Saturday
February 28, 2015

Posts by DrBob222


Total # Posts: 47,301

chemistry
Using the coefficients in the balanced equation lets you convert mols of mols of anything to anything in the equation. mols KCl = grams/molar mass = approx 5 but that's an estimate. 5 mols KCl x (3 mols O2/2 mol KCl) = 5 x 3/2 = ? mols O2. Then grams = mols o2 x molar mass...
February 25, 2015

Chemistry
pCO = (1348/760) = approx 1.8 atm but you need to do it more accurately. pH2O = 1780/760 = approx 2.3 atm. .........CO(g)+H2O(g)⇌CO2(g)+H2(g) I.......1.8....2.3.....0......0 C.......-x......-x.....x......x E......1.8-x...2.3-x...x......x Substitute the E line into Kp ...
February 25, 2015

AP Chemistry
a. rate = k(A)^2(B)^3 c. If A is doubled 2^2 = 4 so rate is 4x. d. If B is doubled 2^3 = 8 so rate is 8x. e. You get the idea
February 24, 2015

Chemistry
Remember how to work this type stoichiometry problem. Step 1. Convert what you have (in this case TiCl4) to mols. mols = grams/molar mass Step 2. Using the coefficients in the balanced equation, convert mols of what you have to mols of what you want(in this case Ti). With the ...
February 24, 2015

Chemistry
Wouldn't that be 12 cm - 4.92 cm = ? The one component with RF value of 1.0 means it is at the solvent front of 12 cm as you calculated and that is 12 cm. The other one is at 4.92. . zero cm | |x 4.92 cm | | | | +x 12 cm solvent front and one component.
February 24, 2015

Chemistry
Yes, the RF value is the ratio of the distance the solute moved to the distance the solvent front moved; so 0.41 = x distance/12 x = 12 x 0.41 = ? cm
February 24, 2015

chemistry
mols KHP = grams/molar mass mols OH = mols KHP since the equation is 1:1
February 24, 2015

chemistry
I don't understand the question. Perhaps another tutor will.
February 24, 2015

honors chemistry
Partly yes and partly no. All of the materials will give you the same number of particles except NaCl will be twice the others. # molecules will be 10 x 6.0E23. For NaCl # ions will be 2 x 10 x 6.02E23. For NaCl I'm assuming it will be in whatever form that allows us to ...
February 24, 2015

honors chemistry
No. mols = grams/molar mass. Since the molar mass of each of those substances is different then the number of mols must be different. And if the number of mols is different then mols x 6.02E23 will be different for the number of particles. The number of particles (ions) for ...
February 24, 2015

chem
And you know how to do what parts? Show your work and explain what you don't understand about those parts you need help with.
February 24, 2015

chemistry
I think something is amiss in this problem. Let's go the other way. mols C = 1/12 = 0.083333 mols H = 0.033597/1.00794 = 0.03333 ratio is C2.48 to H1.00 which rounds to C5H2 and this is an unlikely hydrocarbon. So I don't think all of the looking in the world will help.
February 24, 2015

chem
Fe2(SO4)3 + 3Ba(OH)2 => 2Fe(OH)3 + 3BaSO4
February 24, 2015

Science
ccw. counterclockwise
February 24, 2015

chemistry
What an interesting problem. I don't think I've seen anything like this in my entire career. I'll get you started. wt% = 2.87 which means 2.87 g solute/(100 g solution)]*100 = 2.87 That is [(2.87g solute)/(2.87 solute + 97.13 g C6H6)]* 100 So we multiply by 10 to ...
February 24, 2015

Chemistry
You didn't explain anything. My assumption is that for #1 you are taking 2 mL of the stock solution and adding 8 mL distilled H2O and you want to know the concentration of the final solution when you start with that 2 mL of 7.03 umol/L. Again, I assume you want it in umol/...
February 24, 2015

Chemistry
You need to explain this a little better; I don't know what you're asking. I understand the 7.03 umol/L is what you have but I don't know what you're to do with it. What's the 2,8,4,6,6,4 mean?
February 24, 2015

Chemistry 101
Go back and look at the NaCl/Cl2/H2 problem you posted earlier. Those steps are the same for solving this problem. If you need help show where your trouble is and we an help you through.
February 24, 2015

Science
I disagree with A. It's true that methane is a gas but I think that's a secondary issue. Its flammability is what you are talking about.
February 24, 2015

Chemistry
C = 31.57% H = 5.30% Therefore, O = 100%-31.57-5.30 = about 63%. Take a 100g sample which will give you 31.57g C atoms. 5.30g H atoms. 63g O atoms. Convert to mols and I'll estimate. 31.57/12 = about 2.63 mols C 5.30/1 = 5.30 mols H 63/16 = about 3.94 mols O Now find the ...
February 24, 2015

