Friday
April 18, 2014

Posts by DrBob222


Total # Posts: 41,788

chemistry
Oxidation is the loss of electrons. Reduction is the gain of electrons. Zn is +2 on the left and +2 on the right. H is +1 on the left and +1 on the right. O is -2 on the left and -2 on the right. Cl is -1 on the left and -1 on the right. Anything change? nope. So nothing is ox...

chem Help
Substitute the equilibrium concentrations into the Kc expression and solve for Kc. Use this below. ...........N2 + O2 ==> 2NO I.......0.200..0.200....0.800 C.........+x...+x.......-2x E.....0.200+x..0.200+x...0.800-2x Substitute the E line into Kc expression along with the ...

Chem
mols Mn(OH)2 = grams/molar mass = approx 3E-6 but this is an estimate. You should recalculate this and all that follows. Then M = mols/L = about 3E-6/0.1L = about 3E-5. ...........Mn(OH)2 ==> Mn^2 + 2OH^- I..........solid........0.......0 C..........solid........x.......2x ...

Chemistry !
See your other post.

Chem Please Help
.........A <==> 2B I......2.30M.....0 C........-x......2x E......2.30-x....2x Kc = 5.04E-6 = (B)^2/A Substitute the E line into Kc expression I have above and solve for x. Then 2x = (B)

Chem 2 help
0.800 mol/2.00L = 0.400M ........2SO3 <==> 2SO2 + O2 I.....0.400M........0.....0 C.......-2x........2x.....x E.....0400-2x......2x.....x x = O2 = 0.140mol/2.00L = 0.07M Then 2x = 0.140M = (SO2) and 0.400-0.140 = 0.26M = (SO3) Substitute these into the Kc expression and s...

Chemistry - Solubility
I must confess I don't understand this at all.

chemistry
I guess A is one atom, B is another atom, what's n. Perhaps the number of B atoms? Or is that supposed to stand for the number of unpaired electrons?

chemistry
what's abn mean?

chemistry
qwater = mass H2O x specific heat H2O x (Tfinal-Tinitial) Note: Tfinal-Tinitial = delta T = 10.20 C.

Chemistry
I can't type this in the format you want because the site won't handle it. So n1 will be a and n2 will be b. 1/wavelength = R(1/a^2 - 1/b^2) n1 = a = 1. 1^2 = 1 n2 = b = 3. b^2 = 9 1/wavelength = R(1/1 - 1/9). R = 1.0973E7 wavelength will be in meters. Then E = hc/wave...

Chemistry
2NaN3 ==> 2Na + 3N2 mols N2 gas = grams/molar mass = x mols N2 Using the coefficients in the balanced equation, convert mols N2 to mols NaN3. That's x mols N2*(2 mols NaN3/3 mols N2) = x mols N2*(2/3) = ? mols NaN3. Then ? mols NaN3 x molar mass NaN3 = grams NaN3.

Chemistry
Same process + a little more from the NaN3 problem above. Find mols aspirin produced by 100 g salicylic acid, convert to grams aspirin, and that is the theoretical yield. Then % yield = (actual yield/theoretical yield)*100 = ?

chemistry
Let CH3COOH = HAc .......HAc + NaOH = NaAc + H2O At the equivalence point you have NaAc, sodium acetate. The acetate ion (C2H3O2^- or Ac^-) is hydrolyzed as follows and I assume that is solid NaOH placed in the acetic acid, there is no volume change, and (Ac^-) = 1M: ............

Chemistry
Absolutely false. It will increase the solubility BECAUSE of the formation of the complex Ag(NH3)2Cl AgCl + 2NH3 ==> Ag(NH3)Cl

Chemistry 2
I might add that the excess heat (but light also may be involved) is absorbed by the surroundings in exothermic reactions. Next, you need to talk about endothermic reactions and how the heat needed to make the reaction go is supplied by the surroundings.

Chemistry 2
This is a long discussion question. How would you like us to help you with this assignment?

chemistry
So I do all the typing and thinking while you compare. That takes up my time so I can't answer other questions. It's better for you to do all the typing and thinking and let me compare. Much more efficient process.

chemistry
Another discussion question.I shall be happy to critique your work.

