# Posts by DrBob222

Total # Posts: 55,716

Dont need to answer if you dont want to
All of the people who "work here" are volunteers. Many, but not all, are retired teachers. No one has a schedule. Ms Sue is so talented that she can answer questions on many subjects, while others, like me, answers questions on chemistry but not much else. Now and ...

Chemistry - Liquid Methane?
That answer looks OK to me. You can also note that He, H2, N2, O2, Cl2 etc etc are non-polar and all of them can be a liquid if the T is low enough (high pressure helps too). He is a tough one to get but it's down there almost at absolute zero.

Chemistry
Personally I think the question is a poor one. I think your answer is good for that type question AND I think your first answer is good also and your reasoning that something else is needed is right on. Another way is to say that molecules in solids are not easily displced but...

Chemistry
let's do this one step at a time. 1. Write and balance the equation. You've done that. 2Na + 2H2O = 2NaOH + H2 2. Convert g Na to mols. You've done that. 48.7/22.99 = 2.12 mols. 3. Now you want to convert mols Na (what you have)to mols H2(what you want). You do ...

oops typo
I've reposted and corrected the three typos. If you have an s electron, l = 0 If you have a p electron, l = 1 If you have a d electron, l = 2 There are 5 d orbitals. I suspect you counted the 5d orbitals as well as the 5p(three of those) and the 5s(1 of that) for 5+3+1 = 9.

Chem-Bob Pursley
I'm not Bob Pursley but will I do. If you have an s electron, l = 0 If you have a p electron, l - 1 If you have a d electron, l = 2 There are 5 d orbitals. I suspect you counted the 5d orbitals as well as the 5p(three of those) and the 5s(1 of that) for 6+3|1 = 9.

chemistry
Acetic acid = CH3COOH = HAc Zn + 2HAc ==> Zn(Ac)2 + H2 This is a single replacement reaction. Do you see why? The Zn replaces the H.Te H is the single atom replaced.

Chemistry
Bob Pursley answered this for you earlier in the day.

chemistry

Science
diamonds

Chem help
Tbe ONLY time the value of Kc changes is with temperature.

Chemistry
Of course not. The atomic number is 33 according to the problem.

Chemistry
mass mi,ber = #protons + #neutrons Remember # protons is the atomic number.

Chemistry
You made an error; it's Na2SO4. 2Na^+(aq) + SO4^2-(aq) + Ba^2+(aq) + 2NO3^-(aq) ==> BaSO4(s) + 2Na^+(aq) + 2NO3^-(aq) I have written the complete ionic equation above. To make it into a net ionic equation, cancel those ions that appear on both sides. The net ionic ...

chemistry
# electrons = 6

Chemistry Basic
Remember the Law of Conservation of Mass. What you start with on the left must equal what you end uyp with on the right. 2Li + F2 ==> 2LiF 1.00. +x = 3.73 so what's x?

Chemistry
You reposted you're same request; didn't you ready my 1:40 am response. I did what you wanted AND in GREAT detail. I worked what you wanted step by step. Did I do all that work for nothing? I made a typo eight lines up from bottom line. It should read "which is 1 ...

Chemistry
7.2E-9 = (s)(2s+0.004)^2 Assume 2s + 0.004 = 0.004, then 7.2E-9 = (s)(0.004)^2 s = 7.2E-9/(0.004)(0.004) = 4.5E-4 mols/L. For keeping 2s+0.004 as is I did this. 7.2E-9 = (s)(2s+0.004)^2. First, I expanded the (2s+0.004)^2 to get 4s^2 + 0.016s + 1.6E-5 and that times s gives 4s...

Chemistry
You made a few errors at the beginning due to carelessness. This is a common ion problem (the common ion is I^-) and the addition of a common ion always decreases the solubility from what it would be in a pure water solution. Here's the scoop. ........PbI2 ==> Pb^2+ + ...

