DrBob222

And many thanks for the thanks. All of us like to think that we offer a helping hand. Both individually and as a group I think this group does that. Good luck to you with your finals and I hope we see you when your next semester/quarter starts. And many t...

19 years ago

The exact question is: Benzyl alcohol (bp 205 degree C) was selected by a student to crystallize fluorenol (mp 153-154 degrees C) because the solubility characteristics of this solvent are appropriate. However, this solvent is not a good choice. Explain....

19 years ago

Does anyone know where I can get a free MSDS sheet WITHOUT giving my complete biography? I don't mind an email address and even a name but land mail address, phone number, number of adults in household, cars in household, fax number, and other garbage is...

19 years ago

As an interested bystander, let me add just one bit to the replies and counter responses. It IS NOT correct Internet behaviour to post full name, address, etc etc. Predators are everywhere. Student's should not use their real name (first name is OK) but a...

18 years ago

Its been a long time since I did this but I believe you pick the longest chain. If there are double and triple bonds involved, pick the longest chain that contains the double bond plus single bonds to go with it (but that is for alkenes isn't it?) When na...

18 years ago

762 + vp ethanol = total pressure. Dalton's Law of partial pressures. The total pressure in a flask containing air and ethanol at 257C is 882 mm Hg. If the pressure of the air in the flask is 762 mm Hg, the vapor pressure of ethanol is ?mm Hg.

18 years ago

delta T = ik_fm delta T is the amount f.p. is lowered. i is the number of particles; i.e., Na₃PO₄ will have i = 4 (3 for Na and 1 for PO₄). m is molality. k is a constant and need not enter into the calculations....

18 years ago

Let's do 1 and 2 and go from there. I will get you started. Take a 100 g sample. That means we have 19.9% C = 19.9 g C 46.7% N = 46.7 g N 6.67% H = 6.67 g H 26.7% O = 26.7 g O Find mols of these amounts. mols C = 19.9/12 = 1.66 mols N = 46.7/14 = 3.33 mol...

18 years ago

Opinions are ok but anything with identifying information will be removed. In fact, why don't you retype your question and omit the part about including name, address, et al. and we can get someone to remove your original post. ok.thanks,do you think you...

18 years ago

Kw = KaKb. With this equation you can convert any Ka to Kb and the reverse. Codeine (Cod), a powerful and addictive painkiller, is a weak base. a) Write a reaction to show its basic nature in water. Represent the codeine molecule with Cod. b) The Ka for i...

18 years ago

distance = rate x time or d = r*t car traveling 40 mi/hr goes 40 mi/hr x 1.5 hrs head start or 60 miles head start. Let t = time bus and car travel. car travels distance of r*t = 40*t. Car already had 60 mi head start. Total distance car traveled is 60 +...

18 years ago

Sorry, but I made two errors. Monocalcium phosphate is monocalcium monohydrogen phosphate which is CaHPO4. The Ca is +2, H is +1, and PO4 is -3 so the +3 and -3 balance. And Bob Pursley did NOT suggest that name of monocalcium dihydrogen phosphate, he was...

17 years ago

solution is made by mixing 20.0 mL of toluene C6H5CH3d=0.867gmL with 150.0 mL of benzene C6H6d=0.874gmL. Assuming that the volumes add upon mixing, what are the molarity (M) and molality (m) of the toluene For Further Reading * chemistry - DrBob222, Thurs...

17 years ago

Does anyone know details about quicken investment reports? My investment report suddenly won't work.

16 years ago

Posting the exact question more than once is superfluous and doesn't get an answer any faster. Miranda and another screen name did this yesterday. Perhaps you did all of them. At any rate, just post once please.

16 years ago

I have removed your extraneous answers from the last four or five posts. Please do not respond if you don't know the answer. If you persist in responding with rubbish you will be banned from this site.

12 years ago

I have a question my brother asked me but I need a math expert. You have two interlocking circles and the radius of circle B goes through the center of circle A and of course the radius of circle A goes through the center of circle B. The radius of each c...

