "bunching up" ethyl, propyl, butyl groups. When you do that you forget about counting the carbons in those bunched up groups to make the longest chain--so you end up getting smaller chains than you would do otherwise.
August 2, 2015

org chem
Draw it out--which I can't do on this forum. Then count the LONGEST chain. It will be a hexane so it will be named as a 3-methylhexane.
August 2, 2015

chemistry
Are you talking about 20% w/w/ or 20% w/v? I will assume you mean 20% w/w which means 20 g ethylene gycol in 100 g solution. So that is 20 g ethylene glycol in 80 g H2O. n H2O = g/molar mass = ? n ethylene glycol = grams/molar mass = ? total mols = n H2O + n ethylene gycol ...
August 2, 2015

science
Your question makes no sense.
August 1, 2015

chem
% w/v = (grams solute/mL solution)*100 =
August 1, 2015

Chemistry
Anonymous points out that you don't have an equation; however you can use an ionic equation of 2Ag+ + CrO4^2- ==> Ag2CrO4 Assuming you have enough chromate to use all of the AgNO3, you can produce 6 mols AgNO3 x (1 mol Ag2CrO4/2 mols AgNO3) = ? 2AgNO3 + Na2CrO4 ==> ...
August 1, 2015

Chemistry
I couldn't have said it better.
August 1, 2015

chemistry
Probably you want to know the (H^+). mols of the 3M HNO3 = M x L = ? mols of the 4M HNO3 = M x L = ? M of the mixture is M = total mols/total L If you want to know the pH it is pH = -log(HNO3)
August 1, 2015

Organic chemiststry
As my organic prof used to say, "To the general public there are three kinds of alcohol; the kind you drink (ethyl alcohol), the kind you drink and go blind (wood or methyl alcohol) and the kind you rub on your back (rubbing alcohol or isopropyl alcohol)." The point ...
August 1, 2015

Organic chemistry
See your other post.
August 1, 2015

Chemistry
HF<HCl<HBr<HI<HClO4 HF is the weakest; HClO4 the strongest.
August 1, 2015

chemistry
The H on the right hand side of HCOOH is the active H (as in HCl etc) and from there it's a usual acid/carbonate reaction. HCOOH + CaCO3 ==> Ca(HCOO)2 + H2O + CO2 You balance.
July 31, 2015

College Algebra
Isn't this just a matter of punching the numbers into your calculator?
July 31, 2015

Emergency chemistry
I see only two questions you posted and I responded to them almost an hour ago.
July 30, 2015

Science
http://www.jiskha.com/display.cgi?id=1438290333
July 30, 2015

Science
You posted this yesterday and received a reply. Why are you post again?
July 30, 2015

chemistr
The beginning energy, the ending energy, the difference between beginning and end.
July 30, 2015

Chemistry
Solids don't enter into the equilibrium constant expression; therefore, ignoring those the expression is Keq = (BO2) Since the (BO2) at equilibrium is given as 2.0 M in the problem, then K must be .....?
July 30, 2015

Chemistry :(
Le Chatelier's Principle tells us that if we do something to affect the equilibrium of a reaction, it will try to undo what we did to it. I would rewrite the equation as 3H2(g) + N2(g) ==> 2NH3(g) + heat Adding a catalyst NEVER changes the equilibrium although it ...
July 30, 2015

Chemistry
See your other post.
July 30, 2015

chemistry
Surely you don't mean 0.01 g/mL density. I might believe 1.01. Steps to follow after you know the density. mass solution = 1000 mL x density = ? mass solution - 10 g H2SO4 = ? g H2O Then mols H2SO4 = 10/molar mass = ? mols H2O = grams/molar mass = ? XH2SO4 = mols H2SO4/...
July 30, 2015

Chem
I'm not sure what you want when you say describe. Heat will flow from the 59 C metal to the 25 C water. The metal will cool; the H2O will warm. The final T of both will be less then 59 and greater than 25 You can calculate the final T of both by substituting and solving ...
July 30, 2015

Physical sciences
You need to provide more details. This seems to just part of the problem.
July 30, 2015

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