Wednesday
July 23, 2014

Posts by DrBob222


Total # Posts: 43,165

chem
See the next post up.

chem
See two posts up.

chem
See three posts up.

chem
See four posts up.

chem
(V1/T1) = (V2/T2)

chem
(V1/T1) = (V2/T2) Remember T must be in kelvin. Standard T is 273K

chem
P1V1 = P2V2. If you eneter P1 in atm then P2 will be in atm and you will need to convert to torr. Or you can convert 2.93 atm to torr (1 atm = 760 torr) initially and the final P will be in torr.

chem
I don't understand the question.

chemistry
See your earlier post.

chemistry
Use P1V1 = P2V2. Since no "real" value is given for P1 you can assign any convenient number for P1, then 16 times that will be P2 and work the problem OR you can simply subsitute 16*P1 for P2.

simplify the expression
What do you mean they don't match? 14^-4 = 1/(14^4) = 2.6E-5

how would i set this up?
Draw a figures, then side opposite angle is 1 ft and horizontal is 12 ft so tan angle = 1/12.

chemistry
Convert 50.0 mL ethanol to mass using mass = volume x density. I obtained approximately 50 x 0.789 = about 40g but that's an estimate only as are all of the other numbers. You need to go through the calculations yourself. mols ethanol = 40/molar mass = about 0.87 mols O2 =...

chemistry
22% by mass means 22 g solute/100 g solution. How many mols in 22g? That's 22/342 about 0.064 mols which is an estimate as are all of the other calculations that follow. You should recalculate each for yourself. So we have 0.064g solute/100 g solution. Use the density to c...

oops--chemistry
I posted the answer then re-read the problem and saw I had not included energy to remove that 50 mL H2O at the boiling point. Therefore, I deleted that post. Here is the complete answer. energy to melt ice + energy to raise melted ice to 100 from zero C + energy to raise 100 g...

chemistry
Follow the instructions I gave. Actually there are two final temperatures and that's why I said to work the problem in steps. The FIRST final T which I've listed as Tfinal is the final T of the ice water + 100 C water. The ice melts and lowers the temperature of the 10...

chemistry
I would do this is steps. First, determine the mass of the ice. mass ice = volume ice x density ice at 0C. You will need to look up the density at 0C. Then [mass H2O x heat fusion] + [mass melted ice x specific heat H2O x (Tfinal-0)] + [mass H2O @100 x specific heat H2O x (Tfi...

Chemistry
Ptotal = pH2 + pH2O Ptotal = 99.8 kpa pH2O = 2.33 kPa. PH2 = ?

Chemistry
PV = nRT. You don't have n but n = grams/molar mass.

chemistry
I would like to know how much ice and how much liquid water @ 100 C you have? I haven't thought through the problem and that info may or may no be needed; however, it would make me feel better to have that info.

chem
1 mole of anything contains 6.02E23 molecules. Convert 19.0 g MgCl2 to mols. mol = grams/molar mass. Then convert that many mols to molecules MgCl2 (use #1 as a template if needed). Then you notice there are 3 atoms for each molecule so 3x molecules gives you atoms.

chem 2
Were are parts B, C, and D. Rxn is (add the two half cells below) Cr(s) ==> Cr^3+ + 3e Ag^+ + e ==> Ag(s) -------------------- Cr(s) + 3Ag^+ ==> 3Ag(s) + Cr^3+

chemistry
I'm guessing the reaction is something like this and I'm assuming there is enough Ag to complete the reaction although I don't know what "amount AgNO3 used was unchanged" means. Cu(s) + 2Ag^+ ==> 2Ag(s) + Cu^2+ mols Cu = grams/atomic mass mols Ag = 2 x...

Science
That isn't a good answer.

Chemistry
I agree

Chemistry
k = 0.693/t1/2 Solve for k and substitute into the below equation. ln(No/N) = kt No = 12.0 mg N = ? mg k = from above t = 13.5 hrs

Science (Please check!)
If it is a stove top burner and you set the pan on it, the heat is transferred by conduction.

Chemistry II
There is no way to answer this question without some kind of rate equation.

