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Posts by DrBob222

Total # Posts: 54,989

math
Now it all makes sense.

hookle's law
John, are you sure about this?

Chemistry
No and yes. Ptotal = pH2 + pH2O. pH2 is given as 742.5 I assume you looked up the vapor pressure of H2O at 20 C and found 17.5 torr. So 742.5 + 17.5 = 760. I think you just made a typo and hit = instead of +.

@Kylee--chemistry
See your post above. Al is limiting but your calculation is faulty. Damon worked the problem for you correctly.

chemistry
Is that 7,366.3257 in what units? Torr? Do you want to convert that to Pascals or atmospheres? How many significant figures do you want? By the way, most internet forums, such as this one, do not treat subscripts and superscripts very well but the way you're doing it is ...

chemistry
No. When you say to round you must also say to how many places. If you want it rounded to 3 places AND in exponential form, it is 7.37E3

Chemistry
OK. You have a benzene ring. If it has only one attachment, it is C6H5 then you add the attachment. If it has the OH AND COOH attached to the right it is C6H4(Cl)COOH, etc. For example, C6H5COOH is benzoic acid.

Chemistry
Try writing the formula out as a line formula;i.e., ClCH2CH3COOH

Chemistry PLEASE HELP ME
a. What's wrong with a thermos for this. b. What about a closed box? c. Encapsulate in plastic. How about that?

Science (soon if so)
I don't agree with #2. Nanotechnology doesn't create new atoms.

Chemistry
See your post above.

Science
Technically, one can't calculate this BECAUSE there is no reaction given; however, we usually assume, when the reaction isn't given, to use total + or - charge. That is 2 in this case; therefore, mL x N x mew = grams where mew is milliequivalent weight. equivalent ...

chemistry
You really need to find the caps key on your keyboard and use it. L is liters, not l, Hg is mercury, not hg, and sentences start with a cap letter. Use P1V1 = P2V2 Post your work if you get stuck.

Science
I looked at this earlier. My problem with this problem is that I don't believe the first equilibrium can be right; therefore, I just decided to leave it.

Chemistry
Yes, mols CO2 is same as mols O2. I see it this way. Start with 10 dm3 O2 so end with 10 dm3 CO2. d O2 to start = 32/22.4 = about 1.42 g/dm3 if at STP. At 300 K it will be 1.42 x 273/300 = ? CO2 at STP will be 44/22.4 = about 1.96 g/dm3 at STP or 1.96 x 273/300 = ? Then ...

Science
And you want someone here to write a paper for you? No thank you. The best help I can give you is to suggest you go to Google and search on "analytical chemistry" or "how to develop and use new skills in analyzing a new medicine". Good luck.

Chemistry
You must know the solubility rules for this. a. NaOH added gives you Co(OH)2 and Al(OH)3. Both hydroxides are insoluble so they can't be separated that way. b. Neither Ba(NO3)2 nor KCl form a ppt, both will be soluble and they can't be separated that way. c. Both Mg(OH...

Verbal reasoning
right. But the concept is to put something down on paper so you cn see what is happening.

Verbal reasoning
I don't do this my verbal but I must draw a picture. Tom is taller than Mary so ........Tom ........Mary Then Mary is taller than Ann so Ann must go below Mary like this. ........Tom ........Mary ........Ann So who is the shortest?

Chemistry
I just did one for you. What don't you understand about balancing equations? We need to help so you can do these yourself.

Chemistry
As far as I know there is no lead(III) nitrate.There is a lead(II) nitrate. 2Pb(NO3)2 ==> 2PbO + O2 + 4NO2

Chemistry
See your questions above.

Chemistry
See your other questions.

Chemistry
Let's make this a little simpler. Why not call a1 just a. Then 4a + 3O2 ==> 2A2O3. On second thought, I'll bet that is Al (for aluminum so that's an ell and not a number 1) so 4Al + 3O2 ==> 2Al2O3. What I do for limiting regent(LR) problems is to convert Al ...

Chemistry
It goes with whatever anion you added to the [Cu(H2O)6]^2+ (i.e., chloride, bromide, sulfate, etc.

chemistry
You need to learn how to use the caps key. That's K2CrO4. All compounds must add to zero with oxidation numbers. K + +1 O = -2 (2*+1) + (Cr) + 4(-2) = 0 2+Cr-8 = 0 Cr-6 = 0 Cr = 6

Chemistry
https://onlineconversion.vbulletin.net/forum/main-forums/convert-and-calculate/8860-kg-m2-to-kpa

Chemistry
I would rather show you how to do it. mols CO2 = grams CO2/molar mass CO2 = ? Then there are 2 mols O atoms for every mols CO2 Then there are 6.02E23 O atoms in a mols of O atoms. Unless I punched in the wrong numbers on my calculator, the correct answer isn't there.

