Monday
September 26, 2016

Posts by DrBob222

Total # Posts: 53,142

chemistry
http://www.webexhibits.org/causesofcolor/7G.html
March 4, 2016

Chemistry
rate1 = k1*(Q1)^a*(X1)^b where a and be are the exponents for the orders and (Q) and (X1) are the concentrations for rate 1. rate2 = k2*(Q2)^a*(X2)^b Then rate1......(k1*(Q1)^a*(X)^b ------------------------ rate2......(k2)*(Q2)^a*(X)^b Pick trial 1 and 2 since (X) is the same...
March 4, 2016

Chemistry
We're at a loss to draw diagrams on this forum. I'm sure you can find appropriate diagrams along with the appropriate explanations on Google.
March 4, 2016

Chemistry
The PE starts at a higher point than at the end, the difference is the amount of energy emitted.
March 4, 2016

Chemistry
It makes no difference: you didn't tell us what you did or even what the experiment was.
March 4, 2016

Chemistry
Convert g CO2 to g C. 0.320 g CO2 x (12/44) = ? Convert g H2O to g H. 0.0874 x (2/18) = ? Then g O = 0.214 - g C - g H. % C = [g C/0.214]*100 = ? % O = [g O/0.214]*100 = ? % H = [g H/0.214]*100 = ? Now take 100 g sample which will give you those percentages as g C, H, O. ...
March 3, 2016

chemistry
2) (V1/T1) = (V2/T2). Remember T must be in kelvin. The problem gives no initial volume except V. You can do either of two things. a. Assume any number for V1; then V2 will be twice that number. b. Just call the initial volume V1, then V2 will be 2V1. 5). Same procedure as 2) ...
March 3, 2016

Chemistry
I think you're looking for this. Just add the two equations you multiplied to get the electrons equal. 2In + 3Cd^2+ ==> 2In^3+ + 3Cd
March 3, 2016

AP CHEM
I answered a question quite similar to this a couple of days ago. There is no BaCl2 in solution. There are Ba ions and chloride ions and there are more chloride ions than barium ions. But to try to calculate a M of an ionic compound in which the positive barium ions and the ...
March 3, 2016

chemistry
q1 = heat needed to change phase of ice from solid at zero C to liquid at zero C is q1 = mass ice x heat fusion = ? q2 = heat needed to raise the T from zero C to 85 C. q2 = mass H2O x specific heat H2O x (Tfinal-Tinitial) = ? q total = q1 + q2
March 3, 2016

Chemistry
new mols = 0.178 + 0.094 = ? Then PV = nRT. Remember T must be in kelvin.
March 2, 2016

Chemistry
I would put it slightly differently. Molality is mols per kg SOLVENT ir mols/kg solvent. M usually stands for molarity and not mols. m usually stands for molality. I usually write m = mols/kg solvent.
March 2, 2016

Chemistry
Keep this procedure. It will come in handy working about 90 of the stoichiometry problems. 1. Write and balance the equation. 2Na + O2 ==> Na2O 2. Convert grams (usually given) to mols which is mols = grams/molar mass. In this case mols are given in the problem so this step...
March 2, 2016

Chemistry
Why didn't you tell us what you used as the limiting reagent? I could have found the error. AgNO3 + NaCl ==> AgCl + NaNO3 mols AgNO3 = M x L = 0.0576 mols NaCl = M x L = 0.064 So AgNO3 will form 0.0576 mols AgCl. NaCl will form 0.064 molg AgCl. The correct answer in ...
March 2, 2016

Chemistry
Let's call lactic acid HL. .........HL ==> H^+ + L^- I.....0.027M....0.....0 C.......-x......x.....x E....0.027-x....x.....x Look up Ka for Lactic acid and substitute the E line above into the Ka expression and solve for x = (H^+), then convert that to pH. Remember that...
March 2, 2016

