Tuesday
September 16, 2014

Posts by DrBob222


Total # Posts: 43,812

Chemistry
Calculate the molarity of the concentrated HCl. You made a typo and omitted the % after 37. M HCl = 1000mL x 1.20g/mL x 0.37 x (1 mol/36.5g) = about 12.2M Then mL1 x M1 = mL2 x M2 mL1 x 12.2M = 2850 mL x 0.500 Solve for mL 1 you need. Take mL you've calculated, add to a ...
May 7, 2014

chemistry
mols = grams/molar mass
May 7, 2014

chemistry
I don't know and we can't find out. mols NaOH = M x L = approx 0.0042 IF the unknown acid is a monoprotic acid, then mols acid = mols base and mols acid = grams/molar mass You know mols acid and grams acid, calculate molar mass acid. However, the problem doesn't ...
May 7, 2014

chemistry
See your other post under Harley.
May 7, 2014

chemistry
See your other posts. Just one is all ou need to see how to do these.
May 7, 2014

(11) Chemistry - Science (Dr. Bob222)
I'm sticking my neck out but go through this reasoning and see if you agree. reactants --> products k = P/R For k to be < 1, reactants must be favored. Just try A; if dH is - the reaction would be R ==> P + heat If we increase T the reaction will be shifted to the...
May 7, 2014

Chemistry - Science (Dr. Bob222)
A. dG has nothing to do with speed of a reaction. Carbon is the more stable form of diamond but all the girls getting diamond rings today need not worry about that ring crumbling tomorrow. :-). B. All reactions occur to some extent no matter how small. So this has an extremely...
May 7, 2014

science
I know very little about biology but that's what I think.
May 7, 2014

science
https://answers.yahoo.com/question/index?qid=20110503190756AADMkC7
May 7, 2014

CHEMISTRY HELP !!!!
OK. I told you how to do it. Do you need more assistance or do you have the right answer now?
May 7, 2014

CHEMISTRY HELP !!!!
What does either B or E mean? To me it means you don't know and you're guessing because they aren't close to each other. How many coulombs did you use. That's amperes x seconds = coulombs. Then you know that 27/3 = 9 g Al will be deposited for every 96,485 ...
May 7, 2014

CHEMISTRY HELP !!!!
ok Now we can do something. Make the top numbers add up and the bottom numbers add up. on the left. top...1 + 235 = 236 bottom 0 + 92 = 92 which does nothing more than show that 236/92U is right. Now to the next part of the reaction. top: 236 = 137 + ? + (2*1) and solve for...
May 7, 2014

CHEMISTRY HELP !!!!
What's with the 1/2n? neutrons are 1/0n
May 7, 2014

CHEMISTRY HELP !!!!
Either you've made a typo or this is a screwed up question. 236/92 can't be Te. It MUST be U. And what is 2(1/2)n? neutrons are 1/0.
May 7, 2014

CHEMISTRY HELP !!!!
nope. And example for element X and I'll make up numbers. 24/12X ==>beta + Y 24/12 X ==> 0/-1 e + zYw and you want to know what z and w are. The upper numbers add up on both sides. The lower numbers add up on both sides. upper number first. 24 = 24 + ? so w must be 0...
May 7, 2014

Chemistry
22% w/w means 22 g solute Z in 100 g solution. mols in 22 g = 22/215.2 = ? Use density to convert 100 g to mL and convert to L. Then M = mols/L
May 7, 2014

Chemistry
mols K2SO4 = grams/molar mass Then M = mols/L solution.
May 7, 2014

Chemistry
The position of the metal and metal ion in the activity series.
May 7, 2014

chemistry
Probably none. Fe2O3 is not soluble. Sr3(PO4)2 is insoluble. No reaction.
May 7, 2014

chemistry
A. mols soln A = mol/dm3 x dm3 =? mols soln B = same thing. Bi. total mols HCl = mols of A + mols B Bii. NH3 + HCl ==> NH4Cl mols HCl you have. From the coefficients in the balanced equation, you know mols NH3 = mols HCl Then mols NH3 = mol/dm3 x dm3. You know mols and mol/...
May 7, 2014