12 years ago

I think you transposed the numbers for mass proton on your post yesterday which may be the reason you had trouble getting the answer in the book. I've posted a response at the original post which can be found here. http://www.jiskha.com/display.cgi?id=139...

11 years ago

Where are you getting all of this stuff? What university/college? Where do the exercises(questions) come from? What sources to you have for study? What percentage are you getting from Jiskha? Thanks. I'm just curious.

10 years ago

Since you are a biochemist please look at the post below by C. I tried answering the question but I really don't understand the question. Perhaps you can help.

10 years ago

I posted a response to your last two queries and now I can't find your original question nor my answers. Did you get everything taken care of on that H2S problem? My final answer was x = 0.00167 but also talked about how to solve the cubic equation using...

10 years ago

I posted a response to your Ksp/K but I was late doing it. Hope you saw it.

8 years ago

I see in the news reports that when the lava hits the ocean there is a spray of HYDROCHLORIC ACID. I don't see any way HCl can be formed. Acid, yes. H2SO3 yes. But not HCl. Any comments? Thanks.

7 years ago

What were prevailing styles of Gothic architecture? Select all that apply. ◻Gothic architecture followed classical Egyptian design. ◻Gothic architecture used flying buttresses to support outer walls. ◻Gothic architecture used rounded arches and Roman-styl...

5 years ago

Just a quick question to test your skills. What happens if you mix oxygen and nitrogen

4 years ago

How do I type Greek symbols on Jiskha with a normal keyboard? I see the &pi or &Delta or &lambda but that alone or in conjunction with <&pi> or <&lamda> etc doesn't get it.

4 years ago

I don't think so. Post your work and I'll look for the error.

14 years ago

Katrina- Please go to the to of the page, click on Post a New Question, and post your question. You will get better service that way.

17 years ago

<b>I think you have understood fairly well. My comments follow each of your responses.</b> HCl I know it is soluble because it is a strong acid, so it would be H+ and Cl^-. <b>Correct, and since this is a strong acid; i.e., 100% ionized, then there is no...

17 years ago

I don't see anything wrong with your answers; however, I think it is a poor question. For example, in question (a), why not include Na2S since that is soluble along with CuCl2 and KCl. All three are quite soluble so I would say that was to a marked degree...

17 years ago

I wouldn't call AgCl a solid solution. It is a salt that is not soluble in water except to a very limited extent (The solubility product is Ksp = about 10^-10). Salts may be soluble or not depending upon the solubility rules and you seem to have those rul...

17 years ago

Hydrogen bonding of the alcohol.

12 years ago

Ethene is C2H4 and not C2H2. Sorry about that. C2H2 is acetylene.

12 years ago

3Ca(NO3)2 + 2Rb3PO4 ==> Ca3(PO4)2 + 6RbNO3 mols Ca(NO3) = about 12.096/164.09 = about 0.0737. It's a factor. Notice how the units you don't want cancel and the unit you want to convert to remains. 0.0737 mols Ca(NO3)2 x [1 mol Ca3(PO4)3/3 mols Ca(NO3)2] =...

12 years ago

mols Ca(NO3)2 = grams/molar mass. molality = mols Ca(NO3)2/kg solvent delta T = i*Kf*m i = 3 for Ca(NO3)2 Then 0C-delta T = freezing point.

12 years ago

Ethene is C2H2. %hydrogen in C2H2 is (Mass H/molar mass)*100 = ? Then 150 x (%H/100) = ?

12 years ago

I beg to differ but you did not do that. If you had you would have the answer now. mols = 50.8E-3g/180.2 = about 0.0003 but you need to do it more accurately. Then 0.0003 mols/0.200L = about 0.0014 Then pi = MRT

12 years ago

See if this helps. It's almost the same thing. If you run into trouble let me know what the problem is and I can hel you through it. http://www.jiskha.com/display.cgi?id=1358879626

12 years ago

See your other post below.

