Thursday
December 18, 2014

Posts by DrBob222


Total # Posts: 46,131

chemistry
Cu3(PO4)2(s) + H2O==> 3Cu^2+(aq) + 2PO4^3-(aq) Ksp = (Cu^2+)^3(PO4^3-)^2
December 11, 2014

chemistry
1 mol H2 = 2.0g; 3 mols H2 = 6.0g = 0.006 kg. ? kJ = 210 kJ x (1000 kg/0.006 kg) = ?
December 11, 2014

science: question
Specifically, autoclaving is a method for sterilizing equipment under pressure at 121 degrees C for 15-20 minutes. You can Google "autoclaving" for more information. I have seen this done by dentists for natural teeth that are to be re-inserted as part of the dental ...
December 11, 2014

Chemistry
This may not help much but it's all I could find. http://en.wikipedia.org/wiki/Benzene#mediaviewer/File:Benzene_Representations.svg
December 11, 2014

Chemistry
Use PV = nRT and solve for n = number of moles at the conditions listed. For p you must use ptotal = pH2 + pH2O ptotal = 745 mm pH2O = 19.8 mm from the problem. Solve for pH2 (which is dry H2), then remember to convert to atm. 760 mm = 1 atm. When you have n, that's mols ...
December 11, 2014

Chemistry
Dissolving NH4Cl in H2O is an endothermic solution process. You measure how much it cools the solution by the temperature of the H2O. q = mass H2O x specific heat H2O x (Tfinal-Tinitial) The q you measure is for 3.2g/53.4g or q/0.0599 mol. You want to convert that to q/1 mol. ...
December 10, 2014

Science tech
https://ph.answers.yahoo.com/question/index;_ylt=A0LEViROColURaEA7u0PxQt.;_ylu=X3oDMTByNW1iMWN2BHNlYwNzcgRwb3MDNwRjb2xvA2JmMQR2dGlkAw--?qid=20070917042651AAuHwBT
December 10, 2014

Chemistry
1 mol contains 6.022E23 molecules so 0.923 mol will contain ........?
December 10, 2014

Urgent chemistry help
I don't understand these. The answer to the last one is that the subscripts change as the valences change.
December 10, 2014

Chemistry
The easy way to do this is not the easy way to explain it. I will do it both ways. The easy way to explain first. The density under the conditions listed is g/L = 0.371/1.97L = 0.188 g/L. The general gas equation can be modified for density as PM = dRT where M is molar mass ...
December 10, 2014

science
I think you're on target. http://en.wikipedia.org/wiki/Shale
December 10, 2014

science
or here. https://answers.yahoo.com/question/index;_ylt=A0LEVoCV3ohUHlYAbeAPxQt.?qid=20080801225715AA1BAq2
December 10, 2014

pharmaceutical math
You want to dilute the 30% cream by a factor of 3 so if you take 60 g of the 30% stuff and add cream base (120g) you should have it. c1v1 = c2v2 180*10 = 30*v2 v2 = 180*10/30 = 60 g of the 30%.
December 10, 2014

Science
You need balance and something to measure the volume.
December 10, 2014

Science
Floating is easier in the ocean because that is salt water and it has a higher density than fresh water.
December 10, 2014

Chemistry
I don't think this is exactly an isotonic solution but the answer to your question is that a 5.00 (mass/mass) solution of glucose contains 5.00 g glucose/100 g solution. Note: I don't know the density and it may be that the density of the solution may correct it to be ...
December 10, 2014

chemistry
1. Cu + 2Ag^+ ==> 2Ag + Cu^2+ 2. mols Cu = grams/molar mass = approx 0.03 BUT that's an estimate and you should do it more accurately. mols Ag = twice mols Cu = approx 0.06 ........CH3COOAg ==> CH3COO^- + Ag^+ I.........solid.......0..........0 C.........solid..........
December 10, 2014

pharmaceutical calculations
I don't see a question here.
December 10, 2014

chemistry
Your problem is delta T. That's Tfinal-Tinitial. For the water your 3.1 is correct. Tf is 25.4 and Ti is 22.3 and dT is 3.10. But that isn't right for the Ni. Tf is 25.4 and Ti is 95.0. dT is not 3.10.
December 10, 2014

chemistry
No, I don't obtain that. If you post your work I will find the error.
December 10, 2014