chemistry
2Al(OH)3 + 3H2SO4 --> Al2(SO4)3 + 6H2O 1) How many mols Al(OH)3 do you want? That's M x L = 0.672 x 0.500 = approx 0.3 but you should be more accurate than that. mols Al(OH)3 = grams/molar mass. You know mols and molar mass; solve for grams. 2)How many mols H2SO4 did ...
May 7, 2014

chemistry pls help me asap
3NaOH + H3PO4 ==> Na3PO4 + 3H2O mols NaOH = grams/molar mass = 4.0/40 = 0.1 mol. a) M NaOH = mols/dm3 = 0.1mol/0.1 dm3 = 1M b) From the equation, 3 mol NaOH = 1 mol H3PO4; therefore, 40 cc (0.04 dm3) of NaOH x 1 M = 0.04 mols NaOH. mols H3PO4 = 1/3 of that or 0.04/3 = about...
May 7, 2014

chemistry
This is done by the same procedure as the NaOH/H3PO4 problem above.
May 7, 2014

chemistry
mols Al2(SO4)3 = M x dm3 = ? mols Al = twice that mols sulfate = thrice that
May 7, 2014

CHEMISTRY HELP !!!!
It's D isn't it? That's the equivalent of my response.
May 7, 2014

CHEMISTRY HELP !!!!
(CN)2(en)2Zr(IV)NO3 which I wrote just following your words. Then I would rearrange this to [Zr(en)2(CN)2](NO3)2 Check me out on this.
May 7, 2014

Chemistry
2C4H10(g)+13O2(g)→8CO2(g)+10H2O(l) mols butane = grams/molar mass Using the coefficients in the balanced equation, convert mols butane to mols CO2. Now use PV = nRT and solve for V in liters. n = number of mols calculated in step 2.
May 6, 2014

Chemistry
Here is how you do ionic equation but I've gone a step further to show how to obtain the net ionic equation which I suspect may be your next question. Write the full molecular equation and balance it. HNO3(aq)+ KOH(aq) => KNO3(aq) + H2O(l) Next step is to write those ...
May 6, 2014

Chemistry
yes
May 6, 2014

chemistry
#3 is an alkene. I don't know how you've been taught to do this but I do it this way. CnH2n+2 = alkane CnH2n = alkene (this is C20H40 and C5H10 as well as C3H6) CnH2n-2 = alkyne
May 6, 2014

CHEMISTRY HELP !!!!
I think 3 is right so it can't be D.
May 6, 2014

chemistry
heat lost by Ag + heat gained by water = 0 [mass Ag x specific heat Ag x (Tfinal-Tinitial)] + [mass H2O x specific heat H2O x (Tfinal-Tinitial)] = 0 Substitute and solve for Tf, the only unknown.
May 6, 2014

check---chemistry
Please read and correct so it makes sense.
May 6, 2014

Chemistry
You do these by noting that the formation constant is huge so that the complex essentially forms at 100%, then turn the reaction around as if it were a weak acid and calculate the (M^2+). ..........M^2+ + 6CN^- ==> M(CN)6^4- I.....0.170M....1.31M........0 C....-0.170...-6*0...
May 6, 2014

Chemistry
(P1V1/T1) = (P2V2/T2)
May 6, 2014

(5) Chemistry - Science (Dr. Bob222)
First thanks for sharing that Zn/Cu answer. I was sure that was right and as I posted last night, I might be missing something but if so I didn't see it. My equation for the buffer was 4.99 = 4.74 + log (130+x)/(100-x) 0.25 = log (130+x)/(100-x)see below 1.78 = (130-x)/(...
May 6, 2014

(5) Chemistry - Science (Dr. Bob222)
Let HA = CH3COOH millimols HA = mL x M = 1000 x 0.1 = 100 mmols A^- = 1000 x 0.13 = 130 First determine what the pH of the solution is initially using the Henderson-Hasselbalch equation. I obtained 4.85 but you should ocnfirm that. Then you want to increase that by 0.14 by ...
May 6, 2014

