Wednesday
July 1, 2015

Posts by DrBob222


Total # Posts: 49,375

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

Science Help. Thank You! (:
You must dig through this but the information is there. https://en.wikipedia.org/wiki/Energy_use_in_California
June 15, 2015

chemistry
This is a limiting reagent (LR) problem since amounts are given for BOTH reactants. BaCl2 + Na2SO4 ==> BaSO4 + 2NaCl mols BaCl2 = M x L = ? mols Na2SO4 = M x L = ? Since this is a 1:1 reaction, the LR is the one with the smaller mols. That many mols BaSO4 will be formed. ...
June 15, 2015

chemistry
%yield = (actual/theoretical)*100 = ?
June 15, 2015

chemistry
1 pair 2 non-polar 3 polar 4 solubility but that isn't one of the choices but melting point fits also 5 water 6 electronegativity
June 15, 2015

chemistry
density H2O = mass x volume. 1.00 g/mL = mass x 175 mL mass 175 mL = 175 grams. mols in 175 g = 175/molar mass H2O = ? no molecules = ? mols x 6.02E23 = ? no molecules ethanol = same as H2O as ?. mols ethanol = #molecules/6.02E23 = ? grams ethanol = mols ethanol x molar mass ...
June 15, 2015

chemistry
6CO2(g) + 6H2O(l) + energy ==> C6H12O6(s) + 6O2(g) H2O may also be as a gas; i.e., in the vapor state. The produce may be as (aq) as is dissolved in the fluid of of the leaf.
June 15, 2015

Science 207
How would you like for us to help you with this assignment?
June 14, 2015

Chem
I might argue with you that Na2CO3 does not decompose on heating but for this problem we will assume that is true. 2NaHCO3 ==> Na2CO3 + H2O + CO2 I don't see how to do with other than two simultaneous equations. Let X = g NaHCO3 and Y = g Na2CO3 ----------------- eqn 1 ...
June 14, 2015

science chemistry
Take a 100 g sample which gives you 41.38g C 18.39g O 32.18g N 8.05g H Convert to mols. 41.38/12 = approx 3.5 18.39/16 = approx 1.15 etc. Then find the ratio of the atoms to each other with the smallest value being 1.00. The easy way to do that is to divide the smallest number...
June 14, 2015

science chemistry
P1V1 = P2V2
June 14, 2015

science chemistory
CaCO3 + 2HCl => CO2 + CaCl2 + H2O mols CaCl2 = grams/molar mass = 3.6/molar mass CaCl2 = ? Using the coefficients in the balanced equation, convert mols CaCl2 to mols CaCO3. If you want grams CaCO3, that is mols CaCO3 x molar mass CaCO3.
June 14, 2015

science chemistory
I recommend you find the + sign on your keyboard and learn to use it. CaCO3 + 2HCl => CO2 + CaCl2 + H2O You need to post all of the problem. 1. The molar mass of CaCl2 is 40.1+35.5+35.5 but "produced" makes no sense. 2. mols CaCO3 in what mass? 3. mass CaCO3 is ...
June 14, 2015

Chemistry
It looks ok to me. The negative sign is right but I think a consumption of -0.0018 is redundant. I believe the way to state it is a consumption of 0.0018 mol/s.
June 14, 2015

chemistry
mols KOH = M x L = ? mols aspirin = the same since both are monoprotic g aspirin = mols x molar mass %aspirin = (g aspirin/mass sample)*100 = ?
June 14, 2015

chemistry
What's your problem with using the diffusion rate law?
June 14, 2015

chemistry
Isn't this just like the others except one is HCl and the other acetic?
June 14, 2015

chemistry
same ol' same ol'. Look at your aspirin, acetic acid, etc titrations. I shall be happy to address specific questions you have about these but the method of working them is the same.
June 14, 2015

oops-typo--chemistry
This line mols NaOH - M x L = ? should read mols NaOH = M x L = ?
June 14, 2015

chemistry
You must know that 1 mol acetic acid = 1 mol NaOH mols NaOH - M x L = ? mols acetic acid = the same M acid = mols acid/L acid. Substitute and solve for M acid.
June 14, 2015

chemistry
You want delta T to be 12.5 C. delta T = Kf*m You know delta T and Kf, solve for molality (m). m = mols CH3OH/kg solvent. You know kg solvent and m, solve for mols CH3OH. Then mols CH3OH = grams/molar mass. YOu know molar mass and mols, solve for grams.
June 14, 2015

chemistry
mols urea = grams/molar mass = ? m urea = mols urea/kg solvent (kg solvent = 0.295) delta T = Kf*m. Solve for delta T Then subtract delta T from the initial freezing point.
June 14, 2015

Physical sciences
Do you have list from which to choose or are we to look through thousands of chemicals and try to pick the right one?
June 14, 2015

basic electronics
1/r1 + 1/r2 + 1/r3 = 1/r = 1/1000 r2 = 3r1 r2 = 2r3 Substitute and solve for r2 and evaluate for r1 and r3. Show your work if you get stuck.
June 14, 2015

Organic Chemistry
a is right. I believe b is sp2, trigonal planar. B has only 3 bonding electrons so can't be sp3. I don't know what c,d,f mean e is sp3 g is right I believe all of these are sp3 bonds but you should confirm that. i is sp3 j is sp2
June 14, 2015

Science
You're right.
June 13, 2015

chemistry
millimols NaCl = mL x M = 24.6 x 0.488 = estimated 12 mmols AgNO3 = estd 7.7 You need to redo these more accurately as well as all of the other numbers below. How advanced is this class? Basically, you have this but the final results depend upon just how complicated you want ...
June 13, 2015

Chemistry
Frankly, I am unfamiliar with CSH2 but here is a site that gives a good description of various IM forces. https://en.wikipedia.org/wiki/Intermolecular_force
June 13, 2015

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