Wednesday
April 16, 2014

Posts by DrBob222


Total # Posts: 41,743

Chem 2
What I meant was that Kf for camphor is 37.7 celsius/m or 37.7 Kelvin/m

Chem 2
You can but it doesn't matter. I think Kf for camphor is about 38 C/m (37.7 maybe?) or something like that.

Chem 2
I think I answered your question. The easy way to find the error is for you to post your work and let me check it. I'm happy to do that for you.

organic chemistry
It hydrolyzes in air, particularly if the air is very humid, to produce CH3COOH (acetic acid which is the vinegar smell).

Chemistry
..........H2SO4 ==> H^+ + HSO4^- I........0.0050M....0......0 C.......-0.005...0.005...0.005 E..........0.....0.005...0.005 So for the first ionization, H^+ = 0.005M and HSO4^- = 0.005M. Then HSO4^- goes through k2. ........HSO4^- ==> H^+ + SO4^2- I.....0.005M....0.005.....

chemistry
What is reaction of medium? NH4^+ + 2H2O + NO2^-==> NH3 + H3O^+ + HNO2 + OH^- and you can combine the H3O^+ and OH^- on the right to form 2H2O, then cancel the 2H2O on the left to leave you with NH4^+ + NO2^- ==> NH3 + HNO2

Chemistry
Google it. Go to Google, type in "3.00E10 cm/s to km/hr" without the quotation marks and hit the enter button.

Chemistry
3.271E-22 g Au/atom x #atoms = 5.00 g. Solve for # atoms.

Chem Check Please!!!
1. Check your data. I don't think the Ka values are correct.I might believe 7.3e-10. And is that 7.3 or 7.4? 2. I don't believe the quadratic formula must be used. 3. Finally,I don't believe the calculation for the quadratic formula.

Chemistry
dm^3 x (10 cm/dm)^3 = ? cc = ?mL

Chemistry
PV = nRT and solve for n = number of mols. Then 1 mol contains 6.022e 23 molecules.

Chemistry
P*molar mass = density*RT

chemistry
mols K3PO4 = grams/molar mass mols H2O = grams/molar mass Total mols = ? XK3PO4 = ? XH2O = ? NOTE. Remember i, the van't Hoff factor for H3PO4 is 3and take that into account in the above, or at least before calculate ing vapor pressure.

Chemistry
What's HNO3-? HNO3 must be zero H2O must the the largest? NO3^- must be 1E-6?

Chem
There is no BaOH2. You must mean Ba(OH)2 Ba(OH)2 ==> Ba^2+ + 2OH^- 4.93 mg/L = 0.00493 g/L. mols/L = M = 0.00493/molar mass Ba(OH)2 1 mol Ba(OH)2 gives 2 mols OH^- Therefore, M OH^- must be twice M Ba(OH)2. Then pOH = -log(OH^-) and pH + pOH = pKw = 14. You know pOH and pKw...

Chemistry 2
mols NaOH = grams/molar mass M NaOH = mols/L solution M OH^- = M NaOH pOH = -log(OH^-) pH + pOH = pKw = 14.

Chemistry
C5H12 + 8O2 ==> 5CO2 + 6H2O C12H24 + 18O2 ==> 12CO2 + 12H2O volume CO2 from pentane = 10cc x (5 mols CO2/1 mol C5H12) = 50 cc CO2. mols dodecene = 0.084/molar mass = approx 5E-4. You should confirm ALL of these calculations since I've estimated here and there. mols C...

Chemistry 2
I thought I did one like this for you yesterday. Add M and solve for pH. Both are strong acids.

Chem
HCO3- + HF ==> H2CO3 + F^- ==> CO2 + H2O + F^-

Chem
HPO42-+H+<--> H2PO4^- HPO42-+OH-<--> PO4^3- + H2O

Chemistry 2
I don't get it. You have no numbers for #1 while you list kP for 2 and 3.

college chemistry
2 atoms/unit cell mass unit cell = 85.47*2/6.022e23 =? volume = mass/density = ? a^3 = volume Solve fora. Then 4r = a(3)^1/2 Solve for r.

Chemistry
Add eqn 1 to eqn 2 to obtain A+2B ==> 2C 2C ==> D ------------ A + 2B ==> D so K' = k1*k2. You want the reverse of this rxn; therefore, you want 1/K'.

Chemistry
Didn't I do one like this for you yesterday. c1v1 = c2v2 c = concn v = volume 5*200 = 2*mL mL = total volume.