Chemistry - Science (Dr. Bob222)
millimols NH3 = mL x M = 100 x 0.1 = 13 mmols HCl = 87 x 0.15 = 13.05 My best guess is that these are to be considered the same since the 87 has two s.f. and 13 does too. ........NH3 + HCl ---> NH4Cl I.......13....13........0 C......-13...-13.......+13 E........0.....0...
May 6, 2014

science check answer
I think your first choice was right.
May 6, 2014

Chemistry - Science (Dr. Bob222)
mmols CH3NH2 - 0.40 x 130 mL = 52 ..........CH3NH2 + HCl ==> CH3NH3^+ I..........52.......0........0 add.................x............. C.........-x.......-x........x E.........52-x......0........x 11.59 = 10.64 + log (52-x)/(x) 8.91 = (52-x)/x 8.91x = 52-x 9.91x = 52 x = 5...
May 6, 2014

Chemistry - Science (Dr. Bob222)
Did you convert pKb given to pKa?
May 6, 2014

Chemistry - Science (Dr. Bob222)
This looks almost like the KOH/acetic acid above. If you still have trouble show what you've done and where you're stuck as well as what you don't understand and I can help you through it.
May 6, 2014

Chem Check Please!!!
I think when the cell is set up as written above (with the diagram) it means Ag + Cl^- ==> AgCl + e E = -0.222 Cu^2+ + 2e --> Cu E = 0.337 So the sum is +0.115 or c.
May 6, 2014

Chem Check Please!!!
1 is right. 2. I am not familiar with this particular series but you can read about it here. http://en.wikipedia.org/wiki/Spectrochemical_series
May 6, 2014

Chem Check Please!!!
I don't think the answer is either c or d. If the complex is diamagnetic doesn't that mean all of the electrons are paired. Doesn't that make it low spin. And if they are paired doesn't that make the delta oct difference between t2g and eg large? So I would ...
May 6, 2014

Chem Check Please!!!
I agree
May 6, 2014

CHEMISTRY HELP !!!!
Isn't that e. I think I answered this a day or so ago and for some inexplicable reason I thought it was Cr(IV) but of course Cr(II) is right.
May 6, 2014

chemistry
29.6% (w/w) is 29.6 g KCl/100 g solution. That is 29.6g KCl in (29.6g KCl + 70.4 g H2O. mols KCl = grams/molar mass = ? kg H2O = 0.0704 molality of the solution is mols/kg solvent Then delta T = i*Kb*m i = 2 for KCl. Solve for delta T and add to 100 C to find new boiling point.
May 6, 2014

Science
work is -pdV work is -0*dV = 0
May 6, 2014

chemistry
This problem is a bit confusing to me. If you've collected the H2 over water and you calculate V H2 from PV = nRT why won't the volume of the H2O be the same as the volume of H2 gas? I plugged in the numbers and obtained abou4 31 L for volume H2. Seems to me any other ...
May 6, 2014

chemistry
.....CH3NH2 + HOH ==> CH3NH3^+ + OH^- I...0.1003............0.........0.1204 C.....-x..............x..........x E...0.1003-x..........x........0.1204+x Kb = (CH3NH3^+)(OH^-)/[CH3NH3^+] Look up Kb and plug in the numbers. Solve for x = (CH3NH3^+)
May 6, 2014

chemistry
Those formula don't mean anything to me. If you write them in acid/base notation, which I suspect they are, it would be easier. At any rate, look at your post above and see if it isn't worked the same way.
May 6, 2014

chemistry
If the volume decreases (by say a factor of 2) that will double the (PH3) and double (BCl3). For a factor of 1.774 concn will be increased for EACH by 1.774. Remember the solid doesn't appear in Kc. Kc = 1/(PH3)(BCl3) So Kc > Q = 534.8/(1.774)(1.774)
May 6, 2014

chemistry
Do you mean for this reaction be be written as N2 + O2 ==> 2NO with Kc = 2400. That's the way you have your arrows.
May 6, 2014

chemistry
Substitute the equilibrium concentrations given in the problem into the Kc expression and solve for K.
May 6, 2014

chemistry
q = mols H2O x molar heat capacity x (Tfinal-Tinitial)
May 6, 2014

Chem 130
You need to find the arrow key and use it. mols CaCO3 = grams/molar mass Using the coefficients in the balanced equation, convert mols CaCO3 to mols CO2. Now convert mols CO2 to grams CO2. g = mols x molar mass
May 5, 2014

