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Posts by DrBob222

Total # Posts: 54,282

Chemistry
You don't have enough information to even estimate an answer, much less obtain a real answer. Also, my crystal ball isn't working today.
October 20, 2016

Chemistry
q1 = heat need to change temperature of solid ice at -45 C to solid ice at 0 C. q1 = mass ice x specific heat solid ice x (Tfinal-Tinitial) q2 = heat needed to change solid ice at 0 C to liquid water at 0 C. q2 = mass ice x heat fusion water. Total q = q1 + q2
October 19, 2016

Chemistry
That's my answer also.
October 19, 2016

Chemistry
I worked this for someone just a day or so ago but I can't find it. Here is a summary. This is a limiting reagent (LR) problem and you know that because amounts are given for BOTH reactants. N2 + 3H2 ==> 2NH3 mols N2 = grams/molar mass = ? mols H2 = grams/molar mass...
October 19, 2016

Chemis6
C6H12O6 → 2C2H5OH + 2CO2 mols ethanol needed = grams/molar mass Using the coefficients in the balanced equation, convert mols ethanol to mols glucose Now convert mols glucose to grams. g = mols x molar mass = ? Post your work if you get stuck.
October 19, 2016

Chemistry
PCl5 ==> PCl3 + Cl2 Is this 100% reaction or must you use the Keq (which you don't list).
October 19, 2016

Chemistry
Here is a similar problem. Just change the numbers. http://www.jiskha.com/display.cgi?id=1442613787
October 19, 2016

Chemistry
See your post above.
October 19, 2016

Chem
Bob Pursley worked this problem for you that I saw this A.M. Look for it. Click on bob Pursley's answers and you can find it.
October 19, 2016

chemistry
The answer by Ashley is correct but the equation is not. Here is the correct equation. Zn + 2HCL-->ZnCl2 + H2
October 19, 2016

Science
distance = rate x time 500 mi = 500 mi/hr x time. Solve for time in hours.
October 19, 2016

Chemistry
for f.p. delta T =i*Kf*m i = 3 for Na2SO4 m you have look up Kf. Subtract delta T from 0 C to find new f.p. for b.p. delta T = i*Kb*m look up Kb. You have m and i, add delta T to 100 C to find new boiling point.
October 19, 2016

chemistry
[mass Pb x specific heat Pb x (Tfinal-Tinitial)] + [mass H2O x specific heat H2O x (Tfinal-Tinitial)] = 0 The only unknown here is Tfinal
October 19, 2016

chemistry
See your previous post. Same kind of problem. Post your work if you get stuck.
October 19, 2016

chemistry
Wouldn't you think N2 < NO2 < KCl?
October 19, 2016

beginning algebra
Plug in 1 for x and solve for y. Plug in 2ffor x and solve for y. Plug in 3 for x and solve for y. Need more? Plug in a number for x or y and solve for the other.
October 19, 2016

Chemistry
(V1/T1) = (V2/T2)
October 19, 2016

Chem
It helps us help you better when you use the same screen name. You didn't do that but see your other post above.
October 19, 2016

chemistry
KCl + Br2 = no reaction
October 19, 2016

chemistry
no reaction. Cl2 and KBr is yes, Br2 and KCl none.
October 19, 2016

chemisty
1 mol of atoms contains 6.02E23 atoms.
October 18, 2016

chemi
See your other post.
October 18, 2016

chemistry
1 mol of molecules contains 6.02E23 molecules.
October 18, 2016

chemistry
See your other posts. All of these are essentially duplicate posts. There are 6.02E23 anythings in 1 mol of anythings.
October 18, 2016

chemistry
Your question is poorly worded in my opinion. By my definitions, if the H2SO4 is neutralized then there will not be ANY H2SO4 left. What the problem means, I think, is after the addition of that much KOH to that much H2SO4, what is the concn of H2SO4. H2SO4 + 2NaOH ==> ...
October 18, 2016

Chemistry
It's tough reading with no caps and no periods and/or question marks. Yes, ice water Ti is 0 and Tf final T of solution. Ti for warm water is unknown. Tf is same for ice water and warm water.
October 18, 2016

Chemistry
heat gained by ice water (you know both Tfinal and Tinitial) + heat lost by warmer water (Tfinal which you know and Tinitial which you don't know) = 0. What's the only unknown in the equation?
October 18, 2016