12 years ago

Technically this can't be worked because the normality (and the equivalent weight) depends upon the reaction and the reaction has not been cited. However, usually this means H2SO4 will be 1/2 the molar mass for the equivalent weight. equivalents = mass/eq...

12 years ago

See above.

12 years ago

12M HCl means 12 mols HCl/L solution. Use density to convert L solution to grams. That is approximately 1200 grams (water + HCl). You know how much the HCl weighs; it is 12 mols or 12*36.5 = about 440g. Therefore, the water must have a mass of 1200-440 =...

12 years ago

See you post above.

12 years ago

This is a limiting reagent problem. I know that because amounts for BOTH reactants are given. Write and balance the equation. Convert Ca(NO3)2 to mols. mols = grams/m molar mass. Do the same for Rb3PO4. Using the coefficients in the balanced equation,conv...

12 years ago

It looks ok to me.

17 years ago

We can't draw structures on this forum. However, I don't know what Al2 + O2 is.

12 years ago

mols KOH = grams KOH/molar mass KOH. M KOH = mols/L soln.

12 years ago

Convert 15 oz to grams. I get about 425 but you should confirm that. Convert 761F and 34F to celsius. (mass ice x heat fusion) + [mass melted ice x specific heat H2O x (Tfinal-Tinitial)] + [mass warm water x specific heat warm water x (Tfinal-Tinitial)] =...

12 years ago

Multiply eqn 1 by 2. Add the reverse of eqn 2. This give you twice the equation you want so divide everything by 2. For dH. dH 1 + (-dH 2) = 2*dH total and divide by 2.

12 years ago

I thought I did this earlier.

12 years ago

A. If A = 2,500(MnO4^-) and you want A to be 1.00, Substitute 1.00 into the above and solve for (MnO4^-). B. Substitute 0.01 for A and solve for (MnO4^-) I don't get c.

12 years ago

1530 = Ccal*delta T 1530 = Ccal*(21.85-20.5) Ccal = ? q = Ccal*delta T salt. q = Ccal from above x (delta T)

12 years ago

Do you mean calcium sulfite (CaSO3) or calcium sulfate(CaSO4)? Your question states calcium sulfate but you have written calcium sulfite for the formula. I suspect that is a typo and you intend for it to be CaSO4.

17 years ago

Assuming you made a typo and it is CaSO4, calcium sulfate. Convert 6.60 x 10^6 kg to S. 6.60 x 10^6 kg coal x 0.016 = ?? kg S. There is 1 mol S in 1 mol SO2 and it requires 1 mol CaO to react with it. Therefore, you need not go through all of the intermed...

17 years ago

<b>I have added some comments to all of them but you need to go through and expound on what I have written.</b> why would the mixture between 0.1 M acetic acid (conductivity of 7) and 0.1 M ammonia (conductivity of 8) result in a conductivity of 8? <b>Bot...

17 years ago

...........I2 ==> 2I equil mols I = 0.0356g/about 127 = about 2.8E-4. M = mols/L = about 2.8E-5. You need to confirm these numbers. Kc = (I)^2/(I2) You know equil (I) and Kc, calculate (I2).

12 years ago

Be sure and check (confirm) those numbers. I just ran them one time on my calculator.

12 years ago

mols H2 @ equil = 0.627g/2 = 0.3135 M H2 @ equil = 0.3135/2L = 0.1567M M H2 begin = (1.441/4) = 0.360M M Br2 begin = (70.24/159.8) = 0.440M ........H2 + Br2 ==> 2HBr I.....0.36..0.44.....0 C.....-x.....-x.......2x E...0.36-x..0.44-x...2x At equil (H2) = 0...

12 years ago

Since you want density unit in g/cc, I would adjust the starting units, like so. 7.0 x 10^5 km = 1.0 x 10^10 cm (It's easier to do this at the start than at the end for me.) The volume of a sphere is (4/3)*pi*r³ = ?? cc Then mass = volume x den...

15 years ago

Looks like a secondary amine to me.