Chemistry
Did you really want to calculate the solubility of PbCl2 or did you mean to calculate the solubility of PbI2 in a KI solution? I suspect the latter. I........solid.....0.......0 C........solid.....x.......x E........solid.....x.......x

Chemistry
See your previous post. This problem is the same kind. Only the numbers are different.

Chemistry
You want to calculate Qsp and compare with Ksp. ..........CaSO4 ==> Ca^2+ + SO4^2- Qsp has the same format as Ksp; i.e., Qsp = (Ca^2+)(SO4^2-). Substitute the following. (Ca^2+) = 2E3M x 40/100 = ? (Note: I wonder if you meant 2.0E-3??? (SO4^2-)= 3.0E-2 x 60/100 = ? ...

Chemistry
The internet lists density of KCl as 1.98 g/cc. nass single molecule = molar mass/6.022E23 = ? There are 4 molecules to the unit cell; therefore, mass unit cell is 4*mass single molecule. Colume = (edge length)^3 Finally, density = mass unit cell/volume unit cell = ?

My 2 cents worth. One goes to school to learn to do think for themselves, solve problem by themselves, and live for themselves. Copying answers from another doesn't help you do any of those things. You may pass the course by getting answers from others but will they always...

oops--slipped sign--Chemistry
I added those together but put a - sign. Arrrgh!. The following corrects that. (mass metal x specific heat metal x (Tf-Ti) + (mass ice x heat fusion ice) = 0

Chemistry
heat lost by metal is mass metal x specific heat x (Tfinal-Tinitial). Tf = 0; Ti = 187 heat gained by ice is mass ice x heat fusion. I used 333.5 J/g for heat fusion Put those together. (mass metal x specific heat metal x (Tf-Ti) - (mass ice x heat fusion ice) = 0 Solve for ...

Chemistry
The diluted solution is 3.00 x (10/250( = approx 0.12M. mols KOH taken for titration will be 0.12M x 0.0385 L = o.00462 KOH Convert mols KOH to mols H3PO4 using the coefficients in the balanced titration equation. This problem is worded poorly. It is worded to make one think ...

CHEMISTRY
So you understand the theory behind this. BaSO4 ==> Ba^2+ + SO4^2- Le Chatelier's Principle says that when we do something to a reaction at equilibrium the reaction will shift so as to undo what we did. SO, if we add (NH4)2SO4 to the reaction, that's adding SO4^2-. ...

General Chemistry
I obtained that number also.

General Chemistry
Except for some rounding differences I get the same thing. I get 3.23E-4 mols

General Chemistry
You should be able to ue PV = nRT and solve for n. Essy enough. Then rate is= delta(N2)/delta Time) Remember for (N2), that is mols/L. You will have mols and L.

chemistry
LiH + H2O ==> LiOH + H2 CaH2 + 2H2O ==> Ca(OH)2 + 2H2 You must write two equations and solve them simultaneously. NOTE; ALL OF THESE NUMBERS ARE ESTIMATES; YOU SHOULD RECALCULATE ALL OF THEM. Let Y stand for grams LiH. and Z stand for grams CaH2. Then equation 1 is Y + Z...

Chemistry
........HA ==> H^+ + A^- I......0.095...0.....0 So (H^+) = (A^-) = 0.095*0.016 Substitute into Ka expression and solve for Ka.

Chemistry
............HClO ==> H^+ + ClO^- I..........0.015.....0......0 C...........-x.......x......x E.........0.015-x....x......x Ka = (H^+)(ClO^-)/(HClO) Plug in the E line into Ka expession, solve for x, then %ionization = [(x)/0.015]*100 = ?

Chemistry
Plug into the Henderson-Hasselbalch equation and solve for the ratio you want. Post your work if you get stuck.

Chemistry
Use the Henderson-Hasselbalch equation. pH = pKa + log[(base/(acid)] You know pH, you can calculate pKa (convert Kb to pKb then pKa + pKb = pKw = 14), you know (NH3), solve for (acid; i.e., NH4Cl). Then M NH4Cl = mols/L. You know M and L, solve for mols. Then mols = grams/...