Chemistry
(n1/v1) = (n2/v2)
December 10, 2014

Chem
See your other post.
December 10, 2014

Chem
PV = nRT
December 10, 2014

Science~!
1 is b 2 density = mass/volume 3 melting point, boiling point, solubility in water are all physical properties.
December 10, 2014

chemistry
1. I don't see a molar absorptivity constant nor any information to calculate same. 2. Please clarity if that A = 0.540(you have 0.549 in your calculation) is the amount in 0.5 mL or the amount in the 2mL. The way the problem reads to me is confusing; i.e., I don't ...
December 10, 2014

chemistry
heat lost by Ni + heat gained by H2O = 0 [mass Ni x specific heat Ni x (Tfinal-Tinitial)] + [mass H2O x specific heat H2O x )Tfinal-Tinitial)] = 0 Substitute and solve for the only unknown, mass Ni.
December 10, 2014

Chem.
It does not produce OH^- in solution.
December 10, 2014

Chemistry 2!
Kc = (C2H5OH)/(H2O)(C2H4)
December 10, 2014

Chemistry 2!
Substitute (C2H4) and (C2H5OH) and Kc into the Kc expression and solve for (H2O)
December 10, 2014

chemistry
Here is the way this works. At the beginning of the titration you have a mixture of CO3^2- + HCO3^-. When you titrated with the first 17 mL you don't touch the HCO3^-; you titrate all of CO3^- halfway. That is CO3^2- + H^+ ==> HCO3^-. With that information you can ...
December 9, 2014

chemistry
Why guess? Work it out. dHrxn = (n*dHf products) - (n*dHf reactants)
December 9, 2014

chem
Please note that you didn't get too different answers here. My response gives rate of fastest = 1.05 x slowest. Bob P gave rate slowest = 0.949 x rate fastest. Also note that 1/1.05(4) = 0.949
December 9, 2014

chem
The fastest will be Ar36; the slowest will be Ar40. (rate 36/rate 40) = sqrt(40/36)
December 9, 2014

chemistry
2C + 3H2 + 1/2 O2 --> C2H5OH dH = -238.7 kJ/mol. Doesn't - tell you that heat is released. That makes the answer D.
December 9, 2014

Chemistry
Yes, I think you're making it tougher than it is. You have an error in mols of NaHCO3. grams NaHCO3 = 1.5/2 = 0.75 mols NaHCO3 = 0.75/84 = 0.0089 Then M = mols/L. You know M = 1E-4 and you know mols = 0.0089 so L = 0.0089/1E-4 = 89 L. If you carry all of the digits that is...
December 9, 2014

Chemistry
In all of my years in the field of chemistry I have never heard of electrons having addresses. However, I would think the answer to your question is 3S1/2
December 9, 2014

Chemistry
pros and cons: https://answers.yahoo.com/question/index;_ylt=A0LEV7oydYdU_igAYh0PxQt.;_ylu=X3oDMTByMG04Z2o2BHNlYwNzcgRwb3MDMQRjb2xvA2JmMQR2dGlkAw--?qid=20080615210840AAKraO2 cons: https://answers.yahoo.com/question/index;_ylt=A0LEVvGcdYdURlIA5pcPxQt.?qid=20080531154353AARHrVw
December 9, 2014

chemistry
The modified gas formula is P*molar mass = density*RT. Solve for M (to determine the molar mass), and using that number substitute back into PM = dRT with the new conditions and calculate the new density. There are others ways to do this but this is the easiest way to explain ...
December 9, 2014

Chemistry
There are three equations that handle all of these situations. Equation 1 is for WITHIN a phase, q = mass x specific heat x (Tfinal-Tinitial). Example. For the liquid phase of water from zero C to 25 C, then q for that part is q = (48g x 4.184 J/g*C x (25-0) = ? Equations 2 ...
December 9, 2014

chemistry
(P1V1/T1) = (P2V2/T2)
December 9, 2014

chemistry
You have two equations. pH = pKa + log(base)/(acid) Substitute and solve fr base/acid. Calling base = b and acid = a, you will get a ratio of b/a = ?, This is equation 1. equation 2 is a + b = 3.0E-3 Solve the two equations simultaneously for a and b = (acid) and (base) note:(...
December 9, 2014

science
Yes, C is the correct answer and it's because c = freq*wavelength. So if frequency goes up, wavelength goes down.
December 9, 2014