Chemistry
I can help you best if you tell me the trouble you are having doing this.

Chemistry
1 Ca = 1 CaO = 1 C2O4^2- 2MnO4^- + 5C2O4^2 ==> .....- mew = milliequivalent weight. mL x N x mew = grams Then (grams/mass sample)*100 = ? mL = 40.0 N = 0.250 mew = 1/2(molar mass CaO) I get answer of 52.1%. The molar mass CaO may be a little different in your text/notes. ...

chemistryt
This is a common ion problem. .....PbI2 ==> Pb^2+ + 2I^- I....solid....0.......0 C....solid....x.......2x E....solid....x.......2 Ksp = (Pb^2+)(I^-)^2 Ksp = ? (I^-_ is 2.7 M. (Pb^2+) = 1/2 (I^-) Substitute and solve for Ksp.

chemistry
Note the correct name is ammonium chloride. It is acid because the ammonium ion (the NH4^+) is hydrolyzed as follows: NH4^+ + H2O ==> H3O^+ + NH3 The hydronium ion makes it acidic.

Chemistry
Some work better in acid medium, some work better in alkaline medium and some, permanganate for example work differently in acid and base. MnO4^- is reduced to Mn^2+ in acid medium but to MnO2 in basic medium.

College Chemistry
It's a mole fraction problem and it's very similar to a fraction problem in math. In math, for example, if you have 4 apples and 6 oranges, the fraction of apples is 4/10 (number apples over total fruit) and the fraction of oranges is 6/10. In mols it's the same ...

Chemistry
You're on the right path. M = mols/L so mols = M x L You know M and L, calculate mols KNO3. Since there is 1 mol nitrate ion in 1 mol KNO3, then mols NO3^- = mols KNO3.

Science, Chemistry
I can do all of this for you but tell me what your main problem is. Surely these are in your text, on the internet, or in your notes. Or, perhaps you have them done and you just want to check your work.

Chemistry
mols Mg(NO3)2 = grams/molar mass = ? Then you know that 1 mol Mg(NO3)2 contains 6 mols O atoms.

Chemistry
1 mol contains Avogadro's number. So use PV = nRT and calculate which is 1 mol.

Science
a. Power in watt hrs = volts x ampere hours b. coulombs = amperes x seconds c. See b above. d.e. This should get you started. You can google this stuff.

Chemistry
You're stuck with the math. You clear the parentheses first. 1800 = 40*0.903*Tf - 40*0.903*25 Now combine terms, then Solve for Tf, the only unknown in the equation. That's the final T.

Chemistry
q = mc(Tfinal-Tinitial) 1800 =40*0.903(Tf=25)

Chemistry
mols = grams/atomic mass = ? Water is H2O but I don't know what you mean by a "method".

Chemistry
No. Schaum's is right. If I do it I get 55.3587 mL which rounds to 55.4 mL. You must be punching in the wrong numbers or the wrong key somewhere. Make sure you haven't transposed a number.

Chemistry
me = milliequivalents. me IO3 = me NH2NH2 and me = mL x N, then mL x N = mL x N Substitute and solve for mL IO3

Chemistry
Call the organic acid Hox. Then the barium salt will be Ba(ox)2 and since it is a dihydate it will be Ba(ox)2*2H2O. Ba(ox)2*2H2O + H2SO4 ==> BaSO4 + 2Hox + 2H2O. mols H2SO4 = M x L = ? Convert to mols Ba(ox)2*2H2O. That is 1:1 so you have mols Ba(0x)2*2H2O = mols H2SO4. ...

Chem
dT = i*Kf*m i = 2.34/1.86*0.649 i = 1.938 so it's not quite 2.0 which means it's 93.8% ionized. ........HA ==> H^+ + A^- I....0.649.....0.....0 C......-x......x.....x E....0.649-x...x.....x You know x = 0.938*0.649 = 0.609 = (H^+). Plug those numbers into Ka ...

chemistry
What is your problem with this? I'll be glad to help you through it.

chemistry
Do you know the properties of a base and acid. What's wrong with litmus paper?

Chemistry
First, your post is confusing. I found the following equation on the net and I assume the 150 mg Zn is in the form of the ion and not solid. If all of that is true, then 3Zn(NO3)2 + 2K4[Fe(CN)6] ? K2Zn3[Fe(CN)6]2 + 6KNO3 Then mols Zn = grams/atomic mass = ? Convert mols Zn to ...

Consider the following equation: CO + 2 H 2 → CH 3
What about it?

chemiste-ry
You have 128 kJ heat released with 4*1.01 g hydrogen or 4.04 g hydrogen. So how much would be released with twice the amount of hydrogen?