Chemistry
Where is the H2O2 coming from? Do you have an equation?

Science
It would help if we knew the story behind the hot and cool liquids; ie. a little about what you did in this experiment (or a movie you saw or a virtual experiment)

Chemistry
2[MnO4]^- + 5[C2O4]^2-+ H^+ ==> 2Mn^2+ + 10-CO2 + etc. I balanced only the redox pat. Use PV = nRT and calculate n = number of mols. mols CO2 needed x (2 mol MnO4/10 mols CO2)= mols KMnO4 needed. Then M = mols/L. ou know M KMnO4 and mols KMnO4. Solve for L and convert to mL...

Science Chemistry
q1 - heat needed to go from 62 C to 100 C. q1 = mass H2O x specific heat H2O x (Tfinal-Tinitial). Tf is 100 and Ti is 62. q2 is heat needed to convert the sample of water at 100 to steam at 100. q2 = mass H2O x heat vaporization. So q1 + q2 = 4350 J I show q1 above and q2 ...

Chemistry
1. First, this has no answer since you don't know if the solute is ionic or not.Also, I don't know much about the morality of solution. I do know about molality. Assume it is non-ionic, then dT = Kb*m dT is 0.633, you know Kb, solve for m. 2. dT = Kb*m dT you know, Kb ...

Chemistry
I agree with your numbers. Yes, B is a small number but think about it. (a) you didn't have but a microgram initially which is small at the beginning. With a half life of 55 sec (approx 1 min) you have gone through about 60 half lives in 1 hour which leaves very little ...

Chemistry
k = 0.693/half life. Calculate k. Then, ln(No/N) = kt No = 1E-6 Solve for N. k from above. Plug in t in seconds if youu ue 55 sec to calculte half life. Convert to percent Post your work if you get stuck.

@ Vivian---CHEMISTRY
Don't piggy back your question on another question. Usually those get ignored. When you repost as a separate question, show the equation you want to use to go from chalcopyrite to Cu.

CHEMISTRY
Yes, that's ight. You know, of course, that the exponents 1 are not needed; however, there is nothing wrong with putting them there AND it serves to remind you each time to place an exponent. Many of my students through the years forgot the exponent. Good work!

CHEMISTRY
Write the expression for Ksp Subtitute the numbers and solve. Post your work if you gt stuck.

CHEMISTRY
Ksp = (Ag^+)^2(C2O4) but I don't understand why you aren't able to write that down with ease. If you will tell me what your problem with that is perhaps I can shed some light on how to do it.

CHEMISTRY

CHEMISTRY
I have been in this business a LONG time and I've never heard of silver nortonate. Tell me something abouat it. Nor do I know the identity of Ag2NtO4

science
The Ag^+ adds to the [CO3]^2- to form a ppt of Ag2CO3. What does this indicate? To me that the Ksp for Ag2CO3 is exceeded. By the way, noting the subject as chemistry will get an answer a little faster than denoting it as science. Science, of course, is correct; however, as a ...

chemistry
I assume you mean the equilibrium mols are as given and you want to know Kc. (IBr) = 0.2/1 L - 0.2M (Br2) = 0.1/1) = 0.1M (I2) = 0.1/1) = 0.1M Then Kc = (Br2)*(I2)/(IBr)^2 Substitute and solve for Kc.

Economics
I worked this problem for you about 4 or 5 hours ago. https://www.jiskha.com/display.cgi?id=1512514097

oops---AP Chemistry
LOL. HOURS ago.

AP Chemistry
I worked this problem for you about 4 or 5 yours ago. Here is a link. https://www.jiskha.com/display.cgi?id=1512514097

Chemistry
dHrxn = [BE reactants] = [BE products] Here is tutorial http://www.kentchemistry.com/links/Kinetics/BondEnergy.htm Post your work if you get stuck.