Chemistry
heat gained by ice + heat gained by melted ice + heat lost by 75 mL liquid H2O = 0 (mass ice x heat fusion) + (mass melted ice x specific heat liquid H2O x (Tfinal-Tintial) + (mass 75 mL H2O x specific heat liquid H2O x (Tfinal-Tinitial) = 0 Substitute all of the numbers and ...
February 24, 2015

Chemistry
I think for part 1 they want grams. Your 1.39 mols Cl2 is right; just multiply by molar mass Cl2. part 2. H2 done the same way you did #1. mols NaCl = 163/58.44 = ? mols H2 = 1/2 that from the balanced equation. grams H2 = mols H2 x molar mass H2 which is 2 g/mol. #2. P4(s) + ...
February 24, 2015

chemistry
See below
February 24, 2015

chemistry
It is wrong but only in places and I don't understand why you made those errors. molecular equation is H2SO4(aq) + 2NH4OH(aq) ==> (NH4)2SO4(aq) + 2H2O(l) CIE: 2H^+(aq) + SO4^2-(aq) + 2NH4^+(aq) + 2OH^-(aq) ==> 2NH4^+(aq) + SO4^2-(aq) + 2H2O(l) NIE: 2H^+(aq) + 2OH^-(...
February 24, 2015

Just a question
From a purely practical standpoint, my son received a B. S degree in mass communication, signed on with a newspaper as a part time reporter, became a full time, and finally an editor of a small newspaper. With the right connections and a good grasp of the English language and ...
February 24, 2015

Chemist
a. rate = k(NO)^2(Cl2) b. The order of the equation is 2+1 = 3
February 24, 2015

science
Yes, I suppose one could build a 1 square mile enclosed area and stick a vacuum pump on it. Or for that matter, there are many square miles of space above the atmosphere without any oxygen and no enclosure is required. But as for moving that "particular" part of ...
February 24, 2015

To B.
Stop trying to be funny. You're almost spamming the board. You are't offering any solutions and you're taking up time and space. Cut it out. You COULD be banned from this site and you may want/need to use this site one of these days.
February 24, 2015

Math
Don't be ridiculous. Or something like 2+2 = 10-6?
February 24, 2015

Chem 111
React with what?
February 23, 2015

chemistry
1. millimols = mL x M = 5 mL x 0.002M = 0.01 mmols or 1E-5 mols. mols SCN = same 2. ...........Fe^3+ + 2SCN^- ==> Fe(SCN)2^+ I..........1E-5....1E-5........0 C...........-x......-2x........x E.........1E-5-x...1E-5-2x......x x from the problem is 3E-4M and that x 0.01L (10 ...
February 23, 2015

To B.
Stop trying to be funny. You're almost spamming the board. You aren't offering any solutions but you're wasting time and using up space so cut it out. You COULD be banned from this site but think about it. You may want/need this site some day, especially if you ...
February 23, 2015

Chemistry
q = mass Cu x heat fusion Cu
February 23, 2015

chem
2AgNO3 + Na2CO3 ==> 2NaNO3 + Ag2CO3(s) Before we can do anything you must identify 3.10 what and 4.43 what. This is a limiting reagent problem (LR) and you know that because amounts are given for BOTH reactants. I work these the long way. I will assume those are grams. mols...
February 23, 2015

chemistry
heat lost by object + heat gained by water = 0 [mass object x specific heat object x (Tfinal-Tinitial)] + [mass H2O x specific heat H2O x (Tfinal-Tinitial)] = 0 Substitute the numbers from the problem and solve for specific heat object.
February 23, 2015

To B.
I don't know but Dawn said use only addition and subtraction and that's what I did.
February 23, 2015

3rd grade math
B= ride bikes W = walk D = driven to school ================== W = B+6 B = D W + B + D = 24 For D you can substitute B For W you can substitute B + 6 Do that and solve for B.
February 23, 2015

Math
If you add units to it and watch the number of significant figures, yes. The proper unit is cc (cubic centimeters)
February 23, 2015

Math
What's confusing about l*w*h/3 ?
February 23, 2015

5th grade math
You want one side to be s and the other side 1.6s s*1.6s = 360 Solve for s and 1.6s 15 and 24?
February 23, 2015

