DrBo222

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.

16 years ago

Dalton's law of partial pressure says that the total pressure is the sum of the partial pressures of each gas.

16 years ago

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).

16 years ago

double post. See my response to your first post.

16 years ago

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...

16 years ago

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

16 years ago

yes.

15 years ago

yes

15 years ago

That is, by far, the simplest.

15 years ago

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 solu...

15 years ago

1.25 x molar mass = grams. mass in grams = volume x density. Solve for volume.

15 years ago

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 = (0.1...

15 years ago

See answers above by Bob Pursley and DrBob222

15 years ago

Answered above several times.

15 years ago

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.

15 years ago

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*r<s...

15 years ago

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 a...

15 years ago

The problem tell you 50.0 g H2O, which is 0.050 kg.

15 years ago

I gave you a web page when you posted this question earlier.

15 years ago

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)...

15 years ago

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.

15 years ago

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.

15 years ago

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.

15 years ago

Looks good to me.

13 years ago

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.

13 years ago

mols NaOH = M x L = ? mols HCl = mols NaOH g HCl = mols HCl x molar mass HCl %HCl = (g HCl/mass sample) x 100 = ?

13 years ago

mols KOH = M x L = ? mols HCl = mols KOH M HCl = mols HCl/L HCl.

13 years ago

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.

13 years ago

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...

12 years ago

(P1V1/T1) = (P2V2/T2) Don't forget T must be in kelvin.

12 years ago

The breath, largely CO2. has a lower density than water.

12 years ago

#2 should be right. Ka for HOCl = about 3E-8 Ka for HOBr = about 3E-9 Ka for HOI = about 3E-11

12 years ago

The only one that has CO2 IN IT is Na2CO3.

12 years ago

Use the dilution formula. c1v1 = c2v2 2.09*v1 = 0.69*1.14 Solve for v1

12 years ago

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

12 years ago

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 g...

12 years ago

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 = -...

12 years ago

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 =...

12 years ago

Do you want Kp or Kc. You can calculate Kc without changing to atm.

12 years ago

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

12 years ago