Basic Word and Excel
Just off hand, if you know how to(REALLY) use excel, you could programs it to do all of them.

chemistry
Balance the equation. Convert g butane to mols. Using the coefficients in the balanced equation, convert mols butane to mols CO2. Use PV = nRT substitute and solve for P of CO2

AP Chemistry
C4H10O + 6O2 ==> 4CO2 + 5H2O Burning 1 mol butanol uses 5 mols O2 (5*32 = 160 grams O2). How many grams O2 will be needed to release 26,400 kJ? That's 160 g O2 x (26,400 kJ/2,710 kJ) = ?

oops--algebra 1
Better review my subtraction rules.

algebra 1
a isn't right. y-6 = -12(x+4) y-6 = -12x - 48 y = -12x -48+6 y = -12x - 44

Chem
dHrxn = (n*BE reactants) - (n*BE products) BE = bond energy.

Chem
See other post above.

Chemistry As
I have no idea what the question is (I know it's molar mass but not the identity of h3x.nh20) nor do I understand the so-called answered that follow. Sorry.

chemistry
The shorter way to work this is harder to explain so let me show you the long way. First assume a value for T, use PV = nRT, and solve for P. P = ? V = 25.0L n = 2 mols (we'll call this n1) R -= 0.08206 T = 273. After you get P, use PV = nRT again. Use the same valus for R...

Chemistry
1 mol NO = 14 + 16 = 30 grams. 4 mol NO = 120 g 17.7 kJ are released for 120 g NO so how much will be released for 1 g? That's 17.7 kJ x (1/120) = ? kJ. Released kJ means an exothermic reaction and that makes the dH = a negative number.

Inorganic Chemistry
[PCl4]^+ is sp3 which is a tetragedral shape; however, note that the electrons fit exactly; i.e., P = 5 and 4*7 = 28 for Cl for total of 33 for PCl4 or 32 for [PCl4]^+. For PCl6, it is octahedral which is d2sp3; however, adding an electron to make it [PCl6]^- adds an extra ...

Chemistry
https://en.wikipedia.org/wiki/Saponification

Science
She traveled 300 meters; the displacement is zzero. The displacement is the difference between where she started and where she ended.

Chemistry
Right

Chemistry
To write the net ionic equation, first write the total (complete) ionic equation, remove ions that appear on both sides of the equation, the net ionic equation is what is left. Try that on this one. You should be left with H^+(aq) + OH^-(aq) ==> H2O(l) I included the phases...

Chemistry
[NH4]^+ +(aq) + OH?(aq) + H^+(aq)+ Cl^?(aq)==> [NH4]^+(aq) + Cl^-(aq) + H2O(l)

Chemistry
And what kind of help do you need?

science
It is a chemical reaction. More specifically it is a single replacement reaction.

Chemistry
What are my choices? You could mean oxidation/reduction or physical/chemical or in number of other choices. My guess is you want to know if it is a chemical or physical change. It is a chemical change because the peroxide is being decomposed into H2O and O2. The bubbles are O2...

Chemistry
No, but you never should need to ask this question because you can figure it out yourself. Note: There are two H atoms on the left from H2O2.There are two H atoms on the right from H2O. That's balanced for H atoms. On the left there are two O atoms from the H2O2. On the ...

Chemistry
This is not ideal but we do this. 2Al(s) + 3I2(s) ==> 2AlI3(s)

179,000 x 0.06 = ? commission earned. Written a a proportion I would write: (1/0.06) = (179,000/x)

curious
The webmaster is Leo and he runs this site. All of the tutors are volunteers and most are retired teachers. Some of us are long in the tooth.

chemistry

chemistry
This is another Clausius-Clapeyron problem You need to remember the definition of boiling point. At the normal boiling point, the vapor pressure equals atmospheric pressure; i.e., at 391 K the vapor pressure is 1 atm or 760 torr. Plug in the numbers and turn the crank.