12 years ago

2C57H110O6 + 163O2 ==> 114CO2 + 110H2O

12 years ago

You may have one(1) atom of an element or many atoms of an element.

12 years ago

You can correct the wet hydrogen to dry hydrogen at SATP by using p1v1/t1 = p2v2/t2 p1 = 101.62 kPa - vapor pressure H2O at 23 C. This gives the pressure of H2 alone. You can find the vapor pressure in tables. My table gives 21.1 mm Hg so you will need to...

12 years ago

mols = grams/molar mass.Solve for mols. M = mols/L. Solve for M. pi = MRT. Solve for pi = osmotic pressure.

12 years ago

Add 2.86 + 0.09 and calculate volume. Subtract 2.86 - 0.09 and calculate voluem. The uncertainty is the difference in the two volumes.

18 years ago

|4x-6|=26. We don't know if x is + or - so we work it both ways. If x>0, then 4x-6=26 4x=32 x = 8. If x<0, then -4x+6=26 -4x=26-6=20 4x = -20 x = -5 That is |x| = -x when x<0.

18 years ago

The number can be raised to a fractional power. For example, sqrt 2 = 2^1/2 4th root 3 = 3^1/4

18 years ago

which events. You need to tell us what is going on or we can't help. What you have posted is not a stand-alone question.

18 years ago

mass = volume x density volume = mass/density volume of flask = 26.33/0.9970 = 26.41 cc or therebouts, not 37.45. I didn't go through the remainder except that the mass of liquid is correct at 14.67. Repost if this doesn't clear it up for you.

18 years ago

<b>water mass = (78.19g + 23.94g)-37.34g= 67.79g Vol of water = Mass/Density 67.79g/(0.9970g/cm^3)= 67.99cm^3 </b> I'm not sure I buy this part. mass flask + metal + H2O = 78.19 mass flask + metal = 61.28 mass H2O = 78.19-61.28=16.91 g OR flask + metal +...

18 years ago

You are getting confused with the numbers. Go back to square 1. You were correct before that mass H2O = 26.33 g. mass liquid = 14.67 g. volume of H2O = 26.33/0.9970 = 26.409 cc = volume of the liquid. so density of liquid = mass/volume =14.67/26.409 = 0.5...

18 years ago

Mass of empty flask plus stopper: 37.34g mass of stoppered flask plus water: 63.67g Mass of stoppered flask plus liquid: 52.01g Mass of water: 63.67 - 37.34= 26.33 Volume of Flask(density of H20 at 25*C, 0.9970 g/cm^3: <b>You are ok to here.</b> (37.34g)/...

18 years ago

This is a fairly standard procedure which you should be able to look up in your text. Basically, you weigh the Na2CO3 and titrate with the HCl to the methyl red or methyl orange end point. I have omitted drying the primary standard, boiling the solution a...

18 years ago

x = number product of 1000*743 so x = cube root(1000*743) or another way is x = (1000*743)^1/3

18 years ago

Write the equation. HCl + NaOH ==> NaCl + H2O mols NaOH = M*L = 0.10 M x 0.1 L = ?? mols HCl = M*L = 0.15 M x 0.075 L = ?? See which is in excess, how much is left over after reacting, then pH = - log(H^+). Post your work if you get stuck.

18 years ago

No. Since the product is NaCl and water and the NaCl doesn't hydrolyze, the H+ or OH- comes from the excess of HCl OR NaOH. Look at the mols HCl and the mols NaOH. Calculate each according to my last post. You will see one is larger than the other. So sub...

18 years ago

A note that when you subtract the difference is the MOLS of excess reagent. The concentration is mols/L to calculate H+ or OH- so mols/0.175 L is the concentration.

18 years ago

5*101 = 505 10*101 = 1010 20*101 = 2020 50*101 = 5050 That statement looks good to me although you may want to work on the wording a little. The product ends in 5, 10, 20, and 50 respectively and those are the numbers by which 101 were multiplied. How abo...

