Wednesday
June 29, 2016

Posts by DrBob222

Total # Posts: 52,597

chemistry
In your book the reaction between iron and oxalic acid to produce iron(II) oxalate. Then they go through a decomposition of iron(II) oxalate to form iron(II) oxide. This is a two-step synthesis. Bob Pursley gave you the direct one-step process which is far easier to do.
February 4, 2016

Gen Chem
This a multistep problem involving simultaneous equations. pi = i*M*R*T. I is the van't Hoff factor. Substitute and solve for M = molarity. Then you have two equations. Let X = grams NaCl and Y = grams sucrose = SU equation 1 is X +Y = 10.2 Then mols NaCl + mols SU = total...
February 4, 2016

Chemistry- Dr. Bob222
I obtained 109.22 but I think the 37.4 kJ number allows only 3 sig figures.
February 4, 2016

Chemistry
2F2(g)+2H2O(l)= 4HF(aq) + O2(g)
February 4, 2016

Chemistry
See your other post.
February 4, 2016

Chemistry
If it is heated enough to boil off some of the water it will become more concentrated in the acid and that will lower the pH. If it is heated slightly and you use a regular pH meter, most meters have an adjustment to correct for that so the pH should be correct as measured.
February 4, 2016

CHEM HELP PLEASE
https://www.youtube.com/watch?v=riMzriytw40
February 3, 2016

chemistry
Like dissolves like. That is, polar solvents dissolve polar solutes but not non-polar solutes and non-polar solvents dissolve non-polar solutes.
February 3, 2016

Chemistry
delta T = i*Kf*m i = van't Hoff factor, which for KNO3 is 2. So -0.744. b. Have you had anything about the Debye-Huckel theory/law. That says the 0.2 m is not quite 0.2 and as the concn increases there is more attraction between solvent/solute molecules. The net result is ...
February 3, 2016

Chemistry
2AgNO3 + Cu ==> Ag + Cu(NO3)2 Cu metal is more easily oxidized than silver metal so the Cu metal is oxidized and the Ag ion is reduced to silver metal.
February 3, 2016

chem 12
I think you are using some of the numbers incorrectly. .........N2 + O2 ==> N2O4 I......0.04..0.04.....0 C.......-x...-2x......+x E...0.04-x...0.04-2x...+x The problem states that the N2 consumed (that's x) is 0.0059 so the new (N2)is 0.04-0.0059 = ? New (O2) is 0.04-[2...
February 3, 2016

Chemistry
ppmv = (2E-8/100)*10^6 = ?
February 3, 2016

Chemistry
Sc 1s2 2s2 2p6 3s2 3p6 3d1 4s2 Basically the 3d and 4s levels are so close in energy for Sc that energy necessary to remove 4s2 and 3d1 are about the same so you see only +3 oxidation state.
February 3, 2016

Chemistry
There may be a number of reasons. One is that the electrons in Mn and O are shared and not transferred but this may not be the answer you are looking for.
February 3, 2016

Chemistry
Mn has 25+ and 23- for +2 net. Fe has 26+ and 24- for +2 net. Therefore, Fe^2+ has a higher + charge pulling on those outside electrons.
February 3, 2016

Chemistry
The 41 drops is correct but not the 14. That's for water. You want HIO3 so it is 0.010 x (6/41) = ?
February 2, 2016

Chemistry
The other halogen (I,Br, Cl) are large enough to accommodate 5 or 7 F atoms and have enough space for the extra pair of electrons (there are more than 8 around the B atom). However, note that IBr5 and BrCl5 (and others) are not "invariably" F.
February 2, 2016

chemistry
I would do a melting point.
February 2, 2016

Chemistry
That looks good to me but you have too many significant figures if you posted the problem correctly. 7.5 L allows only two places and I would round to 22 g.
February 2, 2016

Chemistry
(HI) = 16.7/10 = 1.67 M .....H2 + I2 ==> 2HI I.....0....0......1.67 C.....x....x......-2x E.....x....x.....1.67-2x Plug the E line into the Kc expression and solve for x
February 2, 2016