Chemistry
Write the K expression. Now, to have K 7.0 (greater than 1.0), must products or reactants be greater or less?

Chemistry
q = mass x heat fusion.

chemistry
q = mass x heat fusion

Chemistry
Your second problem is a limiting reagent (LR) problem. You know it is a LR problem because amounts are given for BOTH reactants. You do these just like simple stoichhiometry problem BUT do it for EACH reagent then take the smaller amount formed as the product formed. Convert ...

Chemistry
mols AgNO3 = M x L = ? Using the coefficients in the balanced equation, convert mols AgNO3 to mols NaCl. Now convert mols NaCl to grams. g = mols x molar mass.

chemistry
CuCl2 + 2NaNO3 ==> 2NaCl + Cu(NO3)2 mols CuCl2 = grams/molar mass Using the coefficients in the balancaed equation,convert mols CuCl2 to mols NaCl formed. Convert mols NaCl formed to grams. g = mols x molar mass. This is the theoretical yield (TY). The acuual yield (AY) is ...

Chemistry
To keep the can from exploding due to increased pressure from the heating.

chemistry
mols NH3 = grams/molar mass A. Convert mols NH3 to mols F2 using the coefficients the balanced equation. ?mols NH3 x (5 mols F2/2 mol NH3) = ? mols F2. Then convert mols to grams. g F2 = mols F2 x molar mass F2. B. and C. are done the same way.

Chem 2
delta T = Kf*m Substitute and solve for m = molality. m = mols solute/kg solvent Substitute and solve for mols solute mols = grams/molar mass. You have grams and mols, solve for molar mass.

Chem 2
pi = nRT Substitute and solve for n = mols Then M = mols/L solution # mols = M x L = ? molar mass = grams/mols.

chemistry
mols HCl = M x L = ? mols NaOH = mols HCl Then M NaOH = mols NaOH/L NaOH

Chemistry help
1/wavelength = R(1/1 - 1/x^2) wavelength = 93.77E-9 m Solve for x = where the electron has been promoted. Then 1/wavelength = R(1/y^2 - 1/x^2) x is the value from the first part of the problem. y is the new level where the electrons finishes its journey. R = Rydberg constant =...

additional---AP Chemistry
After (SO2) in M, then mol = M x L Then mols = grams/molar mass. Solve for grams.

AP Chemistry
You need to work out the concns. (SO3) = (1.11g/molar mass SO3)/2L = approx 0.007M but you need to do it more accurately as well as calculations that follow. They are estimates also. (O2) = 1.06/32/2L = approx 0.0015M Kc = (SO3)^2/(SO2)^2(O2) Substitute Kc and concns SO3 and O...

Chemistry
.........NH4^+ + H2O ==> NH3 + H3O^+ I........1E-3.............0.....0 C.........-x..............x......x E.......1E-3-x............x......x Ka for NH4^+ = (Kw/Kb for NH3) = (x)(x)/(0/001-x) Solve for x = (H3O^+). Then (H3O^+)(OH^-) = Kw = 1E-14 and solve for OH^-

Chemistry
No. You need to brush up on the difference between precision and accuracy. The students obtained 7.32 for a 2 g weight. That isn't very accurate at all or they would have obtained 2g wouldn't they? However. all of them obtained the same value of 7.32 so the precision i...

Chemistry
py + HBr ==> PyH + Br^- You know how many mols pyridine you started with. That's M x L = ? Now take M x L of the titrant to give yo mols HBr added. Since the reaction is 1:1 you know 1 mol HBr neutralizes 1 mol pyridine. Subtract mols py-mol HBr to see which is in exces...

Chemistry
You must take HF into consideration during the calculation. The whole point of these problems is to show you that BaF2 has a certain solubility in neutral solution. As the solution becomes more and more acid the formation of HF becomes more (because HF is a weak acid); that sh...

to abdul---chemistry
You should post your own question from the top of the page instead of piggy backing onto another.

chemistry
q to melt ice @ 0C to liquid H2O @ 0C. q to move T from zero C to 100 C q to change liquid at 100 to steam at 100.

Chemistry
What's the problem?

AP Chemistry
See your later post above.

Chemistry
Can't draw pictures. 6.0M x 500 mL = 2M x ?mL ? mL is the total volume needed.

Chemistry
3.6 x [750/(750-150)]= ?

chemistry
2.4 x (250/750) = ?

Chem
17 e.g., Cl with 7 dots around it. 15 e.g., N with 5 dots around it.