ALGERBRA
-7*5 = 5*91X -35 = 455X X = ?

College Algebra
That's what I would do first.

Chemistry
P1V1 = P2V2

Chemistry
http://www.jiskha.com/display.cgi?id=1401311215

Science
http://www.jiskha.com/display.cgi?id=1401311215

chemistry
Do you mean 2.10 M? If so then pOH = -log(2.10) and pH + pOH = pKw = 14 With pOH and pKw you can solve for pH.

chemistry
It COULD be right but as far as I know that is no such compound as NaHClO3. NaClO3 is sodium chlorate. HClO3 is chloric acid. I don't know of anything with the formula NaHClO3.

chemistry
I don't see a question here.

chemistry
If you say so. I don't see a question.

science
Is this a question? If so it isn't clear; please rephrase it.

Chemistry
PV = nRT n = grams/molar mass = 23.0/207 = ? Remember T must be in kelvin.

Chemistry
I know it is exothermic because I've been there and done that and I know it gets hot. You can look up delta G of products and reactants in tables and calculate delta Grxn BUT those values are based on knowing both delta H and delta S so I don't think that is a legitima...

Chemistry
It IS an exothermic reaction but I don't know that the release of CO2 is the reason. The entropy is +.

chemistry
Of course. van't Hoff factors are at best just good guesses; you might be closer to reality by picking something with i = 1; i.e., a complete non-electrolyte like ethyl alcohol or something like that.

chemistry
I think you must assume some things. 1. Since you know the solvent is water you can look up the Kf value of 1.86/mol. 2. You have your choice of solute so you can pick one that has an i = 1 or an i of some other value. 3. So 3.7 = iKm if you chose i = 2 you could pick a solute...

Chemistry
And in the "older" olden days it was amyl-propyl-ether

Chemistry
1) pH + pOH = pKw = 14. You know pH and pKw, solve for pOH. Not that hard if you can subtract. 2) I don't know where you're headed but M = mols/L or M strong acid is M of H^+ or pH = -log M.

oops --Damon--Science
I think Damon made a typo. That is kJ and not J.

chemistry
P4 ==> H3PO4 HNO3 ==> NO2

chemistry
Depends upon how much nano3 you want to make. That's the same kind of question as how many apples and how much flour are need to make an apple pie? How much ice cream is need to make a milk shake?

Chemistry HELP
AgNO3 + Cl^ --> AgCl ppts all of the Cl from NaCl and Cl from BaCl2. Na2SO4 + Ba^2+ ppts BaSO4 but leaves the NaCl intact with no reaction.

Chemistry HELP
I can get you started but you will need to fill in between the steps. Add AgNO3 to ppt all of the chloride (total chloride). Add Na2SO4 to determine barium.

Chemistry
sp1 is sigma bond single bond. sp2 is double bond; one sigma and one pi. sp3 is triple bond; one sigma and two pi.

Chemistry
Electrons in a higher energy level fall to a lower energy level; the difference in energy levels produces wavelengths of the electromagnetic spectrum. Some of that falls in the realm of visible light.

chem 11
mols NaOH = grams/molar mass = ? M = mols/L solution = ?mols/0.300 = ?

Chemistry
Ksp = (Mn^2+)(OH^-)^2 2.1E-13 = (x)(2x + 0.07)^2 To avoid a quadratic assume 2x + 0.07 = 0.07 2.1E-13 = (x)(0.0708)^2 x = (2.1E-13/(0.0708)^2 etc.

Chemistry
Use PV = nRT to caluclate mols ClF from the 343 mL value. I obtained 0.03. Use mols = grams/molar mass to determine mols UF6. I obtained 0.01. Then U + ClFn ==> UF6 + xClF .........0.03...0.01...0.03 You have 0.06 mols F in 0.01 mols UF6 (6 mols F/mol UF6) x (0.03/0.06) = 3...

