Wednesday
July 30, 2014

Posts by DrBob222


Total # Posts: 43,225

Chemistry
It IS an exothermic reaction but I don't know that the release of CO2 is the reason. The entropy is +.

chemistry
Of course. van't Hoff factors are at best just good guesses; you might be closer to reality by picking something with i = 1; i.e., a complete non-electrolyte like ethyl alcohol or something like that.

chemistry
I think you must assume some things. 1. Since you know the solvent is water you can look up the Kf value of 1.86/mol. 2. You have your choice of solute so you can pick one that has an i = 1 or an i of some other value. 3. So 3.7 = iKm if you chose i = 2 you could pick a solute...

Chemistry
And in the "older" olden days it was amyl-propyl-ether

Chemistry
1) pH + pOH = pKw = 14. You know pH and pKw, solve for pOH. Not that hard if you can subtract. 2) I don't know where you're headed but M = mols/L or M strong acid is M of H^+ or pH = -log M.

oops --Damon--Science
I think Damon made a typo. That is kJ and not J.

chemistry
P4 ==> H3PO4 HNO3 ==> NO2

chemistry
Depends upon how much nano3 you want to make. That's the same kind of question as how many apples and how much flour are need to make an apple pie? How much ice cream is need to make a milk shake?

Chemistry HELP
AgNO3 + Cl^ --> AgCl ppts all of the Cl from NaCl and Cl from BaCl2. Na2SO4 + Ba^2+ ppts BaSO4 but leaves the NaCl intact with no reaction.

Chemistry HELP
I can get you started but you will need to fill in between the steps. Add AgNO3 to ppt all of the chloride (total chloride). Add Na2SO4 to determine barium.

Chemistry
sp1 is sigma bond single bond. sp2 is double bond; one sigma and one pi. sp3 is triple bond; one sigma and two pi.

Chemistry
Electrons in a higher energy level fall to a lower energy level; the difference in energy levels produces wavelengths of the electromagnetic spectrum. Some of that falls in the realm of visible light.

chem 11
mols NaOH = grams/molar mass = ? M = mols/L solution = ?mols/0.300 = ?

Chemistry
Ksp = (Mn^2+)(OH^-)^2 2.1E-13 = (x)(2x + 0.07)^2 To avoid a quadratic assume 2x + 0.07 = 0.07 2.1E-13 = (x)(0.0708)^2 x = (2.1E-13/(0.0708)^2 etc.

Chemistry
Use PV = nRT to caluclate mols ClF from the 343 mL value. I obtained 0.03. Use mols = grams/molar mass to determine mols UF6. I obtained 0.01. Then U + ClFn ==> UF6 + xClF .........0.03...0.01...0.03 You have 0.06 mols F in 0.01 mols UF6 (6 mols F/mol UF6) x (0.03/0.06) = 3...

Chemistry
12.0g MnI2/0.75 = ? g MnI2 to start accounting for the 75% yield = approx 16 mols MnI2 = grams/molar mass = 16/about 300 = ? Convert to mols F2. That's ? mols MnI2 x (13mols F2/2 mols MnI2) = ? x 13/2 = x mols MnI2. Convert to grams. g = mols x molar mass

Chemistry
I would convert pH to pOH first, then convert that to OH^- pH + pOH = pKw = 14 You know pH and pKw, solve for pOH, then pOH = -log(OH^-) Solve for OH^- and substitute in equations below. I obtained about 0.07M ...........Mn(OH)2 ==> Mn^2+ + 2OH^- I..........solid........0.....

Chemistry
http://chemwiki.ucdavis.edu/Physical_Chemistry/Quantum_Mechanics/Atomic_Theory/Intermolecular_Forces/Polarizability

chemistry
2HCl + X2CO3 ==> H2O + CO2 + 2XCl mols HCl = g/molar mass = 7.3/36.5 = ? M HCl = mols/dm3 = about 0.2 In the titration, mols HCl = 0.00281 x 0.2 = ? mols X2CO3 = 1/2 that from the coefficients M X2CO3 = mols X2CO3/25 = ?

chemistry
It's an endothermic reaction. It's a redox reaction. It's a decomposition type reaction but I would think thermal dissociation would fit also.

chemistry
You made a typo. O is 16 not 6. i) concn G is 0.1 mol/dm3. Calculated as follows: mols NaOH = g/molar mass = 0.1/40 = 0.025 M NaOH = 0.025/0.25 = 0.1 mol/dm3 ii)Note: 1 L = 1 dm3 and M = mols/dm3 2NaOH + H2X ==> Na2X + 2H2O mols NaOH used = M x L = 0.1M x 0.025 = 0.0025 mol...