Chemistry
mols O2 = 8.58E21/6.02E23 = ? Using the coefficients in the balanced equation, convert mols O2 to mols FeCl2. That's ? mols O2 x (4 mols FeCl2/3 mols O2) = ? Then M FeCl2 = mols FeCl2/L FeCl2. You know M and mols, solve for L
February 23, 2015

chemistry
mmols FeCl2 = mL x M = ? mmols KOH = 2x mmols FeCl2 M KOH = mmols KOH/mL KOH. You know mmols kOH and M KOH, solve for mL KOH.
February 23, 2015

chemistry
dE = q + w w = -346J from the problem. dE increased by 6365 J. Solve for q Then q = mass x specific heat x (Tfinal-Tinitial) Substitute and solve for sp. h.
February 23, 2015

chemistry
q = mass H2O x specific heat H2O x (Tfinal-Tinitial) You had 0.310 x 0.06 = about 0.0186 mols Ba(OH)2 and that produces 2 mols H2O. dHrxn = q/0.0186 and divide that by 2 to find per mol H2O.
February 23, 2015

Chemistry
You change the sign of qcombustion rxn so that qcal = -qrxn. qcal = Ccal x delta T q = 3949*1.331/141.44 = ? Then ? = Ccal*delta T. Solve for Ccal.
February 23, 2015

Chemistry
q = heat released = heat cap x delta T q = 38.5 kJ/K x 2.93 = approx 113 kJ but you need a better answer than my estimate. That's approx 113 kJ/5.80 g candy bar = approx 19 kJ/gram. I would then convert 19 kJ/g to J/g, then to calories (that's with a small c) using 4....
February 23, 2015

chemistry
You're only choice is to work the problem and see. This is a limiting reagent (LR) problem and you know that because amounts are given for BOTH reactants. I work these the long way. 2Na(s) + Cl2(g) = 2NaCl(s) mols Na = grams/molar mass mols Cl2 = grams/molar mass Using the...
February 23, 2015

science
http://education.nationalgeographic.com/education/encyclopedia/weathering/?ar_a=1
February 23, 2015

Solution Making
That looks ok to me.
February 23, 2015

life orientation
http://brainly.com/question/305722
February 23, 2015

Chemistry
I think the m.p. of group I and group II elements are lower than the transition metals. As for the second part, I don't know unless metals with m.p. close together tend to solidify at one time while those of widely different m.p. might segregate during cooling. The Fe, Co...
February 23, 2015

Chemistry
sp g. = density HAc/density H2O 1.040 = (density HAc)/(0.9956 g/ml) solve for density HAc
February 23, 2015

CHEMISTRY
Change in color of the indicator. Formation of ppt In some cases dissolution of ppt. Formation of gas (often CO2 with carbonate samples)
February 23, 2015

CHEMISTRY
Looks ok to me.
February 23, 2015

chemistry
Dalton's law of partial pressures. The total is the sum of each. ptotal = pH2 + pAr + pHe
February 23, 2015

AP Chem
I believe Bob P counted the H atoms wrong. It's 10 from the (N2H5)2 and 4 more from the other part of the formula for a total of 14 and not 22.
February 22, 2015

chemistry
I don't see anything wrong with this. I would have used the HH equation but what you used is perfectly ok. In fact, if you substitute those values into the HH equation you get a pH of 6.999 which should be ok. pH = 7.20 + log(96.6/153.4) = 6.999 which rounds to 7.0 and ...
February 22, 2015

Chemistry
What's the problem with taking 15 mL of the regular household bleach and adding salt water to make 30 mL of solution. That will dilute the initial bleach by a factor of 2 and it will be just 1/2 what you started with.
February 22, 2015

Chemistry
I've answered this before. Use the Henderson-Hasselbalch equation. You don't get anywhere by just recopying the problem; however, if you show what you're tried and/or tell us what you don't understand about the solution we should be able to help you thorough it.
February 22, 2015

Chemistry
heat lost by Fe + heat gained by water = 0 [mass Fe x specific heat Fe x (Tfinal-Tinitial)] + [mass H2O x specific heat H2O x (Tfinal-Tinitial)] = 0 Substitute and solve for mass H2O
February 22, 2015

Chemistry
Kp = Kc(RT)^delta n. Solve for Kc. Convert 1 g SO2 and Cl2 to mols/L Calculate Qc and compare that with Kc. Post your work if you get stuck.
February 22, 2015

Chemistry
(NOBr) = 0.782 mols/100L = approx 0.008 but you need to do it more accurately as well as all of the othr values I've estimated. .......NOBr(g) ↔ NO(g) + 0.5Br2(g) I......0.008......0..........0 C......-x.........x.......0.5x E.....0.008-x.....x.......0.5x Substitute ...
February 22, 2015

