Saturday
August 1, 2015

Posts by DrBob222


Total # Posts: 49,602

Chemistry
mols NiCl2 = M x L = ? mols NaOH = 2 x mols NiCl2. M NaOH = mols NaOH/L NaOH. You know mols and M NaOH, solve for L and convert to mL.
July 20, 2015

GT
A. Expansion work (or PV work) is work = -p(v final-v initial) If p is zero, the PV work must be zero since any number x zero is zero. B. Substitute the numbers into -p(v final - v initial). p is 1.5 for B and 2.8 for C. Delta V is 89.3 - 26.7 = ? mL and change that to L. Work...
July 20, 2015

chemistry
p of gas C = nRT/V. Substitute and solve for pressure of gas C. Then Ptotal = pA + pB + pC = about 1.35 atm.
July 20, 2015

Science
When I read the question it says "the following processes" but then (a) is a statement and not a process. We know PV = k
July 20, 2015

Science
Part of this question appears to be missing.
July 20, 2015

Chemistry
H2SO4 + 2KOH ==> K2SO4 + 2H2O mols KOH = M x L = ? Using the coefficients in the balanced equation, convert mols KOH to mols H2SO4. Then M H2SO4 = mols H2SO4/L H2SO4.
July 20, 2015

Chemistry
It takes 540 calories to change 1 g H2O from liquid to steam at 100 C. 540 cal/g x #g = 5400 cal. Solve for #g
July 20, 2015

chemistry
heat lost by warm water + heat gained by cold water = 0 [mass warm water x specific heat H2O x (Tfinal-Tintial)] + [mass cool water x speicif heat H2O x (Tfinal-Tinitial)] \ 0 Substitute and solve for Tfinal.
July 20, 2015

org chem
We can't draw diagrams on this forum; I suggest you Google these four substances and you can get pictures/structural formulas there. If you have access to a model kit you can makes these out of ball and stick pieces and sometimes that helps you see the three dimensional ...
July 20, 2015

Science Thermochemistry
It will be 2.5 x heat for 1 mol.
July 19, 2015

organic chemistry
https://en.wikipedia.org/wiki/Phosphorus
July 19, 2015

Organic Chemistry
Use the Henderson-Hasselbalch equation. pH = pKa + log (base)/(acid) (base) is with proton off and (acid) is with proton on. When (acid) = (base), you see log is 0 and pH = pKa. Substitute a value for pH and see which ratio (base)/acid or acid/base is higher to get the other ...
July 19, 2015

science, chemistry
How about 1 batch made with brown sugar only, another batch with 3/4 brown and 1/4 granulated, another batch with 1/2 and 1/2, another batch with 1/4 brown and 3/4 granulated and a final batch with all granulated. Then compare the cookies.
July 19, 2015

organic chemistry
The best answer I could find with diagrams and prose explaining them. https://en.wikipedia.org/wiki/Butanol
July 19, 2015

Chemisty
Use the dilution formula. mL1 x M1 = mL2 x M2 70 x 0.4 = mL2 x 0.100 mL2 = 70 x 0.4/0.100 = 280 mL. So the FINAL volume must be 280 mL. ASSUMING the volumes are additive (technically they are not but at these concentrations there will not be a measurable difference) so you ...
July 18, 2015

Chemistry
This is an exercise in conversions. a. Convert 112 km to miles, then distance = rate x time. Substitute distance in miles, rate = 65 mph, solve for time in hours. b. Convert 28 miles to km and gallon to liters. Then km/L x #L = 112 km. Solve for #L.
July 18, 2015

chemistry
Both are strong acids. mols HBr = M x L = ? mols HCl = M x L = ? Total mols = sum of the two. M acid = total mols/total L and that is the molarity of the (H^+). Then pH = -log(acid)
July 17, 2015

science
Do you have a graph or table showing the solubility of KNO3 in water at 60 C? The question can be answered with that information; without it no.
July 17, 2015

chemistry
I suppose so; isn't almost anything related to thermochemistry? But what's the point of the question?
July 16, 2015

chem
psoln = XH2O*PoH2O 81.6 = XH2O*92.6 XH2O = 81.6/92.6 = approx 0.88 but you need a more accurate number than that estimate. Set up mole fraction expression for H2O. [nH2O/(nH2O + nCaCl2)] = 0.88 nH2O = 1 in the problem;solve for nCaCl2 (as ions) and I get about 0.135. The van&#...
July 16, 2015