Organic Chemistry
See 3-methyl butan-1-al See 3,3-dimethyl butan-2-one

Organic Chemistry
See benzaldye + H2 ==> http://en.wikipedia.org/wiki/Benzyl_alcohol

chemistry
Aspirin used for aches and pains and for headache. Na2CO3 used for acid stomach. Salicylic acid used for athlete's foot.

chemistry
Depends upon how much Al2O3 and/or H2 you started with.

CHEMISTRY
mols o2 gas = grams/molar mass Using the coefficients in the balanced equation, convert mols O2 gas to mols CO2 Now convert mols CO2 to grams. grams = mols CO2 x molar mass CO2 All caps makes your post difficult to read.

Calculation in chemistry
This is done the same way as the last problem with Cu and Ag. step 1. Write and balance the equation. step 2. convert grams to mols. step 3. convert mols of what you have to mols of what you want. step 4. Not asked for in this problem but if needed, then grams = mols x molar m...

Chemistry
Cu + 2AgNO3 ==> 2Ag + Cu(NO3)2 mols Cu = grams Cu/atomic mass Cu Using the coefficients in the balanced equation, convert mols Cu to mols Ag. Now convert mols Ag to grams. g = mols Ag x atomic mass Ag.

science
What's the time?

Chemistry
(P1/T1) = (P2/T2) T must be in kelvin.

Science--Myanswer Plz, plz
1, 3, 6 wrong. 7 is A.

chemistry
https://www.google.com/search?q=monomer+structure+DNA&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&channel=sb

chemistry
https://www.google.com/search?q=polymer+structure+DNA&client=firefox-a&hs=f9G&rls=org.mozilla:en-US:official&channel=sb&tbm=isch&tbo=u&source=univ&sa=X&ei=nJt_U7GKAeiqsQTh84HoCg&ved=0CDkQsAQ&biw=1143&bih=688&dpr=0.9https://www.google.com/search?q=monomer+structure+DNA&client=f...

Chemistry
IO3^- ==> I2 First balance the I so we are working with apples and apples and not apples and oranges. I on left is +10; on right is 0 add 10 e to left side 2IO3^- + 10e ==> I2 charge on left is -12; right is zero. Add H^+ to left and H2O to the right. 2IO3^- + 10e + 12H^...

chemistry
right about what? What is unsaturated?

chemistry
I don't know. Few people have the tables/graphs of solubility vs temperature memorized. If you will post the solubility from you graphs/tables I can agree or disagree with you.

Chemistry
plasma etching, wet etching, oxidation, vapor deposition, alloys, should get you started.

SCIENCE HELP !!
1. Fe can lose either two or three electrons to form iron(II) or iron(III). 2. One element loses electrons to form + ions; one element gains those electrons to form - ions.

Chemistry
nope. A is true. B. The bp is higher. C. The fp is lower D. Since B and C are not true D can't be right. "When a non-volatile solute is dissolved in a volatile solvent, three things happen. A. The vapor pressure is lowered. B. The freezing point is lowered. C. The boi...

Chemistry
What is your hang up on this question?

Chemistry
I worked this problem earlier; if you can't find it I will give you a link.

Science(chemistry) please help me fast
You should expand on this but basically the heat from the room gives energy to the molecules, they move faster and faster with increasing heat and at some point in time the molecules begin to slip and slide over and around each other and it becomes soft enough to spread.

Science(chemistry)
See your other post.

analytical chemistry
First use the Henderson-Hasselbalch equation and solve for pKa. pH = pKa + log (base)/(acid) 10.30 = pKa + log [0.4/0.2] pKa = ? mmols B initially = 0.4 x 250 = 100 mmols BH^+ initially = 0.2 x 250 = 50 ..........B + H^+ ==> BH^+ I........100...0......50 add............25.....

chemistry
Yes you would; however, you have expanded the (0.1-x)(0.1-x) unnecessarily. I would have done it this way. It's less work. Keq = (x)(x)/(0.1-x)(0.1-x) Keq = x^2/(0.1-x)^2 sqrt (Keq) = x/0.1-x and go from there.

chemistry
You need to locate the caps key on yur keyboard and use it. The concn is 1mol/10 L = 0.1M ........CO2 + H2 --> CO + H2O I.......0.1...0.1....0.....0 C.......-x....-x.....x.....x E......0.1-x..0.1-x..x.....x Substitute the E line into the K expression and solve for x, then e...

chemistry
15g of what in 2 hrs?

Chemistry
The specific heat of H2O should be listed in your text but I think it is 4.184 J/g*c. Tfinal is listed in the problem as 100 C. Tinitial is listed in the problem as 25 C. Note that if you use specific heat in J/g*c you must change q from the first part of the problem from kJ t...