Chemistry
12.0g MnI2/0.75 = ? g MnI2 to start accounting for the 75% yield = approx 16 mols MnI2 = grams/molar mass = 16/about 300 = ? Convert to mols F2. That's ? mols MnI2 x (13mols F2/2 mols MnI2) = ? x 13/2 = x mols MnI2. Convert to grams. g = mols x molar mass

Chemistry
I would convert pH to pOH first, then convert that to OH^- pH + pOH = pKw = 14 You know pH and pKw, solve for pOH, then pOH = -log(OH^-) Solve for OH^- and substitute in equations below. I obtained about 0.07M ...........Mn(OH)2 ==> Mn^2+ + 2OH^- I..........solid........0.....

Chemistry
http://chemwiki.ucdavis.edu/Physical_Chemistry/Quantum_Mechanics/Atomic_Theory/Intermolecular_Forces/Polarizability

chemistry
2HCl + X2CO3 ==> H2O + CO2 + 2XCl mols HCl = g/molar mass = 7.3/36.5 = ? M HCl = mols/dm3 = about 0.2 In the titration, mols HCl = 0.00281 x 0.2 = ? mols X2CO3 = 1/2 that from the coefficients M X2CO3 = mols X2CO3/25 = ?

chemistry
It's an endothermic reaction. It's a redox reaction. It's a decomposition type reaction but I would think thermal dissociation would fit also.

chemistry
You made a typo. O is 16 not 6. i) concn G is 0.1 mol/dm3. Calculated as follows: mols NaOH = g/molar mass = 0.1/40 = 0.025 M NaOH = 0.025/0.25 = 0.1 mol/dm3 ii)Note: 1 L = 1 dm3 and M = mols/dm3 2NaOH + H2X ==> Na2X + 2H2O mols NaOH used = M x L = 0.1M x 0.025 = 0.0025 mol...

Organic Chemistry
See 3-methyl butan-1-al See 3,3-dimethyl butan-2-one

Organic Chemistry
See benzaldye + H2 ==> http://en.wikipedia.org/wiki/Benzyl_alcohol

chemistry
Aspirin used for aches and pains and for headache. Na2CO3 used for acid stomach. Salicylic acid used for athlete's foot.

chemistry
Depends upon how much Al2O3 and/or H2 you started with.

CHEMISTRY
mols o2 gas = grams/molar mass Using the coefficients in the balanced equation, convert mols O2 gas to mols CO2 Now convert mols CO2 to grams. grams = mols CO2 x molar mass CO2 All caps makes your post difficult to read.

Calculation in chemistry
This is done the same way as the last problem with Cu and Ag. step 1. Write and balance the equation. step 2. convert grams to mols. step 3. convert mols of what you have to mols of what you want. step 4. Not asked for in this problem but if needed, then grams = mols x molar m...

Chemistry
Cu + 2AgNO3 ==> 2Ag + Cu(NO3)2 mols Cu = grams Cu/atomic mass Cu Using the coefficients in the balanced equation, convert mols Cu to mols Ag. Now convert mols Ag to grams. g = mols Ag x atomic mass Ag.

science
What's the time?

Chemistry
(P1/T1) = (P2/T2) T must be in kelvin.

Science--Myanswer Plz, plz
1, 3, 6 wrong. 7 is A.

chemistry
https://www.google.com/search?q=monomer+structure+DNA&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&channel=sb

chemistry
https://www.google.com/search?q=polymer+structure+DNA&client=firefox-a&hs=f9G&rls=org.mozilla:en-US:official&channel=sb&tbm=isch&tbo=u&source=univ&sa=X&ei=nJt_U7GKAeiqsQTh84HoCg&ved=0CDkQsAQ&biw=1143&bih=688&dpr=0.9https://www.google.com/search?q=monomer+structure+DNA&client=f...

Chemistry
IO3^- ==> I2 First balance the I so we are working with apples and apples and not apples and oranges. I on left is +10; on right is 0 add 10 e to left side 2IO3^- + 10e ==> I2 charge on left is -12; right is zero. Add H^+ to left and H2O to the right. 2IO3^- + 10e + 12H^...

chemistry
right about what? What is unsaturated?

chemistry
I don't know. Few people have the tables/graphs of solubility vs temperature memorized. If you will post the solubility from you graphs/tables I can agree or disagree with you.

Chemistry
plasma etching, wet etching, oxidation, vapor deposition, alloys, should get you started.