Chemistry
I would be better if you used the same screen name. Apparently there is no standard Kh. I will use the one that is p = Kc*C but C = K*pgas is also used. p is 3340-680 mm. Convert to atm. Kc is the constant. C is the molarity. You will want mols = grams/molarmass and M = mols/L...
July 16, 2015

science
You need to be more specific about what you want. Libraries are full of books on chemistry. Huge subject area.
July 16, 2015

Physical Science
heat lost by Fe ball + heat gained by H2O = 0 [mass Fe x specific heat Fe x (Tfinal-Tinitial_)] + [mass H2O x specific heat H2O x (Tfinal-Tinitial)] = 0 You don't know Tf and Ti but you can replace those with delta T which is 2 for H2O and -18.6 for Fe.
July 15, 2015

chemistry
CH4 + 2O2 ==> CO2 + 2H2O mols CH4 = grams/molar mass = ? Using the coefficients in the balanced equation, convert mols CH4 to mols O2. Now convert mols O2 to L O2 by mols O2 x 22.4 L/mol = L O2.
July 15, 2015

chemistry
10.5% w/w means 10.5 g sucrose in 100 g solution. So how much is in 1,500 g solution? (g solute/g solution)*100 = % (g solute/1500)*100 = 10.5 Solve for g solute.
July 15, 2015

Chemistry
2NaOH + H2C2O4 ==> Na2C2O4 + 2H2O mols H2C2O4 = M x L = ? Using the coefficients in the balanced equation, convert mols H2C2O4 to mols NaOH (that's mols NaOH = 2 x mols H2C2O4). Then g NaOH = mols NaOH x molar mass NaOH. Finally, (g NaOH/mass sample)*100 = %NaOH
July 15, 2015

Chemistry
You start by writing an equation. 2NaOH + H2C2O4 ==> Na2C2O4 + 2H2O mols H2C2O4 = M x L = ? Using the coefficients in the balanced equation, convert mols H2C2O4 to mols NaOH. Then M NaOH = mols NaOH/L NaOH
July 15, 2015

chemistry
PbO is not soluble in HCl and what little dissolves forms PbCl2 directly (but only in small amounts) and that sticks to the surface and impedes the production of more PbCl2. It isn't that it can't be prepared; it's just that it can't be prepared in larger ...
July 15, 2015

Chemistry
Your answer for c is right. The equations below should help with a and b. Cu(IO3)2 ==> Cu^2+ + 2IO3^-; i.e., 1 mol Cu(IO3)2 produces 2 mols IO3^- IO3^- + 8I^- + 6H^+ ==> 3[I3]^- + 3H2O
July 15, 2015

chemistry
How many mols NaCl do you want in the 100 mL? That's M x L = 4M x 0.1L = 0.4 mols. How many grams is that? That's mols = grams/molar mass. You know molar mass and mols, substitute and solve for grams. Place that amount NaCl in a 100 mL volumetric flask, add DI water, ...
July 14, 2015

Chemistry
I believe you should have written the 45.5 as 45.5 psia if it is 30.6 psi. Use PV = nRT For P convert 45.5 to atm. Remember to convert T to kelvin. Solve for n. Post your work if you get stuck.
July 14, 2015

Science
q = mass marshmallow x specific heat x (Tfinal-Tinitial). You have the mass and specific heat and Ti. You will need to supply Tf; I wonder why you have it in an liquid N2 bath to begin with.
July 14, 2015

organic chemistry
How can we help you with this assignment. Books have been written on this.
July 14, 2015

Chemistry
The ? is 112 km.
July 14, 2015

Chemistry
You need to convert 28 miles to km and gallon to liters, then (km/L) x #L = ?
July 14, 2015

chemistry
Na2CO3 + 2H^+ ==> 2Na^+ + CO2 + H2O The pH must be <7.0
July 14, 2015

Thermodynamics
I gave you a link that is a calculator to do this for you. Are you telling me you can't type in 80 for the depth, hit the units bar and select feet, hit the calculate button and you get a psi in atm but you can hit the units bar again and choose psi. It shows 50.3.Or have ...
July 13, 2015