Chem
I think you are looking for N-H and N-N bonds as sigma bonds.
March 2, 2016

Chemistry
The problem asks to show the states, also. The equation is correct. 2H2S(g) + 3O2(g) --> 2SO2(g) + 2H2O(g) Note the problem TELLS you the water is vapor so you know to write it as a gas and not a liquid.
March 2, 2016

Chemistry
https://answers.yahoo.com/question/index?qid=20110323110631AA6R4NF
March 2, 2016

Chemistry
Mg is oxidized to Mg^2+. Mg ==> Mg^2+ + 2e Cu^2+ is reduced to Cu(s) metal. Cu^2+ + 2e ==> Cu
March 1, 2016

Chemistry
I don't get the "or reacted". I assume you want the volume of H2 corrected to STP. Look up the vapor pressure of water at 10 C. Ptotal = pH2O + pH2 105.5 = vap pressure H2O + pH2 and solve for pH2. Then PV = nRT and solve for V. Remember to use the same units for...
March 1, 2016

Chemistry
q = mass H2O x specific heat H2O x (Tfinal-Tinitial) You are looking for q. mass is given, you need to look up specific heat H2O (4.184 J/g*C) and you have Tfinal and Tinitial. Solve for q.
March 1, 2016

Chem
I thought I answered this yesterday.
March 1, 2016

chemistry
acetic acid is HAc. .........HAc ==> H^+ + Ac^- I..l....0.31.....0......0 C........-x......x......x E......0.31-x....x......x Substitute the E line into the Ka expression and solve for x. Then % ion = [(x)/0.31]*100 = ?
March 1, 2016

chemistry
See your post above.
March 1, 2016

Chemistry
You have it balanced except for the 8H2O. Just add 8H2O on the end. Na2SO4+Ba(OH)2*8H2O=BaSO4+2NaOH + 8H2O g Na2SO4 = 0.853 x 0.95 = ? g Ba(OH)2*8H2O = 1.707 x 0.87 = ? Convert to mols. mols Na2SO4 = grams/molar mass = ? mols Ba(OH)2*8H2O = grams/mola mass = ? Using the ...
March 1, 2016

Chemistry
This is not a very good problem because not all of the Ba(OH)2 is used AND because there is no BaCl2 formed. All of the Ba^2+ and all of the Cl^- is there that you started with; i.e., no actual BaCl2 is formed. So I don't understand what the problem wants since there is no...
March 1, 2016

Chemistry
H2SO4 + 2NaOH ==> Na2SO4 + 2H2O mols NaOH = M x L = ? mols H2SO4 = 1/2 x mols NaOH (Look at the coefficients in the balanced equation.) Then M H2SO4 = mols H2SO4/L H2SO4 = ?
March 1, 2016

Chemistry
Cr(NO3)3(aq) + 3NaOH(aq) ==> Cr(OH)3(s) + 3NaNO3(aq) Now you convert that balanced molecular equation into a balanced ionic equation. Cr^3+(aq) + 3(NO3^-)(aq) + 3Na^+(aq) + 3OH^-(aq) ==> Cr(OH)3(s) + 3Na^+(aq) + 3NO3^-(aq) and here are the rules you follow. 1. Gases ...
March 1, 2016

Chemistry
I don't think it is. Single replacement reactions are the type AX + Y = YX + A The reaction above is AX + Y = AY + YX
March 1, 2016

Chemistry
.............HA ==> H^+ + A^- I...........0.1.....0.....0 C...........-x......x.....x E.........0.1-x.....x.....x The problem tells you pH = 2.44. Convert that to (H^+) by pH = -log(H^+) and substitute the x value in for (H^+) and (A^-). Evaluate 0.1-x and substitute that ...
March 1, 2016

Chemistry (stoichiometry)
2C6H6 + 15O2 ==> 12CO2 + 6H2O 22 mols C6H6 x (12 mols CO2/2 mols C6H6) = 22 x 12/2 = ? mols H2O = grams/molar mass = ? Then ?mols H2O x (12 mols O2/6 mols H2O) = ? mols H2O x 12/6 = xx
March 1, 2016