18 years ago

http://en.wikipedia.org/wiki/Conjecture

18 years ago

I would change each mixed fraction as follows to a fraction: 5 7/16 = (5*16)+7 = 87/16 4 1/19 = (4*19)+1 = 77/19 9 3/17 = (9*17)+3 = 156/17 Then find the lowest common decnominator and go from there.

18 years ago

When all else fails, you can always use 16*17*19. That may not be the lowest but it will always work. The final answers may be reducible.

18 years ago

I get 496 also.

18 years ago

I had lab when I tok chemistry in high school and think that was standard practice. However, more modern times have arrived and there are many schools that teach AP chemistry without labs. I suppose they save money that way. I am not in favor of that but...

18 years ago

First of all, I think freshman chemistry class without a lab deprives the student of what chemistry is all about. I learned as much from the labs as I did from lectures and in some cases I learned more. I will go further than Bob Pursley and say I'm not a...

18 years ago

That test I couldn't remember for entrance to medical school is the MCAT test. That is the biggee for med school now, and has been for a number of years. And the GRE has become about the same for grad school. In Louisiana now, we have promotional tests, o...

18 years ago

It depends upon how you define cheaper. IF you mean the cheaper to purchase, obviously $18 is cheaper than $40.80. On the other hand, 40.80/250 = 0.163 per item while the other one costs 18/100 = 0.18 per item. So on a per item basis, the cheaper is the o...

18 years ago

Let x be the variable, then 8-x and 2*x

18 years ago

₁₇Cl is 1s2 2s2 2p6 3s2 3p5 so what does Cl need to complete its octet?

18 years ago

yes. Although I wouldn't go so far as to say the chlorine ACCEPTS an electron from the carbon. I would prefer to say that one electron from the Cl and 1 from the C were shared to form a C:Cl covalent bond. The bond will be somewhat polar because of the di...

18 years ago

Add like terms. For example, on the left 5X + 22X - 38X = -11X on the right -17 -9 + 12 = -14 -11X-9-19 = 17X-14 Combine the -9 and -19 -11X-28=17X-14 Now add 28 to both sides -11X-28+28 = 17X-14+28 -11X=17X+14 Subtract 17X from both sides -11X-17X=17X-17...

18 years ago

Yes, 0.6 page per one hour does make sense. You could also have a unit rate if we did it the other way. 5/3 would be 1.67 hours per one page. From the question I can't tell which one you prefer but I think either would be ok since both are unit rates. One...

18 years ago

2*3^3+4 grouped as 2*(3³⁺⁴) = 2*(3⁷) = 2*2187 = 4374. Ta-dah!!

18 years ago

F = [C*(9/5)]+32

18 years ago

Just a small typo in the last post. Instead of <b> F + (9/5)C + 32 </b> Change <i> F + (9/5)C + 32 to F = (9/5)C + 32.</i>

18 years ago

Use the pipe symbol for the absolute marks. |2-1| = |1| = 1 A different problem follows: |-2+1| = |-1| = 1

18 years ago

(72x)^3/2

18 years ago

See answer above.

18 years ago

Yes. sqrt 7² = 7 because 7^2/2 = 7¹ = 7

18 years ago

heat lost by lead + heat gained by water = 0 masslead*specific heat lead * (Tf - Ti) + mass H2O * specific heat water * (Tf - Ti) = 0 Tf is final T Ti is initial T. solve for Tf. Post your work if you get stuck.

18 years ago

Yes, we can help. You posted this earlier and Bob Pursley told you that 176 g sounded high to him and for you to show your work and we would find the error. So show your work how you obtained the 176.24 g theoretical yield.

18 years ago

First, that's not how to determine the theoretical yield. Second, Cu is 63.5 something and not 12.01. You have used the atomic mass of C and not Cu.

18 years ago

No, of course not. You just calculated that you have 0.0626 mol CuSO4 and 1.76 mols NH3. Let's review what you and Christina have done. Convert 10.0 g CuSO4 to mols. mols CuSO4 = 10/159.6 = 0.0626 CuSO4, Convert 30.0 g NH3 to mols. mols NH3 = 30/17 = 1.76...