Chemistry
Use the Clausius-Clapeyron equation. You can use the "other" p/t numbers as 273 K at 760 torr. Remember to use the correct value for R.
February 2, 2016

Chemistry
Mike, what is your trouble with this?
February 1, 2016

chemistry
I would like to clarify Steve's answer a little. Since the question is so detailed about the phases I suspect the author of the question wants you to include the phases like this. HCl(aq) + NaHCO3(s) --> H2O(l) + NaCl(aq) + CO2(g)
February 1, 2016

chem
q = mass x specific heat x (Tfinal-Tinitial).
February 1, 2016

chemistry
v1/t1 = v2/t2
February 1, 2016

chemistry
This is a limiting reagent (LR) problem and you know that because amounts are given for BOTH reactants. 2C2H6 + 7O2 ==> 4CO2 + 6H2O mols C2H6 = grams/molar mass = ? mols O2 = grams/molar mass = ? Using the coefficients in the balanced equation, convert mols ethane to mols ...
January 31, 2016

Chemistry
It would help if you gave an example of what you're asking.
January 31, 2016

chem
I didn't check the math but the numbers and substitution are correct.
January 31, 2016

chemistry
AgNO3 + NaCl ==> AgCl + NaNO3. You quote all of those numbers BUT ask only for the equation. Two observations. 1.This is a limiting reagent problem if you want to do the math and determine the amount of AgCl formed. 2. I call that silver nitrate and sodium nitrate. In my ...
January 31, 2016

Chemistry
1 no. PV = nRT and solve for n = number of mols. Then n x 6.022E23 = number He atoms. Same at both temperatures. 2. density = P*molar mass/RT gives density in g/L. Convert to g/L.
January 31, 2016

Chemistry
1. p1v1 = p2v2 p1= 5 atm v1 = 1 L p2 = ? v2 = 11 Solve for p2 = partial pressure Ar in the combined system. Do the same and calculate pN2. Ptotal = pN2 + pAr pN2 = XN2*Ptotal. Substitute and solve for XN2. pAr = XAr*Ptotal. Solve for XAr. 3. If XAr = 0.5, then XN2 must be 0.5 ...
January 31, 2016

Chemistry
I THINK your problem is that the value of 0.87 is two significant figures (s.f.) but your answer is 5 s.f. and that isn't kosher. Try rounding your answer to 2 s.f. (1.8) and see if that works.
January 28, 2016

chemistry
29.568 g = mass bkr and alcohol. -24.568 g = mass empty bkr ----------- 5.000 g = mass alcohol Then volume = mass/density. Substitute and solve for volume in cc.
January 27, 2016

Chemistry
I don't know how you obtained that answer but the unit is %. The molar mass of Al2(SO4)3.18H2O is 666.429 and 18 mols H2O = 324.275 so %H2O = about (324/666)*100 = ?%. You can do it more accurately.
January 27, 2016

chemistry
This is a lot of writing. I shall be happy to critique your thoughts. If you don't know the process in each, look on google, read your text/notes, ask here and explain what you don't understand.
January 27, 2016

chem 101
q = mass H2O x specific heat H2O x (Tfinal-Tinitial)
January 27, 2016

Chem
Use PV = nRT P = unknown to be calculated. V = 500 mL but convert to L. n = grams He/molar mass He. R = 0.08206 L*atm/mol*K T = 77 K. Note this calculation does not involve H2. Dalton's Law tells us that EACH gas exerts its own partial pressure regardless of other gases ...
January 27, 2016

Chemistry
I think this is just what you're looking for. BCC is 2, FCC us 4, simple cubic is 1. http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch13/unitcell.php#determ
January 27, 2016

Chemistry
More than likely it is F2.
January 27, 2016

Chemistry
2H2 + O2 --> 2H2O mols H2O = grams/molar mass = ? Using the coefficients in the balanced equation, convert mols H2O to mols O2. If you want amount O2 in grams, then g O2 = mols O2 x molar mass O2.
January 27, 2016

