Saturday
September 5, 2015

Posts by DrBob222


Total # Posts: 49,901

Chemistry
.........XY2 ==> X^2+ + 2Y^- I........solid...0.......0 C........solid...z.......2z E........solid...z.......2z Ksp = 2.2E-4 = (X^2+)(Y^-)^2 2.2E-4 = (z)(2z)^2 Solve for z.
June 24, 2015

Chemistry
You've done it in the question. Na^+ is the symbol for the sodium ion and SO4^2- is the symbol for the sulfate ion.
June 24, 2015

Chemistry
I don't see a question here.
June 24, 2015

chimistry
q = mass x heat fusion = ? Remember to change 97.0 g to mols.
June 24, 2015

Chemistry
The atomic number of P is 15 which means P has 15 protons; therefore, the number of electrons for a neutral P atom MUST be 15. m being 1 affects the energy level of one or more of the electrons (and of course the P atom) but it doesn't change the number of electrons from 15.
June 23, 2015

Science
http://www.chemteam.info/Redox/Redox-Rules.html
June 23, 2015

Chemistry
You made two errors. The rest is ok. You want grams CaCl2 and not Cl so omit Cl. That's mols needed = M x L = 2.00L x 3.5M = 7.00 mols. Then grams = mols x molar mass = 7.00 x 110.98 = about 777 g. How you obtained 5.55 grams I don't know. YOu must have punched the ...
June 23, 2015

Chemistry
I give up. It posted then. Sorry about all of this but I think I have all of your answers posted. Let me know if I omitted something.
June 23, 2015

Chemistry
(OH^-) is what I can't post.
June 23, 2015

Chemistry
I don't know why I couldn't post all of the answers with one post. 8. Convert OH^- to pH.
June 23, 2015

Chemistry
The last one is to convert OH^- to pH.
June 23, 2015

Chemistry
7. ........B^- + HOH ==> HB + OH^- I.......0.0167.............0....0 C..........-x..............x....x E.......0.0167-x...........x....x Kbase for B^- is (Kw/Ka for HB) = (x)(x)/(0.0167-x) Solve for x = (OH^-).
June 23, 2015

Chemistry
6. When the B^- reacts with H2O it is ............B^- + HOH ==> HB + OH^- so you are looking for OH^- which you let be x.
June 23, 2015

Chemistry
5. I don't know which K you are talking about. K for HB is given in the problem as 6.3E-5. I expect you are talking about the Kb for B^- (benzoate ion) and that is Kb benzoate = (Kw/Ka for HB) = ?
June 23, 2015

Chemistry
4. millimols HB = 0.3 volume NaOH = 6 mL total volume = 18 mL at equivalence point. If we call benzoic acid HB, then .........HB + NaOH ==> NaB + H2O I.......0.3.............0.....0 add...........0.3................ C.......-0.3..-0.3......0.3.....0.3 E........0.....0...
June 23, 2015

Chemistry
I have tried posting the answer but the site won't let me. I'll try posting them as separate problems. The first three are right.
June 23, 2015

pragati s.s.h.s.s
Power is not one of the basic seven SI units. Anything not one of the original seven can be obtained in terms of one or more of the seven basic units. Those are called "derived units".
June 23, 2015

physcial science
c = frequency x wavelength 344 m/s = 25000 Hz x w solve for wavelength in meters. Do the same for 30 Hz
June 23, 2015

chemistry
I did this for you yesterday. Go back and find that work. I can find it for you if you can't.
June 23, 2015