Chemistry
mols = grams/molecular weight

chem 2
We need the phases. Is that H2S(g) ==> H2(g) + S(g) or S(s) I assume H2S(g) ==> H2(g) + S(g) I........0.111.......0.......0 C.........-x.........x.......x E.......0.111-x.....x........x Kp = 0.791 = p(H2)*p(S)/p(H2S) Solve for x = p(H2) = p(S) p(H2S) = 0.111-x Then Ptota...

Chem 2
You can check these things by substituting your value of x into the Kc expression and see if you come out with 1.8. I did this with 0.0921 and it doesn't pan out. When I solve the quadratic I obtained 0.09 for x and that checks out.

Chem 2
I can't check this without knowing Kc. If your value of x is correct that is the value of PCl3 and Cl2 because you probably did it this way. ........PCl5 ==> PCl3 + Cl2 I.......0.0945.....0.....0 C.........-x.......x......x E.......0.0945-x...x......x You can see x = (P...

Chem
40.0 mL x 0.14 M HBrO = 5.60 millimols 5.0 mL x 0.56 M NaOH = 2.8 mmols. .........HBrO + NaOH ==> NaBrO + H2O I........5.60 add.............2.80.............. C.......-2.80..-2.80.....+2.80 E........2.80....0........2.80 Use the Henderson-Hasselbalch equation with the E lin...

chemistry
(NO) = 2.8E-2/1.4L = about 0.02M (Cl2) = 1.4E-3/1.4L = about 0.001M (NOCl) = 5.9/1.4L = about 4.21 Qc = (NOCl)^2/(NO)^2*(Cl2) Qc = (4.21)^2/(0.02)^2*(0.001) = approx 5E7 but you should confirm that. Compare that with Kc =1E7 Qc > Kc; therefore, numerator is too large and/or...

chemistry
(HBr) = 3.20mols/21.3L = about 0.150 but that's an estimate. It's just like it sounds. I = initial; C = change; E = equilibrium. I assume you made a typo and meant Br2. ..........H2 + Br2 ==> 2HBr I.........0.....0......0.150 C.........x.....x.......-x E.........x.....

chemistry
Just like the HBr problem.

chemistry
Li2O + HOH ==> 2LiOH mols H2O = 85,000/18 = estimated 4722 Now convert mols H2O to mols Li2O using the coefficients in the balanced equation. That's estimated 4722 x (1 mol Li2O/1 mol H2O) = about 4722 mols Li2O. Now convert that to g Li2O. g = mols x molar mass. Go bac...

chemistry
Ptotal = pH2O + pgas 745 mm = pH2O(look up vapor pressure H2O @ 26 C) + pgas. Solve for pgas which is the pressure of the DRY gas. Then PV = nRT. You know P (use pressure of dry gas), n, R, and T; solve for V in liters.

Chemistry
1/wavelength = R*(1/4 - 1/x^2) Convert wavelength to meters. You know R, the 1/4 is 1/2^2. X will be the higher orbit.

chemistry
Hg22+ ==> 2Hg2+ + 2e Hg22+ + 2e ==> 2Hg

Chemistry
Use the Henderson-Hasselbalch equation and the total buffer (both equations) and solve simultaneously. 7.45 = 7.21 + log (base/acid) I get base/acid = estimated 1.8 but you need to do it more accurately. And base + acid = 1M Solve simultaneously. I obtained approximately 0.36M...

chemistry
You can google "table ionization potentials".

chemistry
I would look at the ionization potential for each of the elements. The largest ionization potential is the one with the greatest attraction.

Chemistry
Watch the units. dGo part in kJ and +RTlnK part in J

Chemistry
delta G rxn = dGo + RTlnQ where Q = (ADP)(HPO4^2-)/(ATP)

Chemistry
dG = -RTlnK. Solve for K. Then .......A + B ==> C I..0.30.0.0.40...0 C....-x....-x....x E..0.30-x..0.40-x..x Substitute the E line into Keq expression and solve for x, then evaluate concn A and B. Don't forget to use dG in J/mol and not kJ/mol

Chemisty
Will you check that dS = -287.5? I may have it mixed up with another problem but I seem to remember that as being delta G or something like that but not dS. Thanks.