Thermodynamics
Here is a calculator for you. http://www.calctool.org/CALC/other/games/depth_press
July 13, 2015

math
Here is the SYSTEM for doing ALL conversions. 118 ft to yards. 118 ft x factor = yards The factor is EITHER 1 yd/3ft or 3ft/1 yd. All you need to do is to decide which one of those factors to use. If you guessed you would be right 50% of the time. If you reason it out you will...
July 13, 2015

Chemistry
I think the proper way to do this is to graph the data and extrapolate to 150 C. If you want to do it by a non-graphical method do this. First, determine the k for P1/T1 = k. 726/283 = 2.565 750/293 = 2.56 800/313 = 2.56 etc to the end. Average all of those k values, then k*T...
July 13, 2015

Chemistry/Physics
The answer depends upon where the temperature is now. Assuming it is solid lead to solid lead (that is it does not go through a melting range or boiling range), it is q = mass Pb x specific heat x 20
July 13, 2015

School of Christ International, physics
You really need to do a better job of writing your post. 22.0 m what. Is that cubic meter volume, or something else. What is the new nitrogen gas what? pressure? volume? temperature. I agree with Steve. In all likely hood it still is nitrogen gas. If that is volume, then (V1/...
July 13, 2015

chemistry
mass = volume x density Substitute and solve for volume.
July 12, 2015

CHEMISTRY HELP
What in the world is an hao? I assume S 16 is Sulfur 16.
July 11, 2015

organic chemistry
It looks ok to me. Draw out the 2,5 octadiene part, tack on the ethyl group on carbon 4, then count the longest chain. It is 8. Counting the ethyl group carbons it is 6 one way and 7 the other which doesn't alter the initial name of octa for 8.
July 11, 2015

organic chemistry
It's tough to do on the web. The easiest way is to draw out the acetylene, add the isobutyl and tert pentyl groups (you don't have numbers telling you where to put those groups), then add H atoms to each C to make four bonds total. Then count the H atoms.
July 11, 2015

chemistry
I've answered this question twice. Instead of posting a generic question (at least partly generic) why don't you include the volume of NaOH used in the back titration. That way we can talk reality instead of do this/ do that.
July 11, 2015

Chemistry
I used a pKa2 for H3PO4 of 7.21. You should use the value in your text/notes. pH = pKa2 + log (base)/(acid) 6.4 = 7.21 + log b/a b/a = about 0.15 but you should do all of this more accurately. Then b = 0.15*a. That's equation 1. equation 2 is a + b = 0.2 M Solve these two ...
July 10, 2015

Orgnic chemistry
In this case inducing simply means that the highly EN group that gets close to the electronic cloud of the non-polar molecule distorts the cloud to make the molecule polar. That is, the EN group induces a polarity that is not there on its own.
July 10, 2015

Orgnic chemistry
Large molecules, such as I, can be induced to be polar when a highly EN element (such as F or Cl) come close. Smaller molecules don't do that because the electron field is so much closer to the nucleus. The large size of the I atom, however, makes the outer electrons less ...
July 10, 2015

org chem
No. Draw the Lewis structure for Cl-Cl and you will find 3 sets of unpaired electrons around each Cl atom but the Cl2 molecule is non-polar (mostly because there is no difference in electronegativity between one Cl atom and the other so the bond is not polar). For molecules in...
July 10, 2015

org chem
You look at two things. Are any of the bonds polar? If they are not the molecule will not be polar. Example H-H, Cl-Cl, etc. If there are polar bonds, go to #2. #2 is the symmetry. If the molecule is symmetrical in three dimensions it will not be polar. Most students don't...
July 10, 2015

chemistry
(P1V1/T1) = (P2V2/T2) Remember T must be in kelvin
July 9, 2015

itcs 1140
You have listed itcs 1140 as the subject. What subject is itcs 1140?
July 9, 2015

Chemistry
If A + B ==> C fast and C + D = E slow and E + F = fast step 1 is essentially instantaneous if it is fast and so is step 3. But step 3 can't take place any faster than step 2 so step 2 determines how fast the whole reaction is since anything past step 2 can't take ...
July 9, 2015

Chemistry
Thanks for letting me know.
July 9, 2015

Chemistry
For the other question I assumed it was a typo. I don't see an H2PO. There is no (H2PO)^2- ion in the chemical equation so there can't be one in the rate equation. Or I may have misinterpreted the subscripts and superscripts.
July 9, 2015