Chem 130
You have a 100 L tank and you want to fill it with He to a pressure of 155 atm at 22 C. This problem is two problems in one. One for He and the other for H2. Here is the He one done for you. It's just a matter of substituting into PV = nRT and using n for solve for grams. ...
May 5, 2014

Chem 130
Use PV = nRT and solve for n in each tank. Then n = grams/molar mass. You know molar mass and n, solve for grams in each tank.
May 5, 2014

chemistry
Ptotal = pO2 + pH2O You know Ptotal and pH2O, solve for pO2. Note Ptotal and pH2O are not in the same units.
May 5, 2014

Chem 130
Ptotal = pO2 + pH2O You know Ptotal and pH2O, solve for pO2.
May 5, 2014

Chemistry
%Z(w/w) = (g Z/total grams)*100 = ? where total grams = gX + gY + gZ
May 5, 2014

Chemistry
dHsurr = -dH/T
May 5, 2014

Chemistry
Is that 2.6M HCl? I will assume so. Zn + 2HCl ==> ZnCl2 + H2 How many mols H2 is that? Ptotal = 845 torr pH2O at 65C = approx 190 torr. You need to look up this value in your text/notes because I've estimated it from some tables I have. pH2 = 845-190 = about 655 mm or ...
May 5, 2014

Chemistry
See your other post.
May 5, 2014

Chem 130
mols He = 2.03/molar mass He = n1 mols He = 6.19/molar mass He = n2 (n1/12L) = (n2/xL) Solve for x L.
May 5, 2014

Chemistry
............MgF2 ==> Mg^2+ + 2F^- I...........solid.....0.......0 C...........solid.....x.......2x E...........solid.....x.......2x Ksp = (x)(2x)^2 You know x = 2.3E-3M.Substitute and solve for Ksp.
May 5, 2014

Chemistry
Let's call aniline BNH2 ...........BNH2 + HOH ==> BNH3^+ + OH^- I..........0.201...........0........0 C...........-x.............x........x E.........0.201-x..........x........x Kb = (BNH3^+)(OH^-)/(BNH2) You know x. Substitute into Kb expression and solve for Kb.
May 5, 2014

Chemistry - Science (Dr. Bob222)
I worked through it and came up with 1.09v also. 1.13 seems to be the closest ad I would go with that. Sometimes answer sheets give approximate answers and this could be one of them. If I'm missing something I don't see it.
May 5, 2014

chemistry
Use PV = nRT and solve for P (in atmospheres) and convert to mm Hg. 1 atm = 760 mm Hg. Don't forget T must be in kelvin.
May 5, 2014

Organic CHM II
http://lipidlibrary.aocs.org/Lipids/tag2/index.htm
May 5, 2014

chemistry: please check work
I agree with the procedure as well as the value and the number of significant figures.
May 5, 2014

Chemistry
http://en.wikipedia.org/wiki/Delocalized_electron
May 5, 2014

chemistry
What do you need help with? The lower concn will be the increasing and the higher concn will be decreasing until both have the same concn. So you know the lower concn will be oxidized and the higher concn will be reduced.
May 5, 2014

Chemistry
No, of course you don't know the final T. That's what you're trying to find. It ways that in the problem, "What is the final T if ..." heat lost by Ni + heat gained by H2O = 0 [mass Ni x specific heat Ni x (Tfinal-Tinitial)] + [mass H2O x specific heat ...
May 5, 2014

Chemistry
You can but that's the hard way to do it. It is much easier to substitute the individual numbers and work it out by pieces.
May 5, 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
May 5, 2014