Chemistry 102
M Fe^3+ = 1.11E-3 x (16/26) = ? and lets calls this a. M SCN^- = 1.11E-3 x (10/26) = ? and let's call this b. ......Fe^3+ + CN^- --> FeCNS^2+ I.....a........b.........0 C....-x.......-x.........x E....a-x.......b-x.......x Substitute the E line into the Kc expression ...
January 27, 2016

Chemistry
Use PV = nRT You know P (1 atm), v(55 cm but change that to L), n (solve for this), R (0.08206 L*atm/mol*K), T (20 C but change that to kelvin). n = number of mols. grams CO2 = mols x molar mass CO2 T(kelvin) = celsius T + 273
January 27, 2016

Chem
mols glucose = 1.50 mols water = 3.50 total mols = 1.50 + 3.50 = ? X(mol fraction) H2O = mols water/total mols. Psolution = Xsolvent*Po solvent
January 27, 2016

Chemistry
m is molality and M is molarity; however, I understand Osm is the osmolarity of the solution. I will answer on that assumption. MgCl2 has a van't Hoff factor of 3; i.e., MgCl2 ionizes in solution to three particles. How many OSm do you want? That's 0.4 x 2/3 = ? grams...
January 27, 2016

Chemistry 101
mass = volume x density
January 27, 2016

Chemistry 101
No. Yes, mass = volume x density so volume = mass/density = 2/0.785 = ?
January 27, 2016

Chemistry
2H2 + O2 ==> 2H2O + heat So 4.5 g gives 72 kJ, heat for the reaction above is -72 kJ x 36 g/4.5 g = -576 kJ. That's for 2 mols so for 1 mole is it -576/2 = ?
January 27, 2016

Chemistry
There are 5 mols C in each mol of C5H12; therefore, in 10.5 mols C5H12 there must be 5*10.5 = ? mols C.
January 27, 2016

Chemistry
Please post ALL of problem.
January 27, 2016

Chemistry
All of those look ok to me. Thanks for showing your work.
January 26, 2016

Chemistry
Yes.
January 26, 2016

Chemistry
The problem is that you don't have all of the reactants and products shown. You need H2SO4 (or another acid) on the left and H2O and K2SO4 (or the salt of the another acid used) on the right.
January 26, 2016

Chemistry
What k value in what? What are you studying?
January 26, 2016

Chemistry
Actually you need to repost the question. Did you make a typo? Is that NH3? And when one normally talks about a 0.2M buffer one means the TOTAL is 0.2 but you have 0.2 for each of two materials. I assume that is 0.2M NH3 and 0.2M NH4NO3.
January 26, 2016

chemistry
p1v1 = p2v2
January 26, 2016

chemistry
v1/t1 = v2/t2
January 26, 2016

Chemistry
https://www.google.com/search?q=example+chiral+centers+but+achiral+structures&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwjp4LbF68bKAhVpuoMKHUjQBioQsAQISA&biw=996&bih=624
January 26, 2016

Chemistry
http://chemwiki.ucdavis.edu/Physical_Chemistry/Nuclear_Chemistry/Nuclear_Stability_and_Magic_Numbers
January 25, 2016

Chemistry
So you need to change miles to km and gallons to liters. Can you do that? If not, exactly what about the process confuses you?
January 25, 2016

AP Chem
See if this helps. Google sp hybridization and there are several sites to read. https://www.khanacademy.org/science/chemistry/chemical-bonds/copy-of-covalent-bonds/v/sp-hybridization-jay-final
January 25, 2016

Chemistry
silver(I) nitrate -AgNO3 correct ok iron(III) oxide - Fe2O3 correct ok sodium bicarbonate - Na2HCO3 - incorrect. OK. NaHCO3 is the correct formula. The newer name is sodium hydrogen carbonate calcium phosphate - CaPO3 in correct. No. The correct formula is Ca3(PO4)2 rubidium ...
January 25, 2016

chemistry
24 mols Fe2O3 x (2 mols Fe/1 mol Fe2O3) = not about but exactly 24
January 25, 2016