Chemistry
Zn is almost always 2 as its placement in the periodic table would suggest. Same for Sc at +3. All of the others are variable. At least ONE valence will be the period; for example, Mn has bunches of numbers but +7 is one of them. Cr has several but at least one of them is +6. ...

Chem
Does relative mean concentrations are not needed; only a ranking? You know H2O is the most prevalent. You know HNO3 is the least. Can you fill in the others. What are your thoughts and "I don't have a clue" is not acceptable.

Chemistry
HCl is a strong acid; i.e., it ionizes 100%. Same for HBr. So the combined M in the solution is 0.5+0.085. pH = -log(H^+), then pH + pOH = pKw = 14.

Chem
If we define "valence electrons" as simply the number of electrons in the outer shell of an atom, these can be found in the periodic table. Xe has 8, Rb has 1, I is 7, etc. Just look up the electron configuration of each.

Chemistry
Look at the equation. The equation tells you 1 mol CaO reacts with 1 mol H2O to yield 1 mol Ca(OH)2.

Chemistry
Your mistake is you didn't take into account the van't Hoff factor, i. The equation is delta T = i*Kf*m is for CsX is 2.

Chemistry
I agree with the last answer.

Chemistry
See your post above.

Is the Cations and Anions right?
No. None are completely correct. 1. Fe^3+ and SO4^2- 2. Co^2+ and 2Cl^- I don't understand your problem. Perhaps you cn explain it to me. For #2. when you write Co(II) you KNOW WITH CERTAINTY that Co is 2+. And if Co is 2+ and you have two Cl with it, then Cl must be -1 an...

Chemistry
E = hc/wavelength Substitute wavelength and solve for E = ? J/photon. 7 kJ/s/m^2 x 8.40 cm^2 x *(1 m/100 cm)^2 x (1 kJ/1000J) = Joules striking 8.40 cm^2 area. Then ? J/photon x # photons = J striking 8.40 cm^21 area. Solve for # photons.

Quick math help please!!!
You can tell if it is right or not by substituting your values for x and y into either equation. If you get -19 for the first one OR -30 for the second one your answers are right.

Chem
What you have is arranged properly. FeO difference in electronegativity is 1.7 and should fit between OH and NaCl. FeC difference is 0.7 and should fit after CH and before HCl.

College Chemistry
J = mass x specific heat x (Tfinal-Tinitial)

College Chemistry
See this. http://www.jiskha.com/display.cgi?id=1392734601

chemistry 112
For an 80% yield you will need 1.6 mols SO3. .........2SO2 + O2 ==> 2SO3 I........2 mols..2.......0 C........-2x.....-x......2x E.......2-2x.....2-x.....2x Then an 80% yield gives SO3 = 1.6 mol; therefore, 1.6 = 2x and x = 0.8 Solve for 2-2x = 0.4 mol SO2 2-x = 1.2 mols O2 ...

chemistry
Pick any convenient mass, say 100 g, then mass = volume x density Substitute and see which has the larger voluem.

chem
mols Li = grams/atomic mass Using the coefficients in the balanced equation, convert mols Li to mols H2. Use PV = nRT, substitute the conditions and mols and solve fr V in liters.

chemistry
You didn't list any but the ions present will be Na^+ and SO4^2-

chemistry
%O = 100 - %C - %H Take a 100 g sample which gives 53.4g C 11.1g H 35.5g O mols C = 53.4/12 = ? mols H = 11.1/1 = ? mols O = 35.5/16 = ? Now find the ratio of the atoms to each other (as whole numbers) with the smallest number being 1.00. The easy way to do that is to divide t...

AP Chem
The (H^+) for a weak acid/weak base salt is (H^+) = sqrt (KwKa/Kb). So you look up a Ka that is smaller than Kb. You know Kb is about 1.8E-5 so any acid that is smaller than that should produce a basic solution. Look in your Ka tables for an acid smaller than 1.8E-5 and if the...

chem 102
p = KcC p = 0.21 when saturated and Kc = about 769 atm*L/mol but you should look this up in your tables and use that number here. Also, I have estimated all of my other answers; you definitely should go through the calculations yourself and refine each of the steps. C for the ...

chemistry
mol CuSO4 = grams/molar mass M = mols/L solution.