Chemistry
volume coal = 7.5*7*6.5 = aprox 340 cc mass = volume x density = approx 500g but you should recalculate this number and all of the others that follow because I've estimated all of them. ?kJ = apprx 394 kJ x (500/12) = ? and it is exothermic so it has a - sign. Then +q = [m...

Chemistry
You were able to get "how far"? I don't see anything but the question and the numbers. I can work the problem for you which won't help you. If you've watched Kahn academy, what do you not understand now. Let's take it from there. How far can you get o...

Chemistry
mols N2 = 145.8g/molar mass N2 = ? Convert mols N2 to mols NH3 using the coefficients in the balanced equation. Now convert mols NH3 to g. g = mols x molar mass. This is the theoretical yield. If the actual yield is only 90%, then g NH3 x 0.90 = ?

Chemistry
See your other post.

Science 1 question
Just to add my two cents' worth, I think the question is not clearly stated. I think it makes a difference WHEN. If this is at the START of the inhalation phase you have one answer or if it is at the END of the inhalation phase you have another answer.

Science(chemistry)
physical change

Science (A&P)
https://www.google.com/search?q=food+from+mouth+to+large+intestine&client=firefox-a&hs=M6C&rls=org.mozilla:en-US:official&channel=sb&tbm=isch&tbo=u&source=univ&sa=X&ei=H_J8U_2JFPKwsATMw4CIDA&ved=0CEwQsAQ&biw=1143&bih=688&dpr=0.9

chemistry
mols HCl = M x L = ? Using the coefficients in the balanced equation, convert mols HCl to mols Mg. Now convert mols Mg to g. g = mols x atomic mass.

Chemistry
See your problem above with Mg and HCl. This is the same type of problem. The 80.5% is handled this way. 285g impure iron(II) nitrate x 0.805 = ? g pure iron(II) nitrate

Science -Check Answers-
Both are wrong.

chemistry
P1V1 = P2V2

Science(chemistry)
law of constant proportions.

Chemistry
The limiting reagent problems are really just two ordinary stoichiometry problems solved more or less together. Here is how it is done. The first step is to write and balance the equation which you have supplied. CaCl2 + Na2CO3 ==> CaCO3 + 2NaCl Step2a. Convert g CaCl2 to m...

Science
http://en.wikipedia.org/wiki/Prepuce http://books.google.com/books?id=5XogAQAAMAAJ&pg=PA19&lpg=PA19&dq=define:preouce&source=bl&ots=CI40WcXkl_&sig=5WQoN85Ehia0eynrI-LJfSKFvpQ&hl=en&sa=X&ei=uRN8U-eKKtHNsQSyqYDAAQ&ved=0CDwQ6AEwBA#v=onepage&q=define%3Apreouce&f=false

Science
http://en.wikipedia.org/wiki/Prepuce

Chemistry
This isn't so much a normality problem as it is a dilution (concentration) problem. If you take 4 ml and dilute to 20 you have diluted it 5 times, right? Then another 50 times in the 1:50. So the total dilution is 5*50 = 250 times. So if you have 1N solution and it's d...

Chemistry
Solubility is 1g aspirin in 300 mL. So how much aspirin is lost with a 10 mL rinse and I use the term rinse lightly which I will comment on later. 1000 mg aspirin x 10mL/300 mL = 33.33 for the first rinse. 33.33 for the second rinse. 33.33 for the third rinse. Total is 100 mg ...

chemistry
I would name that 3,4-dimethyl-2-pentene.

AP chemistry
I don't like to do it this way because students ALWAYS get confusted so I'll put it together for you. heat lost by Al is mass Al x specific heat Al x (Tfinal-Tintial) heat gained by H2O is mass H2O x specific heat H2O x (Tfinal-Tinitial) So set heat lost + heat gained ...

AP chemistry
heat lost by aluminum + heat gained by water = 0 heat lost by Al = mass Al x specific heat Al x (Tfinal-Tinitial) heat gained by water = mass H2O x specific heat H2O x (Tfinal-Tinitial) Substitute into the heat lost + heat gained = 0 and solve for Ti.

Chemistry
I don't know where you obtained the 85 C? m = 312, right c = unknown, right The problem tells you delta T is 15, where did the 85 come from?

Chemistry
I hesitate to answer all of these for you for that way you aren't learning how to do them yourself. I will get you started. For the others show what work you've done, how you think the problem should be solved. and/or exactly what you don't understand about the pr...

Chemistry
Do you have suggestions for these?

Chemistry
.........Ag + ....xN2 --> AgxNy I......344.588.....0........0 add.............15.906......... C.....-344.588.....-x......359.503 So you end up with 359.503 You started with...344.588 How much N2 was added? Then N2 remaining = start-end = ?