Chemistry
Reacted with what? O2? 2C2H2 + 5O2 ==> 4CO2 + 2H2O mols C2H2 = grams/molar mass = ? Then H2O = mols C2H2 x (2 mols H2O/2 mols C2H2) = ? mols H2O Convert mols H2O to grams. grams H2O = mols H2O x molar mass H2O
October 18, 2016

chemistry
I don't understand what you want with a skeleton equation. But here is the equation. CuCl2 + Li ==> LiCl + Cu You can balance it?
October 18, 2016

chemistry
See your other post.
October 18, 2016

Chemistry
Ksp AgI = (Ag^+)(I^-) You know Ksp and I^-, solve for Ag^+. Same for AgBr and AgCl. b part. What is Ag^+ when AgBr first ppts. You calculated that above. Plug Ag+ from the AgBr when it first ppt into Ksp for AgI to find the I^- concn when AgBr starts. Then %I left at that ...
October 18, 2016

Chemistry
ok
October 18, 2016

chemistry
dq = mass Au x heat fusion
October 18, 2016

chemistry
q = mass ethyl alcohol x heat vap
October 18, 2016

Chemistry
You didn't quit soon enough. The answer is 25 cc = volume. That's the end of the problem. The problem DID NOT ask for the volume of the sides and even if it had the problem didn't say it was a cube with equal dimensions.
October 18, 2016

chemistry
See your posts above.
October 18, 2016

Chemistry
Almost. I arrived at 14.77 on my calculator, also, but you are allowed only three significant figures. So that 14.77 is rounded to 14.8 g
October 18, 2016

CHEM 1411
g CaSO4 = 0.0.6168 x (molar mass CaSO4/molar mass BaSO4) = ? Then % CaSO4 = (g CaSO4/mass sample)*100 = ? mass of sample is 0.4550g
October 18, 2016

Chemistry
0.177, not 0.1777. Then 0.000522 = 0.177/x x = 0.177/0.000522 = 338.9 which rounds to 339. Your line three doesn't follow from line 2. Line 2, except for the extra 7 in the grams is ok. I don't know where the 380 came from. If you had finished and shown how you ...
October 17, 2016

Chemistry
You leave us in the dark with this. Instead of saying you tried everything, post what you tried and let us find the error. This we're playing guessing games.
October 17, 2016

Chemistry
I don't see any answer you posted; I see only questions. NaOH + HA ==> NaA + H2O 1 mol NaOH = 1 mol HA so mols NaOH from above = mols HA. Then mols = grams/molar mass or molar mass = grams/mols. If you did g/mols, I suggest you post your work and let us look at it.
October 17, 2016

Chemistry
mols = M x L = ?
October 17, 2016

Chemistry
You need to provide us information on what you were doing.
October 17, 2016

Chemistry
Are you sure that was 0.7374 g Ca? or was it CaCO3. The answer below is for 0.7374 g Ca. 0.7374 x (molar mass Ca citrate/atomic mass Ca) = ? For other metals look for other carbonates that are insoluble; ;i.e., Mg might be one.
October 17, 2016

honors chem
(0.8020*11.01)+(0.1980*x) = 10.81 Solve for x
October 17, 2016

Chemistry Plz Help!
Starting with what?
October 17, 2016

Thermochemistry
What reaction?
October 17, 2016

chemistry
0.5 what? KCO3. No such animal.
October 17, 2016

chemistry
Kd = 4.0 = [(x/20)/(100-x)/50] Solve for x = amount in the methylene chloride layer. 100-x is the amount in the water.
October 17, 2016

chemistry
% mass w/w means (gsolute/total g)*100 = ? [17.35/(17.35+x)]*100 =22.5 Solve for x
October 17, 2016

Chemistry
A two-step problem. First, determine the specific heat of Co from sample A. q = mass Co x specific heat Co x (Tfinal-Tinitial). The only unknown in this equation is specific heat Co in sample A. Specific heat doesn't change. NHow use the same formula for sample B of Co. q...
October 17, 2016

Chemistry
I worked a problem just like this last night. Post your work if you run into trouble. http://www.jiskha.com/display.cgi?id=1476638100
October 17, 2016

Chemistry
See your other post above.
October 17, 2016

Chemistry
glad you figured it out.
October 17, 2016

Inorganic Chemistry
1.577 M is 1.577 mols/L solution. With density = 1.220 g/mL, then substitute volume and density to find mass of the solution. 1.577 mols AgNO3 x molar mass AgNO3 = grams AgNO3. Then mass solution - g AgNO3 = mass solvent. Convert that to kg. m = 1.577 mols AgNO3/kg solvent
October 16, 2016