Analytical Chemistry
One factor worth remembering is 1 ppm = 1 mg/L. Convert 2.91g Na3PO4 to g Na. That is 2.91 g Na3PO4 x (3*atomic mass Na/molar mass Na3PO4) = ?. You have ? g Na^+ in 2.33 L. That is (? g Na^+/2.33 L solution) = ? g Na/L; now convert ?g/L to ?mg/L.
December 9, 2014

Chemistry
t1/2 = 1/ak[A]o Substitute 0.27 for [A]o. The reaction is not given; usually in those circumstances a is assumed to be 1.
December 9, 2014

chemistry
Your post contains too many strange symbols. See if you can correct the post.
December 9, 2014

Organic Chemistry
How many mols of the tetraphenylporphin do you have? That's mols = M x L = ? Since the ratio is 1:1 you have that same number of mols Cu^2+ and the same number of mols of CuCl2. Then mass CuCl2 = mols CuCl2 x molar mass CuCl2.
December 9, 2014

Chemistry
You have some strange symbols which I assume was supposed to be an arrow. I've corrected it. Do you mean [N2O4] = 0.800M at equilibrium? or initially? I'll assume at equilibrium. ...........N2O4(g) ==> 2NO2(g) Kc = (NO2)^2/(N2O4 0.200 = (NO2)^2/(0.800. Solve for (NO2).
December 9, 2014

chemistry
The number of protons with 1+ charge = the number of electrons with a 1- charge. Say you look at Na, atomic number 11 so it has 11 protons and 11 electrons. 11+ + (-11) = 0
December 9, 2014

Chemistry
Use the same procedure as for Sean (by the way it is easier for us if you stick to the same screen name). mols = grams/molar mass and m = mols/kg solvent Substitute and solve for delta T. Remember new freezing point is 0-delta T.
December 8, 2014

Chemistry
delta T = i*Kb*m i = van't Hoff factor i = 1 for glucose i = 2 for KF Take a look at the formula. For the same m and the same Kb, the only difference is i. So i*Kb*m must be a greater number for which one. And the greater number for delta T + 100 (the normal boiling point ...
December 8, 2014

chemistry
I worked one just like this earlier. Here is the link. http://www.jiskha.com/display.cgi?id=1418084714
December 8, 2014

chemistry
1. Write and balance the equation. 3Fe + 2O2 ==> Fe3O4 2. Convert grams O2 to mols. mols = grams/molar mass = ? 3. Using the coefficients in the balanced equation, convert mols O2 to mols Fe3O4. That's ?mols O2 from step 2 x (1 mol Fe3O4/2 mols O2) = ? mols O2 x (1/2...
December 8, 2014

Chemistry
Charge density is the charge/unit volume. Since Mg^2+ ion is smaller than the Ba^2+, the Mg will have the greater charge density; i.e., a 2+ charge spread over a smaller volume.
December 8, 2014

Chemistry
C = K*p C = (0.0015 mol/L*atm)*0.0093 = ? M.
December 8, 2014

chemistry
See your other post.
December 8, 2014

chemistry
Convert 3.00 C2H6 to mols H2O. That's 3.00 x (6 mol H2O/2 mols C2H6) = 9.00 mols H2O Do the same for mols O2 to mols H2O. That's 9.00 x (6 mols H2O/7 mols O2) = 7.71 mols H2O. In limiting reagent problems the smaller number is ALWAyS the correct choice; therefore, O2 ...
December 8, 2014

Chemistry
Write the equation. We can't draw structures on this forum but let's call salicylic acid SA, acetylsalicylic acid as ASA, and I know the reaction is 1:1. Therefore, SA --> ASA mols SA = grams SA/molar mass SA = ? mols ASA = mols SA since it is 1:1 Then g ASA = mols ...
December 8, 2014

Science
I don't know how to answer your question. Part of it depends upon what system you are using for the periodic table, part on if you are using the short form or the long form (probably long since the short form hasn't been used in several years), and part on how the ...
December 8, 2014

