Thursday
September 18, 2014

Posts by DrBo222


Total # Posts: 41

chem
(P1V1/T1) = (P2V2/T2) Don't forget T must be in kelvin.
February 27, 2013

general chemistry
The breath, largely CO2. has a lower density than water.
February 27, 2013

ap chemistry
#2 should be right. Ka for HOCl = about 3E-8 Ka for HOBr = about 3E-9 Ka for HOI = about 3E-11
February 27, 2013

general chemistry College
The only one that has CO2 IN IT is Na2CO3.
February 27, 2013

general chemistry College
See your other post.
February 27, 2013

chemistry
Use the dilution formula. c1v1 = c2v2 2.09*v1 = 0.69*1.14 Solve for v1
February 27, 2013

Chemistry calorimeter.. please help!
Mg + H2SO4 ==> MgSO4 + H2 qrxn = mass H2O x specific heat H2O x (Tfinal-Tinitial) per gram is qrxn/2.16 g Mg. per mol Mg is (qrxn/2.16) x molar mass Mg
February 27, 2013

Chemistry
Le Chatelier's Principle says that a system in equilibrium will try to undo what we do to it. When volume is reduced that means pressure must be increased so the system will shift to the side with the fewer mols of gas. In this reaction there are 4 mols gas on the left and...
February 27, 2013

Chem
a. mols NaOH = grams/molar mass = 26.9/40 = about 0.67 and that divided by 0.5 = about 1.35M pH = -log 1.35 pH = -(0.13) = -0.13 approximately. Remember 1.0M = zero pH. b. And it is that simple. It's that negative pH again. HI = 1.62M (H^+) = 1.62M pH = -log(1.62) = about...
February 27, 2013

chemistry dilution
This is a confusing problem. Here is another approach. We have a soln that is 200 ug/mL. We want 3 ug/100 uL. That is 0.003 ug/uL = 3 ug/mL Say we want to make 100 mL of this solution, then 3 ug/mL x 100 mL = 300 ug we need. 200 ug/mL x ?mL =300 ug ?mL = 300/200 = 1.5 mL; ...
February 27, 2013

Chemistry
Do you want Kp or Kc. You can calculate Kc without changing to atm.
February 27, 2013

Chem
But if you must calculate it I would do this. 2H2O ==> H3O^+ + OH^- (H3O^+))OH^-) = K\w = 1E-14 (x)(x) = 1E-14 x = sqrt(1E-14) = 1E-78 pH = 7
February 27, 2013

Chem lab last question!! Urgent help
delta T = i*Kf*molality Plug in 3.9 for delta T, i = 2 for NaCl (i - 1 for urea), Kf, and solve for molality. molality = mols/kg solvent. You have m and kg solvent(convert 1000 lb to kg) and solve for mols. mol = grams/molar mass. You have mols and molar mass; solve for grams...
February 27, 2013

Chemistry
Looks good to me.
March 22, 2012

Chemistry honors
Use PV = nRT and solve for n = number of moles. Then n = grams/molar mass and solve for grams. Convert to mg. Remember to convert V to liters, T to kelvin, and p to atmospheres.
March 22, 2012

chemistry
mols NaOH = M x L = ? mols HCl = mols NaOH g HCl = mols HCl x molar mass HCl %HCl = (g HCl/mass sample) x 100 = ?
March 22, 2012

chemistry
mols KOH = M x L = ? mols HCl = mols KOH M HCl = mols HCl/L HCl.
March 22, 2012

chemistry
You want me to work the parts you've already worked. Show what you've done and we can tell you what to do next.
March 22, 2012

CHEM
You stopped too soon. 0.88 is the mole fraction of water. Multiply that by the normal vapor pressure of water (23.8) to obtain 20.87 which rounds to 21 mm.
September 16, 2010

gr.12 chemistry
I found other sites but they won't post either so I suppose we must be satisfied with what I have given you. Let me know you need more help. I can describe it in more detail if you tell me what you don't understand.
February 11, 2010

gr.12 chemistry
I found two sites that show the structures but I could not post them. Here is another one showing the trans isomer. Its at the bottom of the page. I'll look for another one for the trans isomer and post it if I can find one.
February 11, 2010

gr.12 chemistry
We can't draw structures on this board. If you want to draw a straight line formula, it would look something like this: C-C=C-C-C-C-C (You can add the H atoms) On carbon 2(from the left) AND on carbon 3, place the two H atoms on the same side (say on top) for the cis ...
February 11, 2010

chemistry
I gave you a web page when you posted this question earlier.
February 11, 2010

chemistry
Answered above several times.
February 11, 2010

science
See answers above by Bob Pursley and DrBob222
February 11, 2010

chemistry
I think A is the correct answer as it gives the heat of formation for one mole. D gives the heat of formation for two moles.
February 11, 2010

chemistry
What do you have available? You can get at this two or three ways. Do you know the side, a, for them? Then volume of unit cell = a3 for both BCC and FCC. For volume of atoms, look up the formula for volume of a sphere. I think it's (4/3)*pi*r3. For BCC, multiply that by 2 ...
February 11, 2010

Organic Chemistry
I assume the anion is C2H3O2^- which I expect means acetate ion. That is a strong base and reacts with phOH to give HC2H3O2 + phO^-; acetic acid and phenoxide ion. The double bonds in the benzene ring do NOT open. NOTE: This is the same KIND of reaction as the hydrolysis of ...
February 11, 2010

chemistry
The problem tell you 50.0 g H2O, which is 0.050 kg.
February 10, 2010

chemistry 21
Convert 0.540 kg Cu2S to moles. Moles = grams/molar mass. Using the coefficients in the balanced equation, convert moles Cu2S to moles Cu metal. Now convert moles Cu metal to grams. grams = moles x molar mass. This is the theoretical yield. % yield = (0.140 kg/theoretical ...
January 31, 2010

chem
1.25 x molar mass = grams. mass in grams = volume x density. Solve for volume.
January 31, 2010

chemistry
Doesn't it depend upon the amount of water you intend to use or the amount of solution one needs? (It does.) So molal = # moles/kg solvent. If you want 1 kg solvent, one needs 2.00 moles and that is 40.0 g. So 40.0 g NaOH/1.00 kg water makes a 2.00 m solution.
January 30, 2010

Chemistry
That is, by far, the simplest.
January 30, 2010

Chemistry
yes
January 30, 2010

Chemistry
yes.
January 30, 2010

Chemistry
I don't know how that screwball title got in but the post of how to work the problem is correct.
February 1, 2009

= a1 + a2 + a3
q1=heat to change T of solid from -40 to -10. q1 = mass x specific heat solid x (Tf-Ti) where Tf is final T (-10) and Ti is initial T = -40 C. q2=heat to melt the solid at -10 C to a liquid. q2= mass x heat fusion. q3 = heat to change T from -10 to 70. q3 = mass x specific ...
February 1, 2009

Chemistry
double post. See my response to your first post.
February 1, 2009

Chemistry
Did you do this experiment or are you trying to dry lab it? If you did it the questions should be easy to answer. If you are trying to dry lab it (by getting answers) and never doing the experiment, I won't help.
February 1, 2009

chemistry
Dalton's law of partial pressure says that the total pressure is the sum of the partial pressures of each gas.
February 1, 2009

chemistry
delta T = Kf*m m = mols/kg solvent mols = g/molar mass. If delta T is too large, molality will be to large. If molality is too large, mols will be too large. If mols is too large, then molar mass will be too small.(from molar mass = g/mols).
February 1, 2009

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