Inorganic Chemistry
1 molal means 1 mol solute in 1 kg solvent. mols solute = 1.00 mols solvent = 1000/18 = ? Total mols = 1.00 + ? from above. Then Xsolute = 1.00/total mols.
October 16, 2016

homework dump?---chem
I see a lot of question here with no effort on your part. I worked the last two. I can help with the others but HELP is the key word.
October 16, 2016

Chemistry
(0.788&25.5)+(1-0.788)*X = 29.5 Solve for X.
October 16, 2016

Chem 125
A multistep problem but simple to do. Use P1V1 = P2V2. For example, calculate the total volume by adding the volumes of each bulb. Don't forget to add in the volume of the tubing. Bulb 1 is 37.0 mL with P of 5.65 atm. So P1 is 5.65, V1 is 37.0 mL, V2 is the total volume ...
October 16, 2016

Chemistry
mols camphor = grams/molar mass = 25.0/152.24 = approx 0.15 but that's an estimate you should recalculate it. The number of molecules is 6.02E23 molecules in 1 mol so in 0.15 mols there will be approx 0.15 x 6.02E23 = approx 1E21. The formula is C10H16O. There are 27 atoms...
October 16, 2016

chemistry
See your other post.
October 16, 2016

Chemistry a level
1. Write and balance the equation. 2MnO4^- + 5C2O4^2- + ? ==> 2Mn^2+ + 10CO2 +? I didn't finish the entire equation (that is I omitted the H^+, electrons, and H2O) BUT I balanced the redox part and that's all you need. 2. mols Na2C2O4 = grams/molar mass = ? 3. Using...
October 16, 2016

chemistry
Zn is above H in the activity series and silver is below H in the same series.
October 16, 2016

Chem
pOH = 0.650 -0.650 = log(OH^-) (OH^-) = 4.47 M Ca(OH)2 = 1/2 that or 2.23 M
October 15, 2016

CHEMISTRY
q = heat absorbed = mass Cu x specific heat Cu x (Tfinal-Tinitial). The sign will be +.
October 15, 2016

chem
First determine theoretical yield (TY). The actual yield (AY) is given as 1.24g. mols CaCO3 = grams/molar mass = ? Look at the equation. You get 1 mol CaO for every 1 mol CaCO3; therefore, mols CaCO3 from above will give you that many mols CaO. Convert mols CaO to grams. g = ...
October 15, 2016

chemistry
With all gases in the equation one may use a shortcut in which volumes are considered as mols. Convert 10 L O2 to ? L CO2. 10 L O2 x (3 mols CO2/5 mols O2) = 10 x 3/5 = ? L CO2.
October 15, 2016

chemistry
1.50 M x (75.0 mL/278 mL) x [139 mL/(139+139)] = ?
October 14, 2016

Science-chemistry
You need the molar mass of the compound if that is the molar enthalpy of formation of the compound. 100,000 g/molar mass = ? mols compound. What reaction is that -63 kJ/mol for?
October 14, 2016

Chemistry
heat lost by one + heat gained by other = 0. [mass Au x specific heat Au x (Tfinal-Tinitial)] + [mass granite x specific heat granite x (Tfinal-Tinitial)] = 0 Substitute and solve for only unknown, i.e., Tfinal.
October 14, 2016

lab chimistry
What compound? What's the experiment?
October 14, 2016

chemistry 11
If I divide 35.88 by 100 to get 0.3588 and divide that by 1.35 I get 0.266 for salt. sand = 65.11 (which I would round to 65.12 from the numbers); then 0.6512/3.17 = 0.205 Confirm those values and look at your calculations again. As for a negative %error, that just means the ...
October 14, 2016

chemistry 11
See your post above.
October 13, 2016

Chemistry
1. What is the concentration of TEOS? 2.What is TEOS?
October 13, 2016

college chemistry
mols NO = grams/molar mas = ? Using the coefficients in the balanced equation, convert mols nO to mols O2. That ratio is 4 mols NO/5 mols O2. Then remember that one mole of a gas at STP occupies 22.4 L.
October 13, 2016

Chemistry
mass Fe used = 0.32239. Convert that to mols. mols Fe = g/atomic mass = ? Using the coefficients in the balanced equation, convert mols Fe to mols Cu product. That's ?mols Fe x (3 mols Cu/2 mols Fe) - ?mols Fe x 3/2 = ? Then convert mols Cu formed to grams. g Cu = mols Cu ...
October 13, 2016

chem
The titration is HCl + NaOH ==> NaCl + H2O mols NaOH used = M x L = approx 0.01 but you need to confirm that.Since the ratio in the titration is 1 mol NaOH to 1 mol HCl, that means mols HCl in that 25 mL aliquot is the same as mols NaOH used to titrate it. Since this was a ...
October 13, 2016