Chemistry
That looks ok to me.
December 8, 2014

Chemistry
mols CaC2O4.H2O = grams/molar mass = 0.6914 g/molar mass CaC2O4.H2O 1 mol CaC2o4.H2O = 1 mol H2C2O4 so multiply mols CaC2O4 x molar mass H2C2O4
December 8, 2014

Chemistry
I wonder if you meant CO2 instead of C. T must be pretty high to have C has a gas. Total mols = sum mols of each gas. Then XO2 = nO2/total mols XH2 = nH2/total mols XC = nC/total mols. Then pO2 = XO2*Ptotal = ? pH2 = XH2*Ptotal pC = XC*Ptotal
December 8, 2014

chemistry
You really should find the caps key on your keyboard and USE it. pH = -log(H^+). Substitute and solve for (H^+). Then (H^+)(OH^-) = Kw = 1E-14. Substitute and solve for OH^-. Neutral is pH = 7 acid is pH < 7 basic is pH > 7
December 8, 2014

Chemistry
I believe both of you are confused. HCl + NaOH ==> NaOH + H2O mols HCl = M x L = ? mols NaOH = M x L = ? You go through the math above and find HCl is greater mols than NaOH by 0.001 Then (HCl) = mols/L = 0.001/0.110
December 8, 2014

Chemistry Help!!
Theresa, what's the problem you're having with these? The first two look balanced to me.
December 8, 2014

square feet math
length x width = area 14 x w = 70 Solve for w.
December 8, 2014

Chem
Do you have a question?
December 8, 2014

O Chem
http://www.jiskha.com/display.cgi?id=1418016978
December 8, 2014

Organic Chemistry
We are not able to draw structures of any kind on this forum and certainly not curved arrows.
December 8, 2014

chemistry
1.30 M x (63 mL/248 mL) x [124 mL/(124+173)] = ? M
December 7, 2014

chemistry
Like a lot of questions this one is not well thought out. Did the solution boil? I'm assuming it did not. Then I would answer b. If it boiled for a very short time there are two answers, b and a
December 7, 2014

Chemistry; stoichiometry
Using your numbers I obtained 1.0804 g which rounds to 1.080 g Ag to 4 significant figures. I suspect you first calculated mols Cu = 0.3180/63.5 and read that number, then multiplied by the rest of the equation. I leave my numbers in the calculator and do the calculation all ...
December 7, 2014

chemistry
I know this sounds stupid but it is called a tracer when it traces. For example, in the reaction CH3COOH + HOCH3 --> CH3COOCH3 + H2O we would like to know which H and/or which O atoms are involved. It could be the EITHER O on the CH3COOH or the O on the HOCH3. So what we do...
December 7, 2014

Chemistry
Use PV = nRT and solve for n = number of mols. Then n = grams/molar mass. You know mols and grams, solve for molar mass.
December 7, 2014

Chemistry
g epsom salt = 2.00 x 0.61 = 1.22g MgSO4. g H2O = 2 x 0.39 = 0.78 mols MgSO4 = 1.22/120.4 =0.0101 mols H2O = 0.78/18 = 0.0433 Now find the ratio H2O molecules to 1 molecule of MgSO4. 0.0101/0.0101 = 1.00 0.0433/0.0101 = 4.29 Actually, that 0.29 is too much to throw away and I ...
December 7, 2014

Chemistry
1.225 g CuSO4 x (atomic mass Cu/molar mass CuSO4) = ? In reality that CuSO4 probably was CuSO4.5H2O.
December 7, 2014

chemistry. please help drbob222
http://www.jiskha.com/display.cgi?id=1417920941
December 7, 2014

chemistry
1 mol Ni contains 6.022E23 Ni atoms. mols Ni = (4.3E15/6.022E23) = ? Then 1 mol Ni has a mass of about 58.7 g; therefore, ? mols Ni x 58.7 g/mol = ? g Ni.
December 7, 2014