Chemistry
Here is a site you can read. I don't think 86 is the right answer either. I think closer to 0.39 (39%) https://en.wikipedia.org/wiki/Extent_of_reaction
June 23, 2015

chemistry
Convert 1.06 g Ni(OH)2 to g NaOH. That's 1.06 x (2*molar mass NaOH/molar mass Ni(OH)2) = ?. That's the g NaOH in excess. How many g NaOH was in the original? That must be g excess NaOH + g titrated by HCl. How much was titrated by HCl? That's L x M x molar mass ...
June 23, 2015

chemiestry
I did that for you yesterday.
June 23, 2015

chemistry
See your other post.
June 23, 2015

Chemistry
First find the molarity of the concentrated HNO3. 1.42 g/mL x 1000 mL x 0.0704 x (1 mol/63g) = ? M. Then use the dilution formula of mL1 x M1 = mL2 x M2 33.4 x ?M = 2000 mL x M2. Solve for M2.
June 23, 2015

college chemistry
8g NaOH = 8/40 = 0.2 mols 8g HCl = 8/36.5 = 0.22 mol So NaOH is the limiting reagent. q = mass x secific heat H2O x (Tfinal-Tinitial) q = (50+250) x 4.184 x (33.5-25) = ? q is delta H in J (convert to kJ) and that is all the post asks for. Usually these problems want kJ/mol
June 23, 2015

biology
I'm not a biologist and I can't help you with this; however, I would like to point out that BOOKS are written covering this information and you want someone to answer in that kind of detail. I don't think you will get any takers.
June 22, 2015

chemistry
Please rephrase the question. As posted it makes absolutely no sense. You've just jumbled the words.
June 22, 2015

chemistry
I haven't hear solidity used in connection with H2O before; are you trying to say density since density is 1 g/mL. mass H2O = volume x density = 18 mL x 1 g/mL = 18 grams. mols H2O = g/molar mass = 18/18 = 1 mol There are 6.02E23 molecules in 1 mol. There are 16 electrons ...
June 22, 2015

chememistry
(2*H + 1*O) = ? Plug in atomic mass H and atomic mass O and solve for ? That's approx 18.
June 22, 2015

Chem 30
Solubility is 30g/100g H2O at 20C; therefore, how much will 140 g hold? That's 30 x (140/100) = ? Subtract from 60 to find the amount that comes out of solution.
June 22, 2015

Organic Chemistry
That is my take on it.
June 22, 2015

Organic Chemistry
I would go with the bond dissociation energy. Here is a table. Distance, as you suggest, plays a part but so does the polarity of the bond. https://labs.chem.ucsb.edu/zakarian/armen/11---bonddissociationenergy.pdf
June 22, 2015

CHEM
What numbers did you get and how did you get them?
June 22, 2015

chemistry
You want 2 L of 0.50 M. How many mols is that? That's mols = M x L = ? Then mols = grams/molar mass. You know mols and molar mass, solve for grams.
June 21, 2015

Chemistry
millimols HF = mL x M = approx 375 mmols NaF = 1500 x 0.25 = 375 mmols NaOH added = 50 ........HF + OH^- ==> H2O + F^- I......375...0........0.....375 add..........50................ C.....-50...-50.......50.....50 E......325...0...............425 Substitute the E line into...
June 21, 2015

Chemistry
Isn't this the same question (different substance and different numbers but the same procedure) Damon did for you below with the Fe question?
June 21, 2015

Chemistry
If you know the definition is M = mols/L, then what is the problem. Substitute the numbers and out comes the M. By the way, if mL is 2,660 mL, then L = 2.660 L.
June 21, 2015

Chemistry
Damon answered this at your post below. You need to look to see if you have answers before posting again.
June 21, 2015

Chemistry
First, since the k2 is so small, ignore it. The pH will be determined by the dissociation of k2 only. ..........H2Se ==> H^+ + HSe^- I.........0.4......0......0 C..........-x......x......x E......0.4-x.......x......x Substitue the E line into k1 expression and solve for x...
June 21, 2015

science
Perhaps I've missed something but I don't see what all of that information about collisions and 92 nm has to do with the problem. Use PV = nRT, substitute the numbers in the problem and solve for T in kelvin.
June 21, 2015

Chemistry
Look up sodium hydrogen carbonate (or sodium bicarbonate). If you can get a Wikipedia site choose that and you can get the other information there. There is no way to get the mols for the recipe since you didn't give the recipe.
June 20, 2015