Chemistry
mols = grams/gfm You say you have mols and you know grams, solve for gfm.

chemistry
The easy way is to place a drop of phenolphthalein in it. It will turn pink. The equation isn't easy to write. Another way, with an equation easier to write is to treat the NaOH with NH4Cl. NH4Cl + NaOH ==> NH3 + NaCl + H2O The odor of NH3 is not easily mistaken.

@ Abby---Chemistry
Abby, you need either the molarity of the HCl or some way to calculate the molarity. The density will do it or the molarity will do it; otherwise, it can't be done. Expecting to convert mL to mols without knowing how strong the solution is is like asking how many apples ...

@vikki---Chemistry
I want to point out to you that you need to find the caps key on your keyboard and use it. You may (or may not) know that m stand for molality and M stands for molarity. Two separate animals. My assumption is that you meant M = molarrity and MathMate worked it that way, also. ...

science
A beaker to hold the stuff?

Chemistry
1. Write and balance the equation. You have that. 2. mols CH4 = grams/molar mass = ? 3. Using the coefficients in the balanced equation, convert mols methane to mols H2. For every mols CH4 you will need 2 mols H2. 4. Now convert mols H2 to grams H2. grams H2 = mols H2 x molar ...

Science
1. They are in the same group in the periodic table. 2. They have similar chemical properties. 3. All three are metals. 4. They have one electron in the outside shell. and more.

chemistry
Mostly as a moisturizer (emollient)

Chemistry
Not enough of it AND the convection currents don't allow the CO2 to immerse the flame.

Chemistry
In one second it is 2E8 cm x 0.01 = ? and convert that answer in cm to meters.

Math
On second thought, I guess it really IS math. I see mathmate plugged in 20 for t but that isn't clear to me in the problem.

This is math?...Math
I don't get this. What is that half life function supposed to calculate. You have two unknowns; i.e., t and Ao AND is Ao the percent? Can't be. Is B a separate problem? Just look up the half life and plug into ln(No/N) = kt.

Chemistry
I always assume that if T is not given that we assume Kw = 1E-14. Yes, you know (H^+) = 1E-4 and since ka2 is so much smaller than ka1 you ignore the H^+ from ka2. And you're right that H2X dissociats to H^+ and HX^- but you're incorrect after that. Let Y = (H2X...

Chemistry
That's right. M = mols/L or mols = M x L = ? Four steps. 1. Write and balance the equation. Ba(OH)2 + H2SO4 ==> BaSO4 + 2H2O 2. Convert what you have to mols. mols Ba(OH)2 = M x L = ? 3. Using the coefficients in the balanced equation, convert mols Ba(OH)2 to mols ...

Science
Stronger

the fed
I thought the IRS collected income taxes, not the federal reserve.

Chemistry-pH
Sorry I goofed but all the numbers stay the same. I should have used NaOH and not KOH but both are strong bases and neither Na ion nor K ion are involved. Both are spectator ions anyway. Usually I don't use the cations anyway and write HX + OH^- ==> X^- + H2O or X^- + H...

Chemistry-pH
Yes, KOH is used up. Since the volume added is the same we can keep the molarity. .....HX + KOH ==> KX + H2O I....0.2...0.1.....0....0 C...-0.1..-0.1...+0.1....0 E....0.1....0......0.1..0.1 pH = pKa + log base/acid 5.3 = pKa + log 0.1/0.1 so pKa = 5.3 For part 2 to change ...

Chemistry
....CrPO4 ==> Cr^3+ + PO4^3- I...solid.....0........0 C...solid.....x........x E...solid.....x........x Substitute the E line into Ksp expression for CrPO4 and solve for x = solubility.

chemistry
I don't see that you've done anything yet. The question is about your car, not mine. How much does the tank hold? How much do you drive in a year. How many miles do you put on. What is the gas mileage. Write and balance the equation. Then you use stoichiometry. Do you ...

chemistry
This is two unknowns so it requires two equations and solve them simultaneously. First, you must determine the grams NaBr and grams KBr. Let X = grams NaBr and Y = grams KBr ==================== equation 1 is X + Y = 0.981 equation 2 is obtained by converting grams X to grams ...

Thermochemistry
Right. I did this for you yesterday.

Science
The solubility is 36 g/100. So what's the solubility in 50 g? That's 36 g salt x (50/100) = 18 g. You have 15 g to put in the 50 g H2O. So will that be saturated or not?

Health and PE (alcohol)
No, my specialty is chemistry and not H and PE but for what it's worth, here are my thoughts. BTW, I would expect you could find the answer in your text/reading material. The skills you need to say no to alcohol are called what? Unsure You need discipline. You need "...