Chemisty
Didn't I do this for you last week? As I remember you didn't understand my explanation. Or am I wrong?

chemistry
N2 + 3H2 ==> 2NH3 delta E = q + w I would look up delta Hof. Then dHrxn = (n*dHoproducts) - (n*dHoreactants) and that will give you q. W is -p*delta V. Use PV = nRT. You know n, R, P, and T; solve for V at the end. Knowing mols formed you can calculate mols N2 and H2 initia...

chemistry
A complete combustion occurs when there is sufficient oxygen to react completely with the other material; i.e.., when the material being oxidized is the limiting reagent. An incomplete combustion occurs when there is insufficient oxygen to burn the other material completely; i...

Chemistry
Is this part of a problem and there is more to post? It appears to me you are have delta S vap and that x 7.40 will do it. But I may be confusing it with something else. If you have more to the problem please post it.

Chemistry
I tried to find the response I made to your earlier question but I can't find it. At any rate, it doesn't matter what is used to standardize the NaOH. What is important is how many of the H atoms of the H2CO3 formed you titrate. That depends upon what kind of indicator...

Chemistry
This is a heat problem, not a chemical problem so it really makes no difference at all about the identity of the acid or base. q = mass fluid x specific heat fluid x (Tfinjal-Tinitial) q is what you solve for. mass = 195 mL = 195 g with since density is 1.00 g/mL. specific hea...

Chemistry - Solubility
Mg(OH)2 ==> Mg^2+ + 2OH^- Ksp = (Mg^2+)(OH^-)^2 When NH3 is added to the solution of MgCl2 (which is quite soluble) the NH3 reacts with the H2O to form NH4^+ + OH^-. That increases the OH^- enough to form a Mg(OH)2 ppt because Ksp for Mg(OH)2 is exceeded. (SO YOU SHOULD HAV...

Chemistry - Solubility Product
See your other post.

Chemistry
You had a saturated solution of PbCl2 which means that (Pb^+)(Cl^-)^2 was just equal to Ksp. When you added dilute HCl, you increased the (Cl^-) [the common ion effect] and this DECREASED the solubility of PbCl2; therefore, some of the PbCl2 pptd and that's what you saw. P...

chemistry
HCN. H to C is sp C-N is sp. Then twp p-p bonds form the other two to make C-triple bond-N

chemistry
I'm sorry. That's a bad habit of mine; i.e., making a comment but not including the url.Here is is. http://en.wikipedia.org/wiki/N-Bromosuccinimide

chemistry
We can't draw structure on this forum but here is a site that give the structural formula. You can add the dots and needed.

chemistry
I expect it's dipole-dipole.

Chemistry
You can find other answers to the CO2 question and some analytical chemists don't agree with this but I think it may or may not make a difference. When CO2 reacts with NaOH it forms Na2CO3. CO2 + 2NaOH ==> Na2CO3 + H2O. For every mole CO2 added we form 1 mol Na2CO3 and ...

chemistry
3Ba^2+ + 2PO4^3- ==> Ba3(PO4)2(s) Convert mols each to mols product. 0.5 mol BaCl2 x (1 mol product/3 Ba^2+) = approx0.167 mols Ba3(PO4)2 produced. 0.2 mol Na3PO4 x (1 mol product/2 mol PO4^3-) = 0.1 mol Ba3(PO3)2 produced. In limiting reagent problems the smaller number AL...

Chemistry
KE = (1/2)*m*v^2 KE in joules = (1/2)*1533 kg x v^2 Convert 90.6 km/hr into m/s and substitute into the above formula, Solve for KE. I get 25.17 m/s for the conversion but you should confirm that. .

Chemistry Help Please!!!
1) KaKb = Kw = 1E-14 2) I have no idea what NaC2 is.I suspect you were trying to write NaC2H3O2. I would expect the pH of a 0.1M solution of NaC2H3O2 to be the same as a 0.1M solution of KC2H3O2. The pH is determined by the hydrolysis of the C2H3O2^- ion and that would be the ...

chemistry
There is a simple dilution formula you can use for all of these. c1v1 = c2v2 c = concentration v = volume 1M x ?mL = 0.1M x 100 mL ?mL = (0.1M x 100 mL)/1M = 10 mL

Chemistry
I think the % acetic acid will be too high. Standardization step: mols KHP = grams KHP/molar mass KHP mols NaOH = mols KHP M NaOH = mols NaOH/L NaOH Titration vinegar step: mols NaOH titrant = M x L mols acetic acid = mols NaOH g acetic acid = mols acetic acid x molar mass % a...