Chemistry
Two equation solved simultaneously. You follow. Let x = mass Na2CO3 and y = mass K2CO3 ---------------------- equation 1 is x + y = 1.00 g That's the easy one. What you do for equation 2 is to say mols CO3^2- from Na2CO3 + mols CO3^2- from K2CO3 = 8.50E-3 mols CO3^2-. Now ...
December 7, 2014

chemistry check if my answers are right. drbobzz
a and c are right now but on c you have an answer to too many significant figures. The 48.0 limits the answer to 3 s.f. so you should round that 33.22 to 33.2 grams for mass H2O.
December 7, 2014

chemistry check if my answers are right. drbobzz
Thank you for posting your work. It makes it so much easier to catch the error and it let's me know about basic problems you may have. For A you have done everything exactly right except the last step. The molar mass of oxygen is 32 since it is O2 and not O and the correct...
December 7, 2014

chemistry check if my answers are right. drbobzz
B is right; A and C are not. If you will post your work I will find the error and correct.
December 7, 2014

chem
1 mol of a gas at STP occupies 22.4L
December 7, 2014

Chem-Diprotic Acid
This is done just like a monoprotic acid but just do one acid at a time and reason it through. The pH is 3.8 so what is (H^+)? pH = -log(H^+) so (H^+) is about 1.6E-4 ............H2A ==> H^+ + HA^- I..........0.75..1.6E-4...0 C...........-x......x......x E.........0.75-x. 1...
December 7, 2014

ilays high school
You should repost and make sure your post makes sense. What in the world is 25 cent meter cubic of 2 mol Na2CO3?
December 7, 2014

Chemestry
"take the 'date' in percent" makes no sense to me.
December 7, 2014

chemistry
mols acetic acid = grams/molar mass = ? Then M acetic acid = mols/L solution. You know M and mols, solve for L.
December 7, 2014

Chemistry
delta T = Kf*m. Substitute and solve for molality = m m = mols/kg solvent Substitute and solve for mols. mols = grams/molar mass. You have mols and grams, solve for molar mass.
December 7, 2014

chemistry
mols Cu2O = grams/molar mass = ? mols Cu2S = grams/molar mass = ? Using the coefficients in the balanced equation, convert mols Cu2O to mols Cu. Do the same for mols Cu2S to mols Cu. It is likely these two values will not be the same; in limiting reagent problems the smaller ...
December 6, 2014

college gen chem
I don't know how advanced this class is but there is an easy way (and not quite so accurate) and a harder way (but a little more accurate). Easy way. You start with 100 atoms U and they decay over the years to form x atoms Pb which leaves 100-x atoms U. The ratio of Pb/U ...
December 6, 2014

chemistry PLEASE HELP!!!
http://www.jiskha.com/display.cgi?id=1417883669
December 6, 2014

chemistry
Is this the equation? ........CO + H2O ==> H2 + CO2 E.......300..150.....90....300 Substitute into Kp expression and solve for Kp. I get 0.6. Then x = pCO added. .........CO + H2O ==> H2 + CO2 old E....300..150.....90....300 add......x..................... new E...
December 6, 2014

chemistry
Isn't that 2. The 5 d orbitals are divided into the dx^2-y^2 and dz^2 at the top energy level and the dxy dxz and dyz orbitals at the bottom.
December 6, 2014

chemistry
You can see from the site below that [Pd(CO)4]^2+ is square planar; probably this is dsp2 also. Its structure with two ionizable Cl^- ions would be [Pd(NH3)4Cl2]Cl2. The palladium carbonyl complex was the closest I could come on the web. http://papadantonakis.com/images/b/b7/...
December 6, 2014

Chemistry
dG = dH - TdS dG = -93 - 356(-0.198) = ? If - it's spontaneous?
December 6, 2014

chemistry
I suppose true but destruction also is caused by the fire.
December 6, 2014

chemistry
An anion has a - charge. Example 9 electrons = -9 charge 9 protons = +9 charge ------------------------- neutral atom = 0 charge So to make an anion, one must have (more/fewer) protons.
December 6, 2014

chemistry
Na2O + 2H2O ==> 2NaOH
December 6, 2014

chemistry
The PRODUCTS will not be acid or basic BUT the SOLUTION will be acidic sometimes and basic sometimes and neutral sometimes.
December 6, 2014

chemistry
Of course not
December 6, 2014

Chemistry
Generally increasing the number carbons increases the boiling point.
December 6, 2014

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

Search
Members