Chemistry- Dr.Bob
The 80 x specific heat ice x 15 = heat absorbed in changing the T of ice at -15 to zero C. Then you melt the ice and convert solid ice to liquid water with 80 x heat fusion ice. Then you combine the moving T to zero with melting and see if the 250 g water at 85 is enough to ...
March 1, 2016

Chemistry-Dr.Bob 222
That doesn't help me. I don't remember if I answered this or not and if I did what I said. If I answered, copy that and explain what you don't understand.
March 1, 2016

@pradeeo---Chemistry
I don't believe H2C2O4 has an equivalent weight of 63. The molar mass is 90 and it is diprotic; therefore, the equivalent weight is 45.
March 1, 2016

Chemistry
A common ion is just what you think it is. For example, a solution of NaNO3 and KNo3 has a common ion; i.e., the NO3^-. AgCl saturated solution with AgBr (or NaCl)O has a common ion. A buffer basically is a weak acid and its salt (such as acetic acid and sodium acetate) or a ...
February 29, 2016

Chemistry
The rxn is Fe + Cu^2+ ==> Cu + Fe^2+ so the electrons flow from Fe to Cu^2+. The anode is where oxidation occurs. Since the Fe is going into solution and the Cu^2+ is coming out of solution, the Cu side has too many nitrate ions.
February 29, 2016

Chemistry
Zn, Pb, Mg, Al, Ca will reduce Ag^+ to Ag BUT they also will reduce Sn^2+. See this site. http://www.csudh.edu/oliver/chemdata/data-e.htm
February 29, 2016

Chemistry (Food)
The answer is A IF that is 4 kcal for carb and 9 kcal for gat. Those periods after the ) sign bother me. That must be 4 and not .4.
February 29, 2016

Chemistry
I would do this. Note N changes, Br changes BUT some of the Br^- are 1- on the left AND 1- on the right so they don't change. When this happens balance the redox part then add enough Br^- in the final equation for those Br^- that don't change. 6e + 2N^3+ ==> N2 3H2O...
February 29, 2016

Chemistry... again
A polar bond has a charge separation while a non-polar bonds does not. That is, a Cl-Cl bond has equal pull on the electrons for each atom, each attracts those outside electrons equally, neither atom wins, and the electrons are distributed evenly. For the HCl bond, however, ...
February 29, 2016

Chemistry
The easiest to pull electrons away from is the largest.
February 29, 2016

Chemistry
acetic acid = HAc ......HAc + H2O ==> H3O^+ + Ac^- I....0.1......0......0 C....-x.......x......x E...0.1-x.....x......x Substitute the E line into the Ka expression and solve for H3O^+
February 29, 2016

Chemistry
See our other post.
February 29, 2016

chemistry
1. How many moles do you need? That's mols = M x L = ? Then convert to grams. mols = g/molar mass. You know mols and molar mass, solve for grams. 2. Use the dilution formula. mL1 x M1 = mL2 x M2 mL1 x 0.5 = 100 x 0.1 Solve f r mL1.
February 29, 2016

Some Chemistry Questions
1 and 2 are wrong. 3 is ok.
February 29, 2016

Chemistry
acetic acid = HAc NaC2H3O2 is NaAc mols NaAc = grams/molar mass = ? Then mols NaAc/0.250 = ?M mols HAc = molsL. mols = M HAc x L HAc volume = 0.250 L M = mols/L.
February 29, 2016

Chemistry
What is that set up. If can see what you're talking about I can walk you through each step.
February 29, 2016

Chemistry
........HA ==> H^+ + Ac^- I....0.095.....0.....0 C......-x......x.....x E...0.095-x....x.....x The problem tells you that the pH is 5.42 which means you can calculate (H^+) from pH = -log(H^+) and that is x in the above. Then (Ac^-) is the same and you can calculate 0.095-x...
February 29, 2016