Chemistry
You change the T of 100 g water by 10 C. So how much will T change for 200 g water? Could that be 5 C?
February 22, 2015

chemistry
heat added to melt ice + heat gained by water from ice + heat lost by 125 mL H2O = 0 (22.7g ice x heat fusion) + (22.7 g H2O x 4.184 x (Tfinal - Tinitial) + (125 x 4.184 x (Tfinal-Tinitial) = 0 I get approx 11 degrees C. Solve for Tfinal.
February 22, 2015

Chemistry
I answered this before and I told you how to work the problem. You don't need mols. The heat produced by the reaction is q = mass x specific heat x delta T. You know mass (160g), you know specific heat, and you know delta T. You don't need mols if you use mass in grams...
February 22, 2015

chem
Use the Henderson-Hasselbalch equation.
February 22, 2015

chem
1. PV = nRT 2. PV = nRT and n = grams/molar mass 3. PV = nRT 4. {V = nRT 5. mols = grams/molar mass, then mols x 22.4L/mol at STP 6. PV = nRT, then n = grams/molar mass. Remember in these problems that if you you atmospheres for pressure then R is 0.08206. If you use P in kPa...
February 22, 2015

Chem - Oxidation States
1. compounds must have zero charge. 2. ions must have charge on the ion. 3. oxidation states in the compound/ion must add to the charge. For SeO4^2-, youhave O is -2 and 4*-2 = -8 so Se must be +6 t leave a charge of -2 on the ion. For H2S, H is +1, 2*+1 = +2 so S must be -2. ...
February 22, 2015

Chemistry
80 mL + 80 mL = 160 mL aqueous solution. If you assume the density is the same as that of water;i.e., 1.00 g/mL, than the mass is 160 grams.. The specific heat h2O is 4.184 so q = 160 x 4.184 x 2.5 = ? in J. BTW, I think you meant NH4OH (and technically that is NH3(aq)
February 22, 2015

Chemistry
Why didn't you show your work. Then we could find the trouble in an instant. Use (P1V1/T1) = (P2V2/T2) and remember T must be in kelvin.
February 22, 2015

chemistry
mols C2H5OH = grams/molar mass = ? mols CH3COOH = grams/molar mass = ? ..C2H5OH + CH3COOH ==> CH3COOC2H5 + H2O I..0.18......1.0.........0...........0 C...-x.......-x..........x...........x E.0.18-x....1.0-x........x...........x 49.74/60 = about 0.829 so 1-x = 0.829 which ...
February 22, 2015

Chemistry
I answered this about 1-1/2 hours after you posted the first time. Look for your post at 5:43
February 21, 2015

Chemistry
Use the Henderson-Hasselbalch equation.
February 21, 2015

chemistry
q = mass x specific heat x dT 3.5E3 = 0.07mol x 254 J/k*mol x dT Solve for dT. Check your problem and make sure that is J and not kJ (both places where you have J).
February 21, 2015

chemistry
C4H10 + Br2 + no light ==> No reaction. C4H10 + Br2 + light ==> C4H9Br + HBr light catalyzes the reaction. The color of the Br2/CCl4 solution faded because the Br2 was used.
February 21, 2015

science
It is transferring from particle to particle and travels that way. But each transfer is not 100% and it gradually dies out.
February 21, 2015

chemistry
You should find the arrow key on your computer and use it. When using gases at the same T and P one can use a shortcut procedure in which the volume (in L) is used directly as if it were mols. So all you need to do is to convert 120 L H2S to SO2. 120 L SO2 x (2 mols SO2/2 mols...
February 21, 2015

chemistry
First, note the correct spelling of celsius. Ptotal = pdry ethene + pH2O@17 Ptotal = 680 mm + 14.0 = ? mm
February 21, 2015

chemistry
Do you know how to determine the oxidation number for N in these compounds? I'll do the first two for you. #1 rule. Compounds or elements have a charge of zero. #2 rule.The oxidation state of all of the elements in the material must add to zero (if it's a compound) or ...
February 21, 2015

chemistry
Fe2O3 + 3CO ==> 3CO2 + 2Fe mols Fe2O3 = grams/molar mass = ? Use the coefficients in the balanced equation to convert mols Fe2O3 to mols CO. Now convert mols CO to grams. grams CO = mols CO x molar mass CO
February 21, 2015

science
C isn't right. The best answer you have is B but I wouldn't stick my neck out until you finish the sentence for D. Heat capacity is an extensive property which means it depends upon HOW MUCH of the material is present. So it obviously takes more heat to raise the T of ...
February 21, 2015