Chemistry
If we look at this the reverse direction. H2(g) + 1/2O2(g) --> H2O(l) that's the heat formation liquid H2O in kJ/mol and my text shows that as -285.8 kJ/mol Then H2O(l) ==> H2O(s) is another 6.0 kJ/mol to form ice and freezing water to ice is exothermic so that shoul...

chemistry
PV = nRT

Chemistry
That's the best choice.

Chemistry
delta T = i*Kf*m So you want the highest delta T. i is the van't hoff factor, Kf is constant, molality is constant in this case so it appears to depend upon i. i = 1 for A i = 1 for B i = 2 for C i = 2 for what you have but I suspect you made a typo and that should be MgCl...

Chemistry
I don't know. I looked up the numbers in my text. Although they are slightly different I obtained essentially the same values you did; i.e., 128.2, 6.05, and -58.2 all in kJ/mol. I also looked up dGo in the same text and it was 130.4 at T = 298 and using dG = dH - TdS I ob...

Chemistry
heat gained by cold water + heat lost by warm water = 0 [mass cold H2O x specific heat H2O x (Tfinal-Tinitial)] + [mass warm H2O x specific heat H2O x (Tfinal-Tinitial)] \ 0 Substitute and solve for the only unknown, which is Tf.

chemistry
Look up the reduction potentials and add the oxidation half cell to the reductin half cell to obtain the Eocell. If it is + the rxn is spontaneous; if Eocell is - it is not spontaneous.

chemistry
What are you starting with?

Chem
mols Pb(NO3)2 = M x L = approx 0.28 mols PbCl2 formed = mols Pb(NO3)2 (see the 1:1 ratio for Pb(NO3)2/PbCl2 Then g PbCl2 = mols PbCl2 x molar mass PbCl2.

Chemistry
http://www.jiskha.com/display.cgi?id=1400465598

Chemistry
If you post your work so we know what you did perhaps we can find the error. Especially important is what are you using for Eo values.

chemistry
You should make a habit of looking to see if an earlier post has been answered. I answered this about 5-6 hours ago.

science help
For 1 read about tectonic plates. For 2 you didn't list them.

Chemistry
Mg^2+ + 2e --> Mg 2Cl^- ==> Cl2 + 2e

chemistry
If you are talking about HNO3, nitric acid, a suitable procedure is to bubble gaseous N2O5 into distilled water until saturation is achieved.

Chemistry
If you will show what you did perhaps we can find the problem. Other than guessing, however, we don't know what you've done.

Chem
You don't give enough information to know if you want the Eocell for a spontaneous or non-spontaneous cell. I assume you want the spontaneous reaction. Al(s) ==> Al^3+ + 3e Eo = +1.66 Fe^2+ + 2e ==> Fe(s) Eo = -0.440 -------------------- 2Al + 3Fe^2+ ==> 2Al^3+ + ...

Chemistry
dGorxn = (n*dGo formation products) = (n*dGo formation reactants)

Chemistry
mols AgNO3 = grams/molar mass = approx 0.06 but that's only an estimate as are all of the other calculations I do here. mols NaCl = M x L = approx 5E-4 .......NaCl + AgNO3 ==> AgCl + NaNO3 I......5E-4......0........0......0 add...........0.06.................. C.....-5E...

Chemistry
You want 15 g CaCl2. You will need 15 g CaCl2 x [(molar mass CaCl2.2H2O/molar mass CaCl2)] = ? g CaCl2.

chemistry
It may be possible depending upon how many other metals have specific heats close to the unknown metal. In any case, however, you probably can narrow the choice to one of a few and more importantly you can eliminate many metals.

Chemistry
I see a problem below that has been answered by Mathmate that isn't the same problem as this one. This one doesn't allow water to be added and both of the solutions available are more concentrated than the final desired one. I don't think this one is possible.

Chemistry
This can be done?? If you use 2L of the weaker solution of 150g/L and zero L of the more concentrated solution, then you have 300g/2L and that is too concentrated.

Chemistry
I don't believe this can be done with the data listed. I think at least one equation is missing.

chemistry
A catalyst lowers the activation energy

Chemistry
2.07L, yes.

Chemistry
(V1/T1) = (V2/T2) Remember T must be in kelvin.

Chemistry
To find pH for each equivalence point. For HNO3 + NaOH ==> NaNO3 + H2O That is a strong acid vs a strong base. Neither Na^+ nor NO3^- is hydrolyzed; therefore, the pH at the equivalence point is just that of pure H2O which is 7.0. For NaOH + HCN ==> NaCN + H2O The CN^- i...

Pages: <<Prev | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | Next>>

Search
Members