Chemistry
The advantage is that most of the Mg and Ca ions are removed which means less detergent needed to clean. It also means less "bathtub" ring when the Ca and Mg ions react with soap. The con is that the Ca and Mg ions are replaced with Na ions and most health agencies ...
October 13, 2016

chemistry
equivalents = grams/eq weight = 4/40 = ? N = eq/L = ?
October 13, 2016

chemistry
Frankly, I haven't called these the H, or B or C groups. I have used alkali metal group, alkaline earth group, halogen group, noble element group, etc. There is much confusion about how the columns are numbered in the periodic table but if you understand the different ...
October 12, 2016

Chemistry
Two. There is 1 mol NH4^+ and another 1 mol Cl^-.
October 12, 2016

chem
I showed you how to do part a last night. You should have posted the entire problem then.
October 12, 2016

Chemistry
1 and 3 don't react so just the aq ions of those materials present. No ppts, no gases, etc. 2 forms CoPO4(s) PO4^3- + Co^3+ ==> CoPO4
October 12, 2016

Chemistry
CO3^2- + 2H^+ ==> CO2 + H2O
October 12, 2016

Chemistry
Cl^- + Ag^+ ==> AgCl mols Ag^+ = M x L = ? Because of the 1:1 ratio mols Cl^- = mols Ag^+. Then g Cl^- = mols Cl- x atomic mass Cl-
October 12, 2016

Chemistry
H2CO3 + 2NaOH ==> Na2CO3 + 2H2O OR H2CO3 + NaOH ==> NaHCO3 + H2O This problem is not workable with the information given. The titration of H2CO3 has TWO endpoints as shown in the two equations above. If phenolphthalein is used as the indicator the second equation is in ...
October 12, 2016

Chemistry
Not Zn^2+. It's Zn and for the reason you cite. Zn ==> Zn^2+ + 2e has the highest oxidation potential
October 12, 2016

Chemistry
Thank you Bob Pursley.
October 12, 2016

@Damon--Chemistry
I don't think there is enough information to answer this question. I believe the answer posted is for a 500 GRAM solution but it won't be 500 mL. The density of a 37% H2SO4 solution is right at 1.05 g/mL so the volume will be about 476 mL. Have I missed the boat? I ...
October 12, 2016

Chemistry
Is this0.15 m or 0.15 M Is there a part b?
October 12, 2016

0.5mols of a monoalkanoicacid weighs 44 grams, determine the molecular formula and name the acid. (show the workings)
See your other post.
October 12, 2016

chemistry
mols = grams/molar mass. You have mols and grams, solve for molar mass. I get 88. The COOH group of an alkanoic acid weighs has a molar mass of 45 which leaves88-45 = 43. A methyl group (CH3) is 15 while the methylene group (CH2) is 14 so I would make an educated guess that ...
October 12, 2016

Basic science chemestry
Do you have a question? What you have posted is confusing. By the way you need to learn how to spell chemistry.
October 12, 2016

Chemistry
#1
October 12, 2016

Chemistry
I can draw the three for 1. For 2 I can draw two; i.e., 1-hydroxy propane and 2-hydroxy propane although those may not be proper IUPAC names. For 3 I can draw any structure for C2H4Cl and certainly not three. I can draw for at least one structure for C2H5Cl, at least one for ...
October 12, 2016

Chemistry
Let's call CH3COOH just HAc. It is dissociates 50%, that means it starts at 0.2M and ends up at 0.1M with the products 0.1M .........HAc --> H^+ + Ac^- I........0.2.....0......0 C....-0.5*0.2...0.1.....0.1 E.......0.1.....0.1.....0.1 Plug this into the Ka expression but...
October 12, 2016

chemistry
If you have pure Cu and you add oxygen to it, the Cu forms CuO and the Cu gains weight (mass) because of the added oxygen.
October 12, 2016

Chemistry
It does dissolve directly in water.
October 12, 2016

Chemistry
Basically, gases are compressible while liquids and solids are not. Doubling the temperature doubles the volume of a gas; certainly the volume of a solid and volume of a liquid are not doubled. Solids, liquids, and gases simply don't have the same properties.
October 12, 2016

Chemistry
CuO + H2 ==> Cu + H2O
October 12, 2016

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