Chemistry
I'm sorry but I don't understand the problem. It's the last line I don't get.

ChemistryDiethyl ether () was one of the first che
Use the Clasius Clapeyron equation.

Chemistry
You can do this two ways. 1. Determine the solubility of Ca(OH)2 from the Ksp and compare with 0.379 g. 2. Determine Qsp, using the 0.370 g, and compare with Ksp. If Qsp>or=Ksp, it is saturated. I'll show you how to do 1. mols Ca(OH)2 in 0.370 g = 0.370/molar mass Ca(OH...

ChEmIsTrY
The term alpha ray is a misnomer. In the past alha rays and alpha particles were used interchangeably. B is the correct answer to this queation. I think all of this got started because x-rays really are rays and x-rays are observed with alpha and beta "rays" and &...

@SimplengTao
To amplify that point, giving answers with no explanation doesn't tell the student HOW to do it on his/her own. The idea in being a student is to learn to think by/for yourself.

Chemistry
........PbI2 ==> Pb^2+ + 2I^- I......solid.....0........0 C......solid.....x........2x E......solid.....x........2x Ksp = (Pb^2+)(I^-)^2 Ksp = (x)(2x)^2 So the problem tells you the value of 2x. Substitute 2x and x into the Ksp expression and solve for Ksp.

Chemistry
mols H2O = grams/molar mass = 1800/18 = ? Then there are two atoms H for every mole of H2O; thereforeare, there are twice the number of H atoms as you have of H2O molecules.

oops typo--Chemistry
That's 6.02E23 of course. That last line is just gibberish. Ignore that.

Chemistry
A mole of ANYTHING = 6.02E23. be it atoms, molecules, stars, marshmallows. It's just another unit. For exasmple, a dozen is 12, a gross is 144 whatever, and a mole is 5.02E23 of anything. ,p;eci;es

College Chemistry

Chemistry
We can't draw diagrams on this forum. You have three isomers of C2H2Cl2. They are given below and you can (should) draw the structures from this. 1,1-dichloroethylene 1,2-dichloroethylene (the cis form) 1,2-dichloroethylene (the trans form) Draw all of th structures so you...

Chemistry
I don't know how much detail you want but here is a fairly good explanation of what goes on in the process. https://en.wikipedia.org/wiki/Blueprint

Chemistry
My calculator reads 91.66 which rounds to 91.7. If your prof is picky I would note that you are allowed only two significant figures in the answer (both 44 and 48 have two s.f.) so I would report 92%.

Chemistry
Theoretical yield is TY = 48 Actual yield is AY = 44 % yield = (AY/TY)*100 = ?

Chemistry
Frankly, I don't know how your prof uses those terms. In my book a trial titration is a good one but it's just one of several; i.e., one may do 3 trial titrations and use the average in calculations. A rough titration is one is which we aren't too careful and the ...

Chemistry
I have estimated all of these calculation so it will be necessary for you recalculate all of them. I assume you mean to calculate the molarity of the H3PO4 solution but that isn't clear in the problem. mols KOH initially = M x L = about 0.02 You diluted this to 250 mL and ...

CHEMISTRY
A is false. Adding a catalyst increases the rate of reaction but not the equilibrium. D is true. That's exactly what a catalyst does. What is your take ton the others.

chemistry
See the response by Bob Pursley above.

chemistry
You solved for M in pi = MRT and you want to find molar mass. M = mols/L. You know M from the above, you know L (0.6), solve for mols like this. mols = M x 0.6 = ?. Knowing mols, use mols = grams/molar mass, then molar mass = grams/mols.

chemistry
pi = MRT pi = 808 torr. Convert to atm. M = ? R = 0.08206 T = 21 C. Convert to kelvin. Solve for molarity = M Then M = mols/L with L = 0.6 Find mols. Finally, mol = grams/molar mass. You know mols and grams, solve for molar mass. Post your work if you get stuck.

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