Dilsuknagar public school chemistry
Zn + 2HCl ==> H2 + ZnCl2 mols Zn = grams/atomic mass = ? Use the coefficients in the balanced equation to convert mols Zn to mols H2. volume H2 = mols H2 x 22.4 L/mol = ? mass H2 = mols H2 x molar mass H2 = ? # molecules H2 = mols H2 x 6.02E23 = ?
June 20, 2015

Chemistry
I agree with A
June 20, 2015

chemistry
q = mass x specific heat x delta T. q = 150 x 4.18 x 8 = ? J which is delta H for the reaction. Most of these problems want delta H/mol or delta H/g but this post asks for neither.
June 20, 2015

chemistry
You need either the solubility of N2 or Henry's Law constant. Do you have either. Yo can look them up if neither is listed in the problem.
June 20, 2015

Science
See your other post.
June 19, 2015

Science
I don't understand the question. Please clarify.
June 19, 2015

chjem
I am not an organic chemist but my best educated guess is that you don't want the alcohol to form; i.e., the water present in wet HCl would hydrate the double bond forming an alcohol.
June 19, 2015

nyenyezi chrisian academy
ZnO + 2HCl ==> ZnCl2 + H2O 1. Convert 19.2 tones ZnO to mols. mols = grams/molar mass which means you must convert tones to grams first. 2. Using the coefficients in the balanced equation, convert mols ZnO to mols ZnCl2. 3. Now convert mols ZnCl2 to grams. g = mols x molar ...
June 19, 2015

PreChem
What is your problem in doing this? The first one is a combustion reaction (also a redox reaction).
June 18, 2015

Chemistry
ZnCO3 + 2HCl ==> H2O + CO2 + ZnCl2 CuCO3 works the same way. Look up "greenhouse effect" on google to obtain information about CO2 and it's effect on the environment.
June 18, 2015

Chemistry
See your other post.
June 18, 2015

UNIBEN Demonstration secondary school, benin city,Nigeria
Example. mols substance 1 = 2 mols substance 2 = 3 mol fraction 1 = 2/5 mol fraction 2 = 3/5
June 18, 2015

Chrmistry
What's the problem here? One product is given; the other is what's left over. K3PO4(aq) + MgCl2(aq) ==> Mg3(PO4)2(s) + KCl(aq) This is a double replacement reaction. Can you balance it from here?
June 18, 2015

B. My gange girls sen sec school (science)
In series the R is 24 ohms (R1 + R2). In parallel the R is 12 ohms(1/R1 + 1/R2 = 1/R). E = IR or I = E/R. You know E and R, solve for I.
June 18, 2015

Chemisrty
This is pretty basic stuff to be lost. grams = mols x molar mass is all there is to it.
June 17, 2015

chemistry
https://answers.yahoo.com/question/index?qid=20120508005033AAMaEvk
June 17, 2015

Chemistry
You want how many mols? That's M x L = mols KI. How many grams is that? That's mols = grams/molar mass. You have molar mass and mols, calculate grams. Place that many grams KI in a 500 mL volumetric flask, add a little DI water, swirl until all KI is dissolved, add DI ...
June 17, 2015

Chemistry
mols KI = M x L = ? Use the coefficients in the balanced equation to convert mols KI to mols PbI2. Now convert mols PbI2 to grams. g = mols x molar mass = ?
June 17, 2015

physical science chemistry
What's the concn of the KOH? mols HCl = M x L mols KOH = mols HCl M KOH = mols KOH/L KOH used.
June 17, 2015

chemistry
Interesting but you gave no equation. Here is what I suspect. .........CO + H2O ==> CO2 + H2 I........5.....2.......0.....0 C........-x...-x.......x.....x E.......5-x...2-x......x.....x The problem tells you that 2-x = 0.5. Evaluate the terms, substitute into Kc expression ...
June 17, 2015