Chemistry
C4H10 + 9mO2 ==> 4CO2 + 10H2O mols C4H10 = grams/molar mass = ? Using the coefficients in the balanced equation, convert mols C4H10 to mols CO2 Now convert mols CO2 to g CO2 by grams CO2 = mols CO2 x molar mass CO2
January 25, 2016

chemistry
7.2 x 5 36
January 25, 2016

chemistry
C3H8 + 5O2 --> 3CO2 + 4H2O 7.20 mols C3H8 x (5 mols O2/1 mol C3H8) = 7.20 x 5/1 = ?
January 25, 2016

Chemistry
Take a 100 g sample which gives you 87.8g C 12.2 g H Convert to mols = g/atomic mass 87.8/12 = approx 7.3 12.2/1 = 12.2 Determine the ratio of the two elements to each other with the lowest number being no less than 1.00. The easy to do that is to divide both numbers by the ...
January 25, 2016

chemistry
Who says it's physics and not chemistry. It's both but chemistry uses this all of the time. In fact my Ph. D. dissertation used radioactive Co, Mo, Cu, In, and Zn to prove what I had to prove. ln(No/N) = kt No = 15 N = 3 k = ? t = 3 days Solve for k. Then use ln(No/N...
January 25, 2016

chemistry
I can't make sense of your post. You need to proof these things before posting. If you want the new volume, use p1v1 = p2v2
January 25, 2016

chemistry
q1 = heat to move T of solid ice from -3 to zero. q1 = mass ice x specific heat ice x (Tfinal-Tinitial). Tf is 0; Ti is -3 q2 = heat needed to convert ice at zero C to liquid at zero C. q2 = mass ice x heat fusion ice. q3 = heat needed to change T liquid H2O from zero C. to 25...
January 25, 2016

Chemistry
C3H8 + 5O2 ==> 3CO2 + 4H2O 10 L O2 x (3 mols CO2/5 mols O2) = 10 L x 3/5 = ?
January 25, 2016

Chemistry 101
If you want it in pounds/cc it is 0.0750/volume and volume is 31.3-22.4; otherwise convert pounds to grams. There are 453.59 grams in one pound.
January 25, 2016

Chemistry 101
See your previous posts. All of these are more or less alike.
January 25, 2016

Chemistry 101
Convert in, ft to cm. volume = L x W x H mass = volume x density
January 25, 2016

Chemistry 101
volume sphere is V = (4/3)*pi*r^3 density = mass/volume
January 25, 2016

science
Since the van't Hoff factor is higher for CaCl2 it will have the higher b.p. for the same molality.
January 25, 2016

chemistry
PV = nRT P = 10 V = 40 n = 2,500/32 = ? R = 0.08206 T = ? Then PV = nRT P = 15 V = 40 n = ? R = see above T = from above. Solve for n, then n = grams/molar mass. You know n and molar mass, solve for grams O2 needed.
January 25, 2016

chemistry
0.208 x 28 = ? 0.258 x 32 = ? 0.284 x 44 = ? 0.25 x 2 = ? Avg molecular weight is sum of the above.
January 25, 2016

chem
q = mass Al x specific heat x (Tfinal-Tinitial)
January 25, 2016

Chemistry
C2H2 + H2 ==> C2H4 + 6.3 kJ I don't know how you obtained that answer for a. Isn't be just 6.3 kJ? As for the T change, the problem states it is STP at the beginning and is maintained at STP. As for your calculation for b, how did the specific heat H2O get in there.?
January 25, 2016