chemistry
This is a little confusing to me; i.e., #1 will make a buffer but not a very good one. #4 will have a pH = 7.0 but not good buffering characteristics. I need to know what you don't understand and what have you answered (and why?)

chemistry
I don't think so but you may find something here. https://cs.uwaterloo.ca/journals/JIS/cayley.html

Chemistry
I don't know exactly how the experiment was conducted but I think 1 is right. For 2, however, I think the results must be either too high or too low (but see the note below). If too little liquid is placed in the flask that means that vapor cannot fill the flask so your se...

chemistry
mols = grams/molar mass

Chemistry
Mg + H2SO4 ==> MgSO4 + H2 mols H2 = 9.5L/22.4L = 0.5 ESTIMATED so you should redo the calculation as well as all that follow for they are estimates also. 0.5 mol H2 means you started with 0.5 mol H2SO4 g H2SO4 = mols H2SO4 x molar mass H2SO4 = estimated 42 grams The solutio...

chemistry
First determine the concn of HNO3 in the 19.0% stuff. 1.11 g/cc x 1000 cc x 0.19 x (1 mol/98 g) = estimated 2 mol/dm^3 Then use the dilution formula of c1v1 = c2v2 2*v = 2*3 Solve for v = approx 3 dm^3 Remember to recalculate all of the above.

Chemistry
Did you read my response to your earlier post with this same question? If not you should go back to read it. If so, then please go through and explain, in detail, exactly what you don't understand about my answers. If I answer this post I'll just rewrite what I've ...

CHEMISTRY
First part. You have subtracted correctly and MASS of the water in the flask is 248.4 grams. Then since mass = volume x density you can rearrange that to volume = mass/density mass = 248.4g and density of the H2O is 1 g/mL (from the problem), then 248.4g/1 g/mL so volume is 24...

Chemistry
I work these LR problems the long way. CuCl + H2S --> Cu2S + 2HCl mols CuCl = grams/molar mass mols H2S = grams/molar mass Using the coefficients in the balanced equation, convert mols CuCl to mols Cu2S. Do the same for mols H2S to mols Cu2S. It is likely that the values wi...

chemistry
MgF2 ==> Mg + F2 ......1.65kg..2.58 kg So you must have started with 1.65 + 2.58 = ? kg MgF2. MgF2 ==> Mg + F2 .......1.50kg..? I would use ratio/proportion on this. (1.65/1.50) = (2.58/x) Solve for x.

Chemistry URGENT
Linda, I did these for you earlier. You've just copied my work Is it that you want a second opinion?

Chemistry URGENT
Linda, I did this for you earlier, also. The only problem I see is that you made a typo in transcribing my answer. You wrote CO instead of CO2 and that's why it wouldn't balance for you.

Chemistry
I'm confused. You have an unknown base, you're titrating with HCl, and you're adding NaOH? Something strange in Denmark.

Chemistry
After mixing but before reacting the concns are (Ag^+) = 0.0023/2 = 0.00115M (CN^-) = 0.21/2 = 0.105M I've divided by 2 since equal volumes of each have been added which means both dilute each other by a factor of 2. Then we do an ICE chart. ..........Ag^+ + 2CN^- --> A...

Chemistry Help Please!!!
Cu^2+ + 4NH3 ==> Cu(NH3)4^2+ blue. May be pale blue in very dilute solutions but more often is a deep blue color. Ni^2+ behaves similarly but not the same color.

CHEMISTRY
H2S ==> SO2 mols H2S = 20.0g/molar mass = approx 0.6 but you need to do it more accurately. There is 1 mol S in H2S and 1 mol S in SO2; therefore, you should be able to produce 0.6 mols SO2. Then g = mols x molar mass. Remember to do the math yourself because 0.6 is an esti...

Chemistry
Ecell = Eocell + (0.0592/#e)log(Pb^2+)/(Pb^2+) Ecell = 0.1776 Eocell= I don't have my text handy but I think this is -0.126. You should verify that. #e = 2 For the log term, the top number there is 1M and the lower number is x. You solve for x

chemistry
C6H10O5 + O2 ==> CO2 + H2O Here is what I do. Balance C since you know you must have 6C on the right. C6H10O5 + O2 ==> 6CO2 + H2O Next look at H. There are 10 on the left so we need 10 on the right. C6H10O5 + O2 ==> 6CO2 + 5H2O Now we know for sure, since the 6 and 5 ...