Chemistry
4Al + 3O2 ==> 2Al2O3 1.58 mols O atoms = 1.58/2 = 0.79 mols O2 molecules. Use the coefficients to change from 0.79 mols O2 to mols Al. That's 0.79 x (4 mols Al/3 mols O2) = 0.79 x 4/3 = ?
June 17, 2015

chemistry
This is a limiting reagent (LR) problem and you know that because amounts are listed for both reactants. 2H2 + O2 --> 2H2O mols H2 = grams/molar mass = ? mols O2 = grams/molar mass = ? Use the coefficients in the balanced equation, to convert mols H2 to mols H2O. Do the ...
June 17, 2015

chemistry
C + O2 ==> CO2 mols CO2 = grams/molar mass = ? Use the coefficients in the balanced equation to convert mols CO2 to mols C. Now convert mols C to grams. g = mols x molar mass = ?
June 17, 2015

chemistry
I assume you are asking which contains the highest number of significant figures. That is a contains 1 b contains 6 c contains 3 e contains 3
June 17, 2015

chemistry
mols H2O = g/molar mass = ? Then use the fact that 1 mol contains 6.02E23 molecules.
June 17, 2015

Carmel
x = what the card holds 1/4 x = what it has now. 1/4 x + 375 = 2/3 x Solve for x = what the card hold. 2/3 x is what is on it
June 16, 2015

Chemistry
You're a good chemist if you can make Mn^2+ go to Mg^2+. :-). I think you are right. Mn^2+ can't be reduced preferentially. I vote for H2 gas at the cathode.
June 16, 2015

Chemistry
That answer I gave you are for gases only. You count the mols. For a you have 2 mols NH3 on the left and 4 mols on the right so an increase in mols means increase in entropy. b. You have 3 mols gas on left and zero on the right.
June 16, 2015

Chemistry
For the entropy, larger number of moles means more entropy. That will answer both a and b. I don't understand the rest of the question because of the funny symbols.
June 16, 2015

college chemistry
mols H2SO4 = grams/molar mass = ? M H2SO4 = mols H2SO4/L solution.
June 16, 2015

chemistry
It's a case of plugging into the HH equation and solve. Convert Ka to pKa.
June 16, 2015

chemistr
How many equivalents do you want? That's N x L = ? Then equivalents = grams/equivalent weight. The equivalent weight of HNO3 is the same as the molar mass.
June 16, 2015

Chemistry
mass % = (mass solute/mass solution)*100 = ? mass = volume x density mass solution = 3810 g x 0.997 g/mL = ? grams solution % = (158/? g solution)*100 = ?
June 16, 2015

Chemistry.
Cu+FeCl3--->CuCl3 + Fe Double replacement This reaction will not occur. First, if it did occur it would be a single replacement (you've replaced only one metal) and second, to occur the single element must be ABOVE the ion in the activity series. Cu is below Fe; ...
June 16, 2015

Science Help. Thank You! (:
We usually don't give answers with no work. If you don't want to read you don't want to work. I'll be glad to provide a link but you must read it to get the answer
June 16, 2015

Chemistry
What is to solve? 2. is 1.2v and that site said so. 4. is 1.2v and that site all but said so. The words were something like that the cell continued to discharge produce maximum voltage until it was all but completely discharged. For which is the anode and cathode, find those ...
June 16, 2015

Chemistry
I believe all of these questions are answered here. https://en.wikipedia.org/wiki/Nickel%E2%80%93cadmium_battery Scroll down to the chemical part to get the equations and discussion of charge vs discharge.
June 16, 2015

chemistry
#eq = grams/equivalent weight. You have grams in the problem. equivalent weight Mg(OH)2 = molar mass/2.
June 16, 2015

chemistry
Ba(OH)2 + 2HNO3 ==> 2H2O + Ba(NO3)2 mols Ba(OH)2 = M x L = ? Using the coefficients in the balanced equation convert mols Ba(OH)2 to mols HNO3. Then M HNO3 = mols HNO3/L HNO3. You have M and mols, solve for L. Convert to mL if desired.
June 16, 2015