AP Chem
1. http://www.chemguide.co.uk/physical/phaseeqia/nonideal.html 2. C = KpP Plug in K and P and solve for C in M. Then M = mols/L and solve for mols.l Then mols = g/molar mass and solve for grams. 3. Ideal values. a = 2 b = 3 c 1 d = 2. d is the only one HIGHER than the ideal.
January 24, 2016

chemistry
PV = nRT and solvle for n, then n = grams/molar mass = ?
January 24, 2016

chemistry
see Steve's answer below.
January 24, 2016

Chemistry
...CH3COOH + C2H5OH ==> CH3COOC2H5 I....2M.......1M..........0 C....-x.......-x..........x E...2-x.......1-x.........x Substitute the E line into the Keq expression and solve for x = the ethanoate.
January 24, 2016

for solubility
How much solution do you need? 500 mL? Some other number? Use the appropriate number. 500 x 0.1 = mL x 0.123. Solve for mL of the 0.123 N NaOH and add water to make 500 mL.
January 24, 2016

Chemistry
HCl + NH3 ==> NH4Cl mols HCl = M x L = ? mols NH3 = M x L = ? Which is smaller? That is the amount of NH4Cl formed,
January 23, 2016

Chemistry
See my response above.
January 23, 2016

Chemistry
mass of solution = 158.5 - 145.0 = ? Then density = mass/volume
January 23, 2016

Chemistry
TlOH is a strong base just like NaOH; therefore, (OH^-) = (TlOH) pOH = -log(OH^-), then pH + pOH = pKw = 14. You pOH and pKw, solve for pH.
January 23, 2016

Chemistry
10? 10/22.4 = 0.4446 mols N2. mols He must be 0.446 Then 22.4 L/mol x 0.446 mol = 10 L He.
January 23, 2016

oops Damon--Chemistry
mols M = 6/27 = 0.222 molsl Cl = 23.66/35.5 = 0.666 Find the ratio. The easy way to do that is to divide both numbers by the smaller of the two. 0.222/0.222 = 1 0.666/0.222 = 3 Empirical formula is MCl3. M must be Al.
January 23, 2016

Chemistry
Take a 100 g sample which gives you 50 g C 6.67 g H 100-6.67-40 = 53.33 g O mols C = 40/12 = 3.33 mols H = 6.67/1 = 6.67 mols O = 53.33/16 = 3.33 Find the ratio to each other with the smallest being no less than 1.00. The easy way to do that is to divide all of the numbers by ...
January 23, 2016

chemistry
3NaOH + H3PO4 ==> 3H2O + Na3PO4 mols NaOH = M x L = ? Using the coefficients in the balanced equation, convert mols NaOH to mols H3PO4. Then M H3PO4 = mols H3PO4/L H3PO4 = ?
January 23, 2016

chemistry
Dissolving salt in water raises the boiling point (and lowers the freezing point).
January 22, 2016

science (chemistry)
See my response above.
January 22, 2016

chemistry
No it isn't. Also you will see potassium tetraoxophosphate(V) and that isn't right either. It's potassium phosphate. The other is hydrogen chloride if it is a gas. In aqueous solution it is [HCl(aq)] hydrochloric acid
January 22, 2016

Chemistry
Frankly I don't understand the question. What is a potential fold?
January 22, 2016

Chemistry
Let's call nicotine BH. .......BH + HOH ==> BH^+ + OH^- I.....0.01...........0......0 C......-x............x......x E...0.01-x...........x......x Substitute the E line into the K expression and solve for x = OH^-. Convert that to pOH, then to pH.
January 22, 2016

Chemistry
http://www.jiskha.com/display.cgi?id=1453339010
January 22, 2016

Chemistry
What's the half-life of Rn222? I think that's approx 4 days but you can look that information up in your text/notes. It takes 1 half life to reduce the amount to 1/2 of what you started and another (to make 2 half lives) to reduce another 1/2 or 1/4 (that's 1/2 x 1...
January 22, 2016

Chemistry
Ca + 2H2O ==> Ca(OH)2 + H2 mols Ca(OH)2 = grams/molar mass = ? Using the coefficients in the balanced equation, convert mols Ca(OH)2 to mols H2. Then use PV = nRT OR 1 mol at STP is 22.4L to convert to volume. For grams Ca, g = mols x molar mass.
January 22, 2016

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