Jiskha
Bob Pursley is a tutor. The webmaster is Leo. All of the tutors here are unpaid volunteers. Most are retired teachers/administrators but some are retired professionals.

Chemistry
mols sugar = grams/molar mass = ? mols H2O = grams/molar mass = ? XH2O = mols H2O/total mols = ? pH2O = XH2O*PoH2O Post your work if you get stuck.

Chemistry
1. Write and balance the equation. 2. Convert g to mols for each reactant. mols = grams/molar mass = ? 3. Using the coefficients in the balanced equation, convert mols each reactant to mols product. You will likely obtain two different values for mols of the product. The ...

Thermochemistry
heat lost by Sn + heat gained by H2O = 0 [mass Sn x specific heat Sn x (Tfinal-Tinitial)] + [mass H2O x specific heat H2O x (Tfinal-Tinitial)] = 0 Substitute and solve for mass Sn. Post your work if you get stuck.

Chemistry-kd
I think you are talking about two different applications. The formula not taught in your school is for the purpose of calculating Kd ONLY (or if one knows Kd, it will give you the fraction of solute remaining in the aqueous phase after n extractions). It allows you to go ...

Chemistry-kd
Not to worry. Yes, it is a general equation. If you were to do 4 extractions you would need to go through the Kc = [(mg x org layer/volume)/(mg x aq layer/volume)] four times. After the first time you would take the amount in the aq layer, extract that a second time, take what...

Chemistry-kD
I assume when you say 10 mg remained that it was 10 mg in the aqueous layer. 1. f = [1+ (Kd*Vo/Va)]^-n f is the fraction X recovered. Kd is distribution coefficient with organic layer/aqueous layer usually written as Ko/a - Kc. Vo is volume of organic layer. Va is volume of ...

Chemistry
yes

Chemistry
You have the right idea but the wrong numbers. You have calculated mols Al. You want mols Al2O3; the problem asks for mols Al2O3.

Chemistry
I agree with 5.02 g Fe produced.

physical science
Actually, they don't. Most liquids have a u shape but liquid mercury has the reverse. If it is a U shape, the liquid adheres to the wall of the tube and that attractions is stronger than the attraction between molecules of the liquid in the middle part of the U.

Chemistry-titrations
I assume Hph stands for phenolphthalein, or if not, then it changes color in the same pH range as phenolphthalein which is approx 8.3 or so. Also, I assume that all of the (NH4)2CO3 reacts, all of the NH3 is boiled away, and an excess of NaOH remains with the Na2CO3. Your ...

chemistry
Is it more dense or more viscous.

Chemistry
If you follow up I suggest you post new at the top; otherwise, this will be so far down the list that it will be difficult to find.

Chemistry
From your last post, initial mols Ba(OH)2 = 0.4 x 50E-3 or if you want to use the 0.2, because the 50 cc was diluted to 100 cc, then mols Ba(OH)2 = 0.2 x 100E-3. Either way you have same mols which is why I like to use the initial mols Ba(OH)2 as 0.4*50E-3, work through the ...

Chemistry
You don't post easy questions. Thanks for sharing your thoughts. That helps. Here are my thoughts/questions. 1. The problem says make appropriate assumptions and calculate (HA) and Ka. I'm not sure what "appropriate" means so I went through the possibilities...

Chemistrt
Let's let lambda be L and drop the n1 and n2. Since n1 = then that squared is 1/4 and n2^2 will just be n^2 1/L = R(1/4 - 1/n^2) 1 = RL(0.25-1/n^2) 1 = RL[(0.25n^2-1)/n^2] n^2 = RL(0.25n^2-1) n^2 = 0.25RLn^2-RL n^2-0.25RLn^2 = RL n^2(1-0.25RL) = RL n^2 = [RL/(1-0.25RL)] ...

Chemistrt
If you have a problem with numbers, the easy thing to do is to leave the equation as is, substitute the numbers, the solve for the unknown in the equation. If you get stuck, post the numbers and someone can help you through.

Physical science CHECK my answers
5 is not right. The others look OK to me.

Chemistry
You didn't provide any data. You need to fill in the blanks.

Chemistry
Ethanol is polar and has hydrogen bonds.

Chemistry
mols = grams/molar mass so grams = mols x molar mass

Science
I don't know how useful this will be but here it is. http://k12.phys.virginia.edu/Labs/Lab05.pdf Also check out the directions, especially 2b 3. That should be a good starting point for an experiment. Good luck.

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

Chemistry
mols Ar = grams/molar mass = ? mols Ne = grams/molar mass = ? mols unk = grams/molar mass but you don't know the molar mass of this; therefore, you can't calculate this at this point. total mols = mols Ar + mols Ne + mols unk. Use PV = nRT to calculate total mols. Then...

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