Chemistry
I would think something like this. "The hydroxide ion reacts with the H2PO2 ion according to the following equation: OH^- + H2PO2^- > HPO2^-2 + H2 What will be the change in the reaction rate if the H2PO2 ion concentration is increased. What will the effect if the ...
July 9, 2015

Chemistry
I think you have given a "qualitative" answer. I think the questions wants a "quantitative" answer. Look at the rate equation of rate = k[OH^-]^2*[(H2PO2)^2-] if OH is doubled then rate quadrupled because OH is squared. If H2PO2^2- is tripled, rate is ...
July 9, 2015

Science
Doubling NO will double the rate. If you mean rate will be tripled if O2 is tripled, yes, that's right.
July 9, 2015

Science
See your post above about OH^- and H2PO2^2-. Same scenario.
July 9, 2015

Science
Yes, I do these in one step. (-890.3 kJ/16.05g) x 6.4 = ? if -890.3 kJ/ was your calculated value for the combustion of CH4.
July 9, 2015

Science
Those H values you have are for kJ/mol and the dH you calculated for the CH4 combustion is in kJ/mol. Let's call that value you obtained x (it would have been nice for you to let us know the value you obtained), then convert 6.4 g CH4 to mols; i.e., 6.4/16 = ? Then x value...
July 9, 2015

Science
If that 24 is correct (and not 24.0) then you're right and I'm wrong and the number of significant figures is 2 so 1.3 is appropriate. But no matter which way you do the problem you should end up with the same answer if you use the same numbers for the molar masses.
July 9, 2015

Science
To follow the same pattern I followed above it would be +571.6 kJ for 36 g H2O so how much for 24 g? (571.6/36) x 24 = ? You've already divided the 571.6 by 2 so your step is ok as is EXCEPT you rounded and I don't know why? 24/18 = 1.33 mol.
July 9, 2015

Science
See your CH4 post. It's done the same way but make sure that's for 2 mols H2O.
July 9, 2015

science
Write and balance the equation. Convert 27 g Al to mols. mols = grams/atomic mass = ? Using the coefficients in the balanced equation, convert mols Al to mols H2. Then mols H2 x 22.4L/mol = L H2 at STP
July 9, 2015

Science
I obtained 11.7 for A. You probably used 14.008 for N. The only way I can get your answer to part B is to convert mols N2 as 11.8/14 but it should be 11.8/28 = mols N2 = 0.421. Then 0.421 x (3 mols Cl2/1 mol N2) = mols Cl2. mols Cl2 x 22.4 = about 28.3 L
July 9, 2015

Science
Balance the equation. N2 + 3Cl2 ==> 2NXl3 dH = 230 kJ If 28g N2 absorbs 230 kJ, then how much N2 is needed to absorb only 96.5? 28 x (96.5/230) = ? Convert g N2 from part a to mols. mol grams/molar mass = ? Use the coefficients in the balanced equation to convert mols N2 to...
July 9, 2015

oops--Chemistry
Yes, n is the number of mols. I goofed when I wrote dS when I meant dH. S is entropy, H is enthalpy.
July 9, 2015

Chemistry
dSrxn = (n*dSproducts) - (n*dSreactants)
July 9, 2015

Chemistry
If Ca metal loses 2e it becomes Ca^2+.
July 9, 2015

science
https://uk.answers.yahoo.com/question/index?qid=20130104055141AAQhFkb
July 9, 2015

chemistry
a = acid b = base pH = pKa + log (b)/(a) 7.8 = 8.1 + log (b/a) Solve for b/a. This is equation 1 and is the answer for part(a) equation 2 is a + b = 0.2 Solve these two equations simultaneously to obtain a and b at the beginning. This gives the answer to part (b). Can you take...
July 9, 2015

Chemistry
c = freq x wavelength. c = 3E8 m/s freq is given. Solve fopr wavelength.
July 8, 2015

Chemistry
It looks ok except for the 0.059. 10.08/183.59 = 0.0549 mols
July 8, 2015

Chemistry
https://en.wikipedia.org/wiki/Haber_process
July 8, 2015

Chemistry
See your other post.
July 8, 2015

chemistry
NH3 + H2O ==> NH4^+ + OH^- You know Kb and initial NH3 (6.0M), set up Kb expression and solve for OH^-. Then Qsp = (Mn^2+)(OH^-)^2 Plug in values for Mn^2+ and OH^- and compare Qsp with Ksp. Post your work if you need further assistance and explain exactly what you don'...
July 8, 2015

chemistry
How much do you want to prepare? 100 mL? Then mL1*%1 = mL2*%2 50*x = 100*20 Solve for x.
July 8, 2015