Chemistry
That looks ok to me.
February 29, 2016

Chemistry
AgCl(s) ==> Ag^+ + Cl^-. Write Ksp for this. Ag^+ + 2NH3 ==> [Ag(NH3)2]^+ Write Kformation for this one. Overall is is AgCl + 2NH3 ==> [Ag(NH3)2]^+ + Cl^- Wrote Keq expression for this. Then if you will multiply Ksp*Kformation you will get the overall equilibrium ...
February 29, 2016

Chemistry
H2SO4 + 2NaOH --> 2H2O + Na2SO4 mols H2SO4 = M x L = ? Using the coefficients in the balanced equation, convert mols H2SO4 to mols NaOH. Then M NaOH = mols NaOH/L NaOH. You know mols and M, solve for L and convert to mL.
February 29, 2016

Chemistry
The limiting reagent controls the amount of product(s) formed.
February 29, 2016

cHEMISTRY
2AgC2H3O2 + MgCl2 ==> 2AgCl + Mg(C2H3O2)2 mols MgCl2 = grams/molar mass = ? Using the coefficients in the balanced equation convert mols MgCl2 to mols AgCl. Then convert mols AgCl to mass. g AgCl = mols AgCl x molar mass AgCl.
February 29, 2016

Chemistry
.........2CH4 ==> C2H2 + 3H2 I ......0.087......0......0 C........-2x.......x......3x E.....0.087-2x.....x......3x The problem tells you that 3x = 0.012 which allows you to calculate x and 0.087-2x (as well as 3x). Substitute those values into the Keq expression and ...
February 28, 2016

chemistry
First, I wouldn't start that way. Convert torr to atm; i.e., 310/760 = pi = ? pi = MRT. You know pi, R (0.0820), and T (in kelvin please). Solve for M = molarity. Then M = mols/L. You know M and L (or can convert to L), solve for mols. Then mols = grams/molar mass. You ...
February 28, 2016

Chemistry
So delta T = 0-(-3.55) = ? delta T = Kf*m You know delta T and Kf, solve for m = molality
February 28, 2016

Chemistry
mols KCl = grams KCl/molar mass KCl = ? Then M = mols/L solution.
February 27, 2016

Chemistry
I don't think anyone here is likely to do all of your work for you; however, if you will tell us exactly, and in detail, what you don't understand, perhaps we can help.
February 27, 2016

analytical chemistry
mL1 x M1 = mL2 x M2 20 x 0.1 = mL2 x 0.02 Solve for mL2 which gives you the FINAL volume. Subtract the final - initial to find amount to be added. Technically, that will not be right since volumes are not additive but for dilute solutions like this the difference is minuscule.
February 27, 2016

Chemistry
Zn + 2HCl ==> ZnCl2 + H2 mols Zn = grams/atomikc mass = ? Using the coefficients in the balanced equation, convert mols Zn to mols H2. Since this is a 1:1 reaction, mols H2 = mols Zn. Then use PV = nRT to solve for V at the conditions listed. Remember T must be in kelvin ...
February 27, 2016

Chemistry
Do you have a reaction equation? One source gives Fe2O3 as the product; another gives Fe3O4 as the product. The answer to this question depends upon which product is formed. I will assume Fe2O3 and go from there. 2Fe + 3H2O ==> Fe2O3 + 3H2 Use PV = nRT and solve for n = ...
February 27, 2016

chemistry
mols Fe2O3 = grams Fe2O3/molar mass Fe2O3 Then there are 2 mols Fe for every 1 mol Fe2O3.
February 26, 2016

Chemistry
n*lambda = 2d sin angle.
February 26, 2016

Chemistry
+7 K = +1 O = -2 and 4*-2 = -8 What must Cl be for KClO4 to be zero. Remember that all compounds or elements in the free state are zero total. +1 + ? + (-8) = 0
February 26, 2016