Electrolysis
What solvent is in the electrolytic cell?
June 16, 2015

chemistry
How would like us to help you with this assignment?
June 16, 2015

chemistry
Sorry, I may have misled you due to a typo I didn't put in. That equilibrium should have looked like this; .......Al(OH)3 ==> Al^3+ + 3OH^- I.......solid......0.........0 C.......solid......x.........3x E.......solid......x.........3x 3.7E-5 = (x)(3x)^3 3.7E-5 = 27x^4 x...
June 16, 2015

chemistry
This won't be the correct answer to the problem (but it is the correct answer to the problem that is posted). .......Al(OH)3 ==> Al^3+ + 3OH^- I.......solid......0.........0 C.......solid......x.........x E.......solid......x.........x Substitute the E line into Ksp and...
June 16, 2015

chemistry
I don't think Ksp is correct. Can't be that large. Also, how advanced is this class?
June 16, 2015

chemistry
........Mg(OH)2 ==> Mg^2+ + 2OH^- Ksp = (Mg^2+)(OH^-)^2 Plug in 0.01 M for (Mg^2+) and solve for OH-, then convert OH^- to pH.
June 16, 2015

chemistry
I would do this. For a ppt to form you know Ksp must be exceeded; therefore, ..........CaSO4(s) ==> Ca^2+ + SO4^2- E.........solid........x........x You also know that adding 0.01M H2SO4 will increase the solubility of CaSO4 due to the reaction of SO4^2- + H^+ ==> HSO4...
June 16, 2015

Chemistry
CaCO3 ==> Ca^2+ + CO3^2- Ksp = (Ca^2+)(CO3^2-) H2CO3 ==> H^+ + HCO3^- k1 = .... HCO3^- ==> H^+ + CO3^3- k2 = .... pH = 4.20; (H^+) = 6.31E-5 Solubility = (Ca^2+) = S S = (CO3^2-)+(HCO3^-)+(H2CO3) Find (CO3^2-) in terms of S. k2 = (H^+)(CO3^2-)/(HCO3^-) Plug in k2 and ...
June 16, 2015

chemistry
At STP is 22.414 L.
June 16, 2015

Chemistry
For 4, what is your problem? What have you done and what don't you understand. For 5, what is your problem? What have you done? Where are you stuck? What do you not understand.? Still can't figure it out doesn't help me know what's wrong.
June 16, 2015

Chemistry
So you have 1,2,3. 4. C4H4O4 which since it is diprotic we can write H2M. H2M + 2KOH ==> 2H2O + K2M mols KOH = M x L = ? mols H2M = 1/2 that from the coefficients M H2M = mols H2M/L H2M. That give you the M of the solution but I don't understand why this information is...
June 16, 2015

Chemistry
This is a workaholic problem. 1. Determine empirical formula. 2. Determine molar mass 3. Determine molecular formula. 4. Determine the molarity of the maleic acid in the titration experiment. 5. Determine Ka1. And you need help with which one. Show your work for what you have ...
June 16, 2015

Chemistry
pKa = 4.77 is pK2; therefore, I assume you are asking for the change in pH of that solution, not necessarily that of citric acid. Use the HH equation.
June 16, 2015

analytical chemistry
Help me a little by telling me what you don't understand. Calculate millimols HAc and mmols NaAc and plug into the HH equation and solve for pH. Then use an ICE chart, add the mmoles HCl and complete the E line of the ICE table. Then plug into the HH equation again and ...
June 16, 2015

analytical chemistry
I'm confused. You have titrated NaHCO3 but you give the molar mass of Na2CO3. I will assume the 0.4617 g sample did not contain Na2CO3 (or any other carbonate) mols HCl = M x L = ? mols HCO3^- = mols HCl since the ratio in the equation is 1:1 Convert mols HCO3^- to grams ...
June 16, 2015

Organic Chemistry
https://en.wikipedia.org/wiki/Cis%E2%80%93trans_isomerism
June 15, 2015

Chemisty
I'll bet if you made that N2O4 ==> 2NO3^- you could balance the whole thing. What about it?
June 15, 2015

Chemistry
That other post is above and not below but it adds no other useful information.
June 15, 2015

Chemistry
See your other post below. If you use acid solution AND use N2O4 ==> 2NO3^- as the starting point for the second equation I'll be you can balance the whole thing. Try it and let me know but especially tell me what you don't understand if that doesn't work for you.
June 15, 2015

chemistry
(V1/T1) = (V2/T2)
June 15, 2015

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