Chemistry
Use PV = nRT n = grams Ar/molar mass Ar R = 0.08206 L*atm/mol*K
July 8, 2015

Chemistry
I think the question is getting at the assumptions of the KMT. The gas molecules are points and occupy no volume (liquids and solids don't do that); there is no attractions between gas molecules (not true for liquids or solids), etc.
July 8, 2015

chem
What's the density of this 100 mL of SOLUTION? I don't know and can't answer the question without it. 5% w/w means 5 g AgNO3 in 100 g solution. IF you assume the density of this 100 mL is 1.00 g/mL, then the 100 mL will have a mass of 100 g. So you would need 5 g ...
July 8, 2015

Chem.
The mols HCl remaining in the flask after the tablet has been neutralized is just M NaOH x L NaOH = mols NaOH = mols HCl because that part of the reaction is HCl + NaOH ==> NaCl + H2O
July 7, 2015

Chem.
I'm not sure I understand the question. AFTER back titration you have no HCl remaining. The amount of HCl remaining after the reaction (probably with an antacid tablet) is determined by back titrating the remaining HCl with NaOH. mols NaOH used in the back titration is M x...
July 7, 2015

Chemistry
Note that I would capitalize the word Roman.
July 7, 2015

Chemistry
Yes.
July 7, 2015

Chemistry
I don't think so. You have explained how to name anions; the problem asks for cations. CuSO4 is copper(II) sulfate. FeCl2 is iron(II) chloride. FeCl3 is iron(III) chloride.
July 7, 2015

org chem
You look at the electronegativity. More EN makes more polar.
July 7, 2015

org chem
I'm not sure what you mean by "higher rate" of inductive effect. F > Cl > Br > I Also it depends upon how far apart the F,Cl, Br atoms are from the group affected. Here is a site where you can read more. https://en.wikipedia.org/wiki/Inductive_effect
July 7, 2015

chemistry
If you construct a diagram of a fcc crystal, the atoms touch along the diagonal but they don't touch along the edges. So one edge is 508, the other edge is 508 and the diagonal is sin 45o = 508/x x = length of the diagonal. It will be 4r in length. So radius A + 2*radius B...
July 7, 2015

Chemistry
2Mg + O2 ==> 2MgO
July 7, 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 which is the only unknown.
July 7, 2015

science
q1 = heat needed to raise T from 80 C to 100 C. q = mass H2O x specific heat H2O x (Tfinal-Tinitial) q2 = heat needed to vaporize H2O at 100 to steam at 100. q2 = mass H2O x heat vaporization. Note: I don't agree with those numbers you have for specific heat H2O or heat ...
July 7, 2015

chemistry
To fill the balloon you can do one of three. Zn + 2HNO3 ==> Zn(NO3)2 + H2 if you use dilute HNO3. H2 gas will fill the balloon. or 3Cu + 8HNO3 ==>3Cu(NO3)2 + 2NO + 4H2O NO gas will fill the balloon. HNO3 must be dilute. If HNO3 is concentrated you get Cu + 4HNO3 ==> ...
July 7, 2015

Chemistry
NH4^+ is the ammonium ion; ClO^- is the hypochlorite ion. The compound is NH4ClO because each has a valence of 1. (NH4)2SO4 is the correct formula for ammonium sulfate.
July 6, 2015

Chemistry
You omitted the charges. Should be K^+ and ClO^- and form KClO. However, the question asks for a polyatomic cation and K^+ is not polyatomic. NH4^+ would be an example of a polyatomic cation. For anions I would have thought sulfate, SO4^2-, would have come to mind faster than ...
July 6, 2015

Chemistry
I don't know from your description what the set up is.
July 6, 2015

Chemistry
I think your wording, although not exactly incorrect, implies that the term formula unit is a "fix" for a problem that doesn't exist and that isn't quite true. It is a "fix" for a problem that does exist. The idea is "don't call it a molar ...
July 6, 2015

Chemistry
Formula unit usually is used in connection with the "molar mass" of the compound. Some profs don't like to use the molar mass term because in some compounds, especially ionic compounds, the term mol is misleading. For example, we know that the substance CO2 ...
July 6, 2015

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