SCIENCE HELP !!
1. Fe can lose either two or three electrons to form iron(II) or iron(III). 2. One element loses electrons to form + ions; one element gains those electrons to form - ions.

Chemistry
nope. A is true. B. The bp is higher. C. The fp is lower D. Since B and C are not true D can't be right. "When a non-volatile solute is dissolved in a volatile solvent, three things happen. A. The vapor pressure is lowered. B. The freezing point is lowered. C. The boi...

Chemistry
What is your hang up on this question?

Chemistry
I worked this problem earlier; if you can't find it I will give you a link.

Science(chemistry) please help me fast
You should expand on this but basically the heat from the room gives energy to the molecules, they move faster and faster with increasing heat and at some point in time the molecules begin to slip and slide over and around each other and it becomes soft enough to spread.

Science(chemistry)
See your other post.

analytical chemistry
First use the Henderson-Hasselbalch equation and solve for pKa. pH = pKa + log (base)/(acid) 10.30 = pKa + log [0.4/0.2] pKa = ? mmols B initially = 0.4 x 250 = 100 mmols BH^+ initially = 0.2 x 250 = 50 ..........B + H^+ ==> BH^+ I........100...0......50 add............25.....

chemistry
Yes you would; however, you have expanded the (0.1-x)(0.1-x) unnecessarily. I would have done it this way. It's less work. Keq = (x)(x)/(0.1-x)(0.1-x) Keq = x^2/(0.1-x)^2 sqrt (Keq) = x/0.1-x and go from there.

chemistry
You need to locate the caps key on yur keyboard and use it. The concn is 1mol/10 L = 0.1M ........CO2 + H2 --> CO + H2O I.......0.1...0.1....0.....0 C.......-x....-x.....x.....x E......0.1-x..0.1-x..x.....x Substitute the E line into the K expression and solve for x, then e...

chemistry
15g of what in 2 hrs?

Chemistry
The specific heat of H2O should be listed in your text but I think it is 4.184 J/g*c. Tfinal is listed in the problem as 100 C. Tinitial is listed in the problem as 25 C. Note that if you use specific heat in J/g*c you must change q from the first part of the problem from kJ t...

Chemistry
volume coal = 7.5*7*6.5 = aprox 340 cc mass = volume x density = approx 500g but you should recalculate this number and all of the others that follow because I've estimated all of them. ?kJ = apprx 394 kJ x (500/12) = ? and it is exothermic so it has a - sign. Then +q = [m...

Chemistry
You were able to get "how far"? I don't see anything but the question and the numbers. I can work the problem for you which won't help you. If you've watched Kahn academy, what do you not understand now. Let's take it from there. How far can you get o...

Chemistry
mols N2 = 145.8g/molar mass N2 = ? Convert mols N2 to mols NH3 using the coefficients in the balanced equation. Now convert mols NH3 to g. g = mols x molar mass. This is the theoretical yield. If the actual yield is only 90%, then g NH3 x 0.90 = ?

Chemistry
See your other post.

Science 1 question
Just to add my two cents' worth, I think the question is not clearly stated. I think it makes a difference WHEN. If this is at the START of the inhalation phase you have one answer or if it is at the END of the inhalation phase you have another answer.

Science(chemistry)
physical change

Science (A&P)
https://www.google.com/search?q=food+from+mouth+to+large+intestine&client=firefox-a&hs=M6C&rls=org.mozilla:en-US:official&channel=sb&tbm=isch&tbo=u&source=univ&sa=X&ei=H_J8U_2JFPKwsATMw4CIDA&ved=0CEwQsAQ&biw=1143&bih=688&dpr=0.9

chemistry
mols HCl = M x L = ? Using the coefficients in the balanced equation, convert mols HCl to mols Mg. Now convert mols Mg to g. g = mols x atomic mass.

Chemistry
See your problem above with Mg and HCl. This is the same type of problem. The 80.5% is handled this way. 285g impure iron(II) nitrate x 0.805 = ? g pure iron(II) nitrate

Science -Check Answers-
Both are wrong.

chemistry
P1V1 = P2V2

Science(chemistry)
law of constant proportions.

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