Chemistry
I disagree with Nerd. This is a limiting reagent (LR) problem. N2 + 3H2 ==> 2NH3 a. Convert 2 L N2 to mols NH3 produced if we had all of the H2 needed. That is 2 L N2 x (2 mols NH3/1 mol N2) = 2 x 2 = 4 L NH3 b. Convert 2 L H2 to mols NH3 produced if we had all of the N2 ...
February 26, 2016

chemistry
Note the correct spelling of Celsius. .........N2O4 <-> 2NO2 I........1.680.....1.220 C.........-p.......+2p E........1.680-p...2p The problem tells you that 2p = 0.550. You can calculate p from that. That allows you to evaluate 1.680-p Then substitute these values into ...
February 26, 2016

CHE 2B
1. Use the HH equation. pH = pKa + log (KNO2)/(HNO2) 2. Without values of pKa any thing I calculate won't agree with your calculations. Here is what you do. .......HNO2 + OH^- ==> NO2^- + H2O I......12.5....0........9.25 add............2............ C......-2.....-2...
February 26, 2016

chemistry
2C2H2 + 5O2 ==> 4CO2 + 2H2O Use PV = nRT for O2. Plug in 155 atm for P, V = 5.5L, Assume any value for T(in kelvin) and use your chosen value for T throughout. Solve for n = number of mols O2. Knowing you need that many mols O2, use the coefficients in the balanced equation...
February 26, 2016

Chemistry
Why don't you use sodium hydrogen carbonate for the name. Bob Pursley gave you the right procedure and the right numbers. That 84 should be for NaHCO3.
February 25, 2016

Chemistry
79 x 0.225 =
February 25, 2016

Chemistry
C7H16 + 11O2 ==> 7CO2 + 8H2O mols CO2 = grams/molar mass = 37.5/44 = approx 0.85 Convert mols CO2 to mols C7H16 using the coefficients in the balanced equation. approx 0.85 x (1 mol C6H16/8 mols CO2) = approx 0.85 x 1/8 = 0.1 mol C7H16 g C7H16 = mols C7H16 x molar mass ...
February 25, 2016

Chemistry
See your previous post.
February 25, 2016

Chemistry
5. Consider the following reaction: CO2 (g) + H2 (g) CO (g) + H2O (g) Calculate the value of the equilibrium constant, Kc, for the above system, if 0.1908 moles of CO2, 0.0908 moles of H2, 0.0092 moles of CO, and 0.0092 moles of H2O vapour were present in a 2.00 L reaction ...
February 25, 2016

Chemistry
You should post each question separately. Some won't answer posts that too long; i.e., consists of several questions. Calculate the pH of a NaOH solution of concentration 0.5M (Kw = 1.0 x 10-14 mol2dm-6 at 25oC) (H^+)(OH^-) = Kw. Substitute and solve for (H^+) [note that...
February 25, 2016

Chemistry
You want to compare Ksp with Qsp. (AgNO3) = 1E-4 x (200/1100) = ?M (KCl) = 1E-6 x (900/1100) = ?M Qsp = (Ag^+)(Cl^-) = ? If Qsp > Ksp a ppt forms. If Qsp < Ks no ppt forms.
February 25, 2016

educational tec connections academy
pitiful
February 25, 2016

Chemistry
I don't think so. mols you need = M x L = ? Then grams = mols x molar mass = ?
February 25, 2016

Chemistry
It has an alkane (the ethyl) and a phenol
February 25, 2016

Chemistry
See your other post.
February 25, 2016

chemistry
2H2C2O4 + O2==> 2H2O + 4CO2
February 25, 2016

Chemistry
I didn't know they were. Have you measured the temperature of the liquids in those containers? That is, how do you know the liquids are colder?
February 25, 2016

Chemistry
The lactate ion is hydrolyzed by the water in the solution. L^- + H2O ==> HL + OH^- so the solution will be alkaline.
February 25, 2016

chemistry
Which means what?
February 24, 2016

Chemistry
Let mass urea = X mass H2O = 50.9-X mols urea = X/molar mass urea = ? mols H2O = (50.9-X)/molar mass H2O = ? Total mols = X + (50.9-X)/molar mass H2O Substitute and solve for X. I believe X is approx 11 grams. Then mols urea/total mols = 0.769
February 24, 2016