Chemisty
1. Write and balance the equation. 2NaOH + H2SO4 ==> Na2SO4 + 2H2O 2. mols NaOH = M x L = ? 3. Using the coefficients in the balanced equation, convert mols NaOH to mols H2SO4. ? mols NaOH x (1 mol H2SO4/2 mols H2SO4) = ? mols H2SO4. 4. Now convert mols H2SO4 and volume to ...

Chemistry
q = mass(grams) x Hvaporization (J/g) This will give q in J/g, then change J to kJ.

chemistry
What units?

Chemistry
0.01M means 0.01 mols H3PO4/1000 mL solution. The molar mass is 98; therefore, there are 0.98 grams H3PO4/1000 mL solution. mass solution is 1000 mL x 1.11 g/mL = 1110 grams. mass % = (gH3PO4/g solution) = (0.98/1110)*100 = ? % w/w

Chemistry
Heating NaHCO3 to what temperature? If to about 270 C or so it is 2NaHCO3 ==> CO2 + Na2CO3 + H2O mols NaHCO3 = grams/molar mass Using the coefficients in the balanced equation convert mols NaHCO3 to mols CO2. Then 22.4L x ?mols = ? L at STP

Chemistry
How can we help you with this assignment short of doing your homework for you. I recommend color for Ni. The Al and Sn are colorless while most Ni solutions are green or blue. Co solutions are pink to blue. Remember that Al is amphoteric; i.e., it forms a white gelatinous ppt ...

chemistry
mols methanol = grams/molar mass Then m = mols/kg solvent

chemistry
You provided no information for the question. My crystal ball is hazy today.

Chemistry
CuSO4 + 2KOH ==> Cu(OH)2 + K2SO4 You have 150 x 1.50 = 225 millimols CuSO4 and 450 mmols KOH q = mass solution x specific heat x (Tfinal-Tinitia) I would use 300 mL = 300 g for mass soln. Specific heat H2O is 4.184 J/g*C Tfinal and Tinitial are given. q is Joules/225 mmols....

CHEMISTRY
I will do the first one in detail. The others follow the same pattern. Look up the activity series in your text/notes/Google/etc. If the METAL is above the metal ION, the metal will displace it; otherwise, there is no reaction. 3Mg + Al2(SO4)3 --> 3MgSO4 + 2Al Mg is ABOVE A...

Chemistry
See your post above. For oxidizing agent and reducing agent here is what you do. Oxdn is loss of electrons--that substance is the reducing agent. Reduction is the gain of electrons--that substance is the oxidizing agent.

chm101
high

CHEMISTRY
0.15g/molar mass = mols M = mols/6.5L pH = -log(HCl)

science
You have posted a number of these multiple guess questions recently; have you given any thought to telling us what you think the answer is and why you chose that answer.

chem
You don't give enough information about the question to be sure but I assume this is a 10 eletcron system with 2e in the n = 1 and 8e in n = 2. So out of the 10 possibilities, 2 of them are from the n = 1 shell (2/10) and 8 of them are from the n = 2 (8/10).

Chem Help :(
1. pH = -log(H^+) 2. (H^+)(OH^-) = Kw = 1E-14. You know Kw and OH, solve for H^+, then use pH equation in #1.

Chemistry
Mg + 2HNO3 ==> Mg(NO3)2 + H2 mols Mg = grams/molar mass mols Mg(NO3)2 = mols Mg (look at the mole ratio) which is 1 mol Mg to 1 mol Mg(NO3)2. Then grams Mg(NO3)2 = mols x molar mass. For HNO3 needed, convert mols Mg to mols HNO3 and convert mol HNO3 to grams as in the above.

Chemistry Help Please!!!
First you must recognize that k1 is the largest K of the group and the pH of the solution will be due largely to the first dissociation. The second and third don't produce enough to concern us too much. .......H3PO3 ==> H^+ + H2BO3^- I......0.05M.....0.......0 C......-x...

science
Does this last post have anything to do with the first? An object traveling in a straight line in space will continue in a straight line unless acted upon by an outside force.

science
I would go with D.

science
??

science
A

chemistry
??

science
B

Ap chem-Bases
I did this for you yesterday.

college chemistry
C = p*k k = C/p Convert 321.9 torr to atm. atm = torr/760 Convert 0.02538 g/L to mols/L = M mols = grams/molar mass Substitute into equation and solve for k.

chemistry
Larger and more complicated structures have more entropy than their lesser cousins. NaNO3 has more atoms, more bonds, higher molar mass, etc.

Chemistry
Solid phosphorus pentachloride yields phosphorus trichloride gas plus chlorine gas.

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