Chemistry
I think you're there if you correct the typo in your next to last step. That 8.20M should be 8.10 M so you get a slightly different factor and that x 124 mL will give you the right answer.
February 21, 2015

chemistry
My best guess is no but I can't calculate that no answer without Ksp values for the two materials at whatever temperature you mean by "cold".
February 21, 2015

chemistry
w = nRTln(V2/V1) and since work is being done on the gas the sign of w is +.
February 21, 2015

Chemistry
1. mols = grams/molar mass = ? 2. Convert 6.0 mg to grams. Then mols cisplatin = grams/molar mass = ? # molecules cisplatin = mols x 6.02E23 = ? # Cl atoms will be twice that since there are two Cl atoms/molecule of cisplatin.
February 20, 2015

Chemistry AP
Thanks for the reminder. I don't think you have approached the problem right (at least not completely right). I'll redo some of what you've described. You have the mmols right. .......NH3 + HCl ==> NH4Cl I......1.5....0.......0 add...........4............ C...
February 20, 2015

Chemistry
delta T = i*Kf*m delta T = 4.37 C. You might want to make that 4.38 to add just a wee bit more. i for NaCl = 2 Kf for water = 1.86 Substitute and solve for m = molality Then m = mols/kg solvent You know m and kg (30) solvent. Solve for mols. Then mol = grams/molar mass You ...
February 20, 2015

Chemistry
volume = mass/density Look up the density of brass, substitute and solve for volume. mass is 100 g. The add the volume of the brass to the volume of the water (50 mL) and that will be the new reading of the water level. I don't know what height that is; I'm assuming ...
February 20, 2015

Chemistry
What are you doing wrong? You're using gauge pressure (psig) and not "real" pressure (psia). What you want to do is to convert gauge pressure to absolute (real) pressure, use P1V1/T1 = P2V2/T2, solve for new P2, convert back to gauge. pgauge + 14.7 = pabsolute ...
February 20, 2015

chemistry
Al2(SO4)3 + 6NaOH ==>3Na2SO4 + 2Al(OH)3 mols Al2(SO4)3 = grams/molar mass = ? mols NaOH = grams/molar mass Using the coefficients in the balanced equation, convert mols Al2(SO4)3 to mols Al(OH)3. Do the same and convert mols NaOH to mols Al(OH)3. It is likely that the two ...
February 20, 2015

Chemistry
It would help if I knew what you don't understand about this. Also it would help if you found and used the arrow key(s) To write the net ionic equation you balance the molecular equation (which happens to be A) as step 1, for step 2 convert the molecular equation into a ...
February 20, 2015

chemistry
M = mols/L You want 1 L of 0.5M so you want 1 x 0.5 = 0.5 mols. grams for 0.5 mol = mols x molar mass = ? Weigh that many grams CoCl2.6H2O, add to a 1 L volumetric flask, add some water, swirl to dissolve the solute, add DI water to the mark on the flask, mix thoroughly, stopper.
February 20, 2015

Chemistry
C3H8 + 5O2 ==> 3CO2 + 4H2O When using gases at the same T and P, one can take a shortcut and use liters as if they were mols. For the problem we simply convert L of one thing into L of the other. 0.7L C3H8 x (5 mols O2/1 mol C3H8) = ? L O2 required. The other parts are done...
February 20, 2015

chem
mols nicotine = grams/molar mass = ? mols C6H12 = grams/molar mass Find total mols. XC6H12 = nC6H12/total mols. M C6H12 = mols C6H12/L solution = ?
February 20, 2015

chemistry
LiClO4 --> LiCl + 2O2 mols LiClO4 = grams/molar mass Using the coefficients in the balanced equation, convert mols LiClO4 to mols O2. Now use PV = nRT and convert mols O2 to L at the conditions listed. Remember T must be in kelvin. If you use kPa for P you must use 8.314 ...
February 20, 2015

Chemistry
dG = dH - TdS. You know dH is - You know dS is + (because there are 6 mols gas on the left and 10 on the right; an increase in mols of gas is an increase in S.) From the above equation if dH is - and dS is +, the term -TdS will be - no matter what T is used so dG will be - at ...
February 20, 2015

Chemistry
I disagree also.
February 20, 2015

science
Can you see it burn?
February 20, 2015

chemistry
http://en.wikipedia.org/wiki/Naphthalene http://en.wikipedia.org/wiki/Benzoic_acid
February 20, 2015

chemistry
Ba(OH)2 + 2HCl ==> 2H2O + BaCl2 q = mass H2O x specific heat H2O x (Tfinal-Tinitial) = delta H. mols HCl = 0.065 x 0.660 = 0.0429 mols delta H in J/mol = q/0.0429 = ?
February 20, 2015

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