Chemistry
I assume you mean Ni(NO3)2. In chemistry you need to find the caps key on your keyboard and use it. CO, Co, and co are not the same. mols Ni(NO3)2 = grams/molar mass = ? Then M = mols Ni(NO3)2/L solution = ?
February 24, 2016

chemistry
I would prefer you call them nitrate and not that gibberish. 4 LiNO3 → 2 Li2O + 4 NO2 + O2 2 KNO3 ↔ 2 KNO2 + O2 2 Ca(NO3)2 → 2 CaO + 4 NO2 + O2
February 24, 2016

AP Chemistry
This is a limiting reagent. HCl + NaOH ==> NaaCl + H2O mols HCl = M x L = ? = approx 1.4 mols NaOH = M x L = ? = approx 0.46 So the amount of NaCl formed is 0.46 mols. The volume is 400 + 200 = 600 mL = 0.6 L M = mols/L
February 24, 2016

Chemistry
All I can do is to balance these for you and that won't help you at all. If you want to show what you have, especially for the one you know, perhaps we can help. Here is a site that may help, also. http://www.chemteam.info/Redox/Redox.html In 1, Cr goes from zero on the ...
February 24, 2016

Chemistry lab
1. By reaching constant weight you know you have driven off all of the water it contains. 2. If allowed to stand in air the alum will reabsorb, from the air (which contains some water), some of the water diven off by previous heating. Cooling it in a desiccator keeps it from ...
February 23, 2016

Chemistry (balancing equations)
No it isn't and you should never need to ask because you can count atoms on both sides. They will be the same if balanced. I see 6 O atoms on the left (2*3 = 6) and only 3 on the right. Also 2 N on the left and 1 on the right. Not balanced.In addition the formula for ...
February 23, 2016

Orgo
Can't draw pictures on this forum.
February 23, 2016

Chemistry
Technically you can't calculate this because, technically the volumes are not additive. In practice they are with very little error in this case so assuming the volume are additive do it this way. Follow the same procedure for the second problem you posted. mL1 x M1 = mL2 ...
February 23, 2016

chemistry
This is a limiting reagent (LR) problem and you know that because amounts are given for both reactants. 3Mg(NO2)2 + 2Li3PO4 ==> Mg3(PO4)2 + 6LiNO2 mols Mg(NO2)2 = grams/molar mass = ? mols Li3PO4 = grams/molar mass = ? Using the coefficients in the balanced equation, ...
February 23, 2016

chemistry
See your post above.
February 23, 2016

CHEMISTRY! HELP
#2 is easy. There is no reaction. #1. This is a limiting reagent (LR) problem. You know that because amounts are given for both reactants. First you need to balance the equation. 2CuNO3 + MgCl2 ---> 2CuCl + Mg(NO3)2 mols CuNO3 = grams/molar mass = ? mols MgCl2 = grams/molar...
February 23, 2016

Chemistry
Carboxylic acid is correct. The OH group is a phenol group (an alcohol on R group but phenol group when attached to an aromatic ring (AR).
February 23, 2016

Chemistry
Isotonic, hypotonic, hypertonic when compared to what. Iassume you mean when compared with NORMAL saline which is 0.9% NaCl. I would convert 0.9% NaCl to M and use pi = i*MRT to calculate the osmotic pressure. Then convert all of the solution to M and pi. Compart with the ...
February 23, 2016

Chemistry
Let;s call pyridine just B and we know that is a base. ............B + HOH ==> BH^+ + OH^- I........0.02........0.02*0.0003 for BHY and 0.02*0.0003 for OH. Substitute that into the Kb and solve for Kb.
February 23, 2016

Chemistry
H2SO4 + Ba(OH)2 ==> BaSO4 + 2H2O mols Ba(OH)2 = M x L = ? mols H2SO4 = mols Ba(OH)2 M H2SO4 = mols H2SO4/L H2SO4.
February 23, 2016

Chemistry
This done the same way as the BaSO4 problem.
February 23, 2016

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