18 years ago

Yes, you are correct. I didn't convert 0.250 mols NH3 to grams and I should have done so. That's what I get for not looking at the problem I was trying to do it from memory and I forgot a step. So 0.250 mol NH3 x 17 g/mol = 4.25 and 30-4.25 = g NH3 remain...

18 years ago

So what is to be done?

18 years ago

If the equation is: (3x/4) - (2x/5) + (x/2) Common denominator is 20 (15x/20) - (8x/20) + (10x/20) = combine the three to obtain 17x/20

18 years ago

72/-24 = -3 a^2/a^2 = 1 b^3/b^5 = 1/b^2 so = -3/b^2

18 years ago

What is a variable? It might be x or y or b or w. A one variable equation has one of those; a two variable equation has two of them. 2X + 14 = cost of ham. 1 variable. 2X+3Y = coat of ham. 2 variables.

18 years ago

Job 1 use Roel because it takes only 1 hr for the job to be done. All others take longer. Job 2 use Noel because it takes only 2 hrs for the job to be done. All others take longer. We have Noel and Zoel left. Job 3 takes Joel and Zoel the same length of t...

18 years ago

Just expand the binomial. You know how to do it? First term is (2y)^2 = 4y^2. Second term is twice the product inside the parentheses which is 2y*-3 = -6y and twice that is -12y. The third term is the last number squared which is -3² or +9. Do...

18 years ago

A point of clarification: A is not the correct answer.

18 years ago

duplicate post

18 years ago

Substitute 2x+1 into equation 1 for y and solvee for x.

18 years ago

For CO2 vs CO, look at the structure. CO is a linear molecule (it must be because that is the only way to put two atoms together). Since the electronegativity of C is about 2.4 and that of O is about 3.5, the CO molecule is a dipole (it is a polar bond) b...

18 years ago

I don't believe so. (p^x)^y = p^xy. Try it. (3²)³ = (9³ = 729 OR 3⁶ = 729 The rule as written is correct but that isn't the problem. )

18 years ago

If the equation is x-[3*(2x+1)]=8, then multiply 3 times what is inside the parentheses. x-[6x+3]=8 now remove the parentheses (in this case the brackets). x-6x-3=8 combine x terms. -5x-3=8 move the 3 to the other side(change the sign when you do so). -5x...

18 years ago

We found different answers because I added parentheses to distinguish between two possible scenarios.

18 years ago

duplicate post

18 years ago

Boiling points depend more upon the INTERmolecular forces than they do on INTRAmolecular forces. Boiling points depend upon both the forces between molecules AND the molar mass of the compound. You are correct that the CH3Cl bond should be stronger than t...

18 years ago

1. Is the Cl2 given in the problem as one of the products or is that what you think? I don't believe Cl2 is produced. NaCl + H2SO4 + NH3 ==> Na2SO4 + NH4Cl. You need to balance it. You may see this reaction better if we write it in two steps. NaCl + H2SO4...

18 years ago

Convert 0.1964 g TlI to mols TlI. Convert mols TlI to mols Tl2SO4. Convert mols Tl2SO4 to grams Tl2SO4. Convert grams Tl2SO4 to percent of 10.20 g sample. Post your work if you get stuck.

18 years ago

I posted a correction at the original site. Yes, you are correct. I didn't convert mols NH3 to grams and I subtracted grams - mols which isn't legal. But I think the remaining part of the problem is correct. That's what I get for trying to do the problem...

18 years ago

Right on!

18 years ago

http://www.mslawyer.com/statutes/landlord.html http://www.federalrealestate.net/laws/ms.html

18 years ago

It works, too. Thanks, Leo.

18 years ago

It may be true that anyone can post there but that is true for almost anywhere on the web. One NEVER knows whether the information is good or bad. That said, Wikipedia contains some very valuable information. The thing to do is to read several of the arti...

18 years ago

(1 2/5)/21 = (7/5)/21 = (7/5)x(1/21) = 1/15.

18 years ago