Chemistry
You want 1 mol SO3 and not 2 so divide by 2. You want the reverse so change the sign.
May 5, 2014

Chem Check Please!!!
I disagree with 1. I agree with 2,3,4. I con't see all of the name typed on 5 but e is right if that is chromium IV.
May 5, 2014

Chemistry
It's twice dHof
May 5, 2014

Chemistry
zero or very low
May 5, 2014

Chemistry
Take equation 1 and add it to the reverse of equation 2 and add that to the reverse of 1/2 equation 3. When reversing dH, change the sign. When taking 1/2 equation, also take 1/2 dH.
May 5, 2014

chemistry
Q = coulombs = amperes x seconds Q = 0.680A x 20m x (60s/m) = ? = about 816 96,485 coulombs will deposit (63.54/2)g Cu. You have 816 coulombs; therefore, 63.54/2 x (816/96,485) = about 0.3g if I punched the right buttons.
May 5, 2014

Underwater explosion
Other tutors may wish to weigh in on this question but I think the answer is yes IF the timing is just right and the compressed air force can be sustained long enough.
May 5, 2014

Chem
This is an example of a back titration; i.e., the KI/KIO3 produces I2, the I2 reacts with some of the vit C, the excess I2 is titrated with thiosulfate. 6H^+ + I^- + IO3^- ==> 3I2 + 3H2O Then vitC + I2 ==> 2I^- + vitCx mols IO3 added initially = M x L = 0.025 x 0.01988...
May 5, 2014

chemistry
The question isn't exactly clear; it isn't clear that it is the greatest amount of acid per grams antacid or per mol antacid. H^+ + OH^- ==> H2O So the one with the largest OH per mol will neutralize the most acid. That is Al(OH)3. And you don't capitalize ...
May 5, 2014

chemistry
Wouldn't that be 100g/5 dm^3 = 20g/dm^3
May 5, 2014

Chemistry
No, the problem says to write the equilibrium constant expression. Nothing about finding the value of K.
May 5, 2014

Chemistry
What is your problem with these. Keq expressions are the same. K = (products)^x/(reactants)^y and raise each substance to the power indicated by the coefficient.
May 5, 2014

chemistry
How many mols do you want? That's M x L = ? Then mols = grams/molar mass. You know molar mass and mols, solve for grams.
May 5, 2014

chemistry
mols acetic acid = grams/molar mass, then M acetic acid = mols/L
May 5, 2014

chemistry
M = mols/L
May 5, 2014

chemistry
See your post above.
May 5, 2014

Chemistry
Yes you do exactly what you have outlined. I would look at change in C and change in O for n. If we see ethanol as C2H6O and assign oxiatioin states of -2 for O and +6 for 6H, that makes 2 C in ethanol as -4. On the right the 2C are +8 so the change in e is 12. We can check ...
May 5, 2014

chemestry
I suggest you google these terms.
May 5, 2014

Chemistry
Same process. Write the balanced equation. Convert g CO2 to mols with mols = grams/molar mass. Use the coefficients to convert mols CO2 to mols HCl. Then M HCl = mols HCl/L HCl.
May 5, 2014

Chemistry
Na2CO3 + 2HCl ==> 2NaCl + H2O + CO2 mols Na2CO3 = M x L = ? Using the coefficients in the balanced equation, convert mols Na2CO3 to mols HCl. Then the defintion of M HCl = mols HCl/L HCl. You know M and mols, solve for L.
May 5, 2014

science
L1 x %1 = L2 x %2 ?L x 0.8% = 0.5L x 9% ?L = ?
May 5, 2014

what is the answer
Set up a ratio and proportion. (feet/shadow) = (feet/shadow) (8.1/24.3) = 20.1/x) Solve for x.
May 4, 2014

chemistry
The temperature at which water boils at high altitudes is lower than the temperature it boils at lower altitudes. Therefore, when cooking on a high mountain the water may boil 98 instead of 100 C so you should boil it (less, more). 2. Water boils when water boils. Turning up ...
May 4, 2014

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