Chemistry
Look at your cellulose balance above and see how I did that step by step. 2Fe + O2 ==> 2FeO I don't understand why you have trouble with that. 4Fe + 3O2 ==> 2Fe2O3 This one can be a little trickier but here is how I do it. Fe + O2 ==> Fe2O3 I start a little backwa...

chemistry
Cu(NO3)2(s) + H2O ==> Cu^2+(aq) + NO3^-(aq)

analytical chemistry
Use the Henderson-Hasselbalch equation.

chemistry
[(g solute)/(g solution)]*100 = % g solute = x g solution = 24 % = 13.5 Substitute and solve for x

Chemistry
You're right for #3. dG = 0 at equilibrium.

Chemistry
2. Consider the following reaction: C3H8(g) + 5O2(g) ---> 3CO2(g) + 4H2O(g) One would predict that A) ΔH is positive and ΔS is positive for the reaction. B) ΔH is negative and ΔS is negative for the reaction. C) ΔH is negative and ΔS is positiv...

Chemistry
1. The following reaction is spontaneous at all temperatures: CaC2(s) + 2H2O(l) ---> Ca(OH)2(s) + C2H2(g) Which of the following statements is true? A) ΔG is positive at all temperatures. B) ΔG is positive and ΔS is positive. C) ΔH is negative and Δ...

oops---Chemistry
What I stated as answer for #2 actually is B of #1.

Chemistry
I think for #2 you are to use Keq expression with dG which is dG = -RTlnK. and go from there. So you know R, and T, K = p(H2)/p(H2O) substitute and solve for dG.

Chemistry
Yes, for #1 use dGo = dHo - TdSo. That will give you dGo. Then if you assume dH = dHo and dS = dSo and use T = 500K.

Chemistry
IT doesn't tell me anything. WHAT is incorrect? What number did you get? If you used my numbers I'm not surprised it (the answer you obtained) is incorrect. Did you read where I said it was approximate? Did you work it out from the beginning. Probably not.

Chemistry
2.30 g/L = 2.30/333 mols/L = approx 0.007 M but this is an estimate. ..........AB3 ==> A^3+ + 3B^- I........solid.......0......0 C........solid...0.007...3*0.007 E........solid...0.007....0.021 Ksp = (A^3+)(B^-)^3 Ksp = (0.007)(0.021)^3 = ? Check my work.

Chemistry
See your post on AB3

Chemistry
I worked this for you about 4-5 hours ago.

chemistry
Do you have a question?

Chemistry
I don't think so. Post your work and I'll find the error. And you need to define x.

Chemistry
Why not post one of them and let us find the error. This way we're running in circles.

Chemistry
The factor to which you refer is i, the van't Hoff factor. It is 4 for AlCl3.

Chemistry
Au, Pt, Sn, Ag in that order. q = mass x specific heat x delta T Solve for specific heat or sp.h. sp. h. = q/m*delta T So for the same m and delta T, small sp.h. requires small q; large sp.h. require large q. But you could think of an example and get the same result. If I heat...

Chemistry
The problem with 4 is not the +/- 1/2, you can't have ml of one with ell = 0 m ell values are + ell to -ell. If ell = 0, you may have m ell of zero only. Can't be + one.

Chemistry
My original answer didn't post. I said that you don't say but obviously the Cu (metal???) must be laced in solution and it PROBABLY formed Cu^2+ in which case the ppt will be CuCr2O7. Try that.

Chemistry
See your other post.

Chemistry
We have a problem here. You have Fe^2+ on the left and Fe^3+ on the right which means Fe has been oxidized. But there is no reduction. You can't have oxidation without reduction. I expect you meant Fe(NO3)3 on the left

Chemistry
I'm guessing but you need to decipher your post. Does CIE and NIE stand for complete and net ionic equation?

chemistry
Fe + 2HCl ==> FeCl2 + H2 1 mol Fe = 1 mol FeCl2; therefore, 10 mol Fe = 10 mols FeCl2.

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