Saturday
March 28, 2015

Posts by DrBob222


Total # Posts: 47,990

SCIENCE
q needed = [mass gasoline x specific heat gasoline x (Tfinal-Tinitial) Substitute and solve for q.
March 6, 2015

organic chemistry
Sorry but I can't help.
March 6, 2015

chemistry
Draw the lewis structure of NF3 and not the lone pair. Draw the NF4^+ and note the absence of a lone pair. You may be more familiar with drawing NH3 vs NH4^+.
March 6, 2015

chemistry--Tulane University
A = ebc A= 4700*1*1.oE-4 A = ?
March 6, 2015

Science
Basically one object has excess electrons. You can read more about it here. http://en.wikipedia.org/wiki/Static_electricity
March 6, 2015

Chemistry
Use the Henderson-Hasselbalch equation. This is a buffer solution.
March 6, 2015

Chemistry
Use the Henderson-Hasselbalch equation
March 6, 2015

chemistry
I don't understand the trouble you're having. Qsp is just the ion product as if it were Ksp; then you can compare with Ksp and see if the Ksp is exceeded. If so a ppt forms, if not there is no ppt.
March 6, 2015

Chemistry
The point of this problem is to illustrate that when all are gases one may use a shortcut in which L is used as if L were mols. So using the coefficients in the balanced equation to convert L of one substance to L of any other. I assume you can balance the equation.
March 6, 2015

Chemistry
mols LiClO4 = grams/molar mass = ? Use the coefficients in the balanced equation to convert mols LiClO4 to mols O2. Now convert mols O2 to L at the conditions listed. Use PV = nRT for that. Beware of units. If you use P in kPa, you must use R = 8.314. If you use P in ...
March 6, 2015

chemistry
..........Ag3PO4 ==> 3Ag^+ + PO4^3- I.........solid.......0.......0 C.........solid.......3x......x E.........solid.......3x.......x Substitute the E line into Ksp expression and solve for x = molar solubility
March 6, 2015

Chemistry
C shortest B longer A none
March 6, 2015

chemistry
I don't understand the problem. Please rephrase it and if you have an equation include that. That phrase "of 7.00 g NH3 of 9.00g of NO" is the confusing part. It doesn't make sense.
March 5, 2015

Chemistry
All three are based on the fact that 1 grams equivalent weight is deposited with 96,485 coulombs a). You can deposit 107.9 g Ag metal with 96,485 coulombs, Coulombs = amperes x seconds
March 5, 2015

a note:--Chemistry
Ka1 is relatively large; probably you will need to solve the quadratic for Ka1.
March 5, 2015

Chemistry
What about looking at the three Ka values seprately? You notice that they are about 10^5 from each other. That means that the (H^+) is determined primarily by the first ionization. The second and third ionization produce little H^+. So do the first calculation as you would a ...
March 5, 2015

Chemistry
Tell me what you don't understand about this.
March 5, 2015

Science
It was Po.
March 5, 2015

Science
yes. Do you know what that element was?
March 5, 2015

Science
I don't agree with A.
March 5, 2015

chemistry
Use PV = nRT to calculate pressure of each gas. n = grams/molar mass Then Ptotal = pO2 + pHe
March 5, 2015

Energy&Society
This may help. http://www.comfortsystems.ws/WhatsNew/Fuel%20cost%20comparision%20information.pdf
March 5, 2015

chemistry
A. mols acetone = M x L = ? B. 5.00 M x (10 mL/total volume)= ? C. final (I2) = 0.005M x (10 mL/total volume) = ?. Then rate rxn = final (I2)/400 D. repeat of C. You should be able to use these numbers to do part B yourself.
March 5, 2015

Chemistry
I think the question is "last of all how can I calculate the molar mass?). HA + KOH ==> KA + H2O mols KOH = M x L = ? mols HA = mols KOH since the ratio of the coefficients is 1:1. Then mols HA = grams HA/molar mass HA. You have grams and mols, solve for molar mass.
March 5, 2015

chemistry
(V1/T1) = (V2/T2) Since they don't give a volume, just make up a convenient number for V1(say 100 L) then V2 will be 113 L.
March 5, 2015

chemistry
You need to know if this is psia or psig. If psia you can use P1V1 = P2V2 diectly. In the absence of anything in the problem that tells you, I would assume psia.
March 5, 2015

CHEMISTRY!!!!
What is it that you don't understand about the problem? The pH at the equivalence point of formic acid and NaOH is determined by the hydrolysis of the salt, i.e., sodium formate.
March 5, 2015

chimestry
What do you not understand about this? The pH is that of a salt of a strong base/strong acid.
March 5, 2015

Inorganic Chemistry
SF6 for sure. http://en.wikipedia.org/wiki/Point_reflection#Inversion_with_respect_to_the_origin
March 5, 2015

chemistry
(V1/T1) = (V2/T2) Don't forget T must be in kelvin.
March 5, 2015

using skills
I agree with choice c, also, but frankly I don't think much of the answers. In my opinion all of the answer are true (well, maybe B is not that true). I liken these answers to walking in a mine field and you're having to choose between quite similar answers to come up ...
March 5, 2015

using skills
What does your book say. "According to the text," tells me the answer is in your text.
March 5, 2015

Chemistry
Write and balance the equation. mols HBr = M x L = ? mols NaOH = M x L = ? Which reactant is in excess. If HBr, the pH = -log(HBr) If NaOH, the pOH = -log(NaOH) and pH + pOH = pKw = 14.
March 5, 2015

chem
Use the dilution formula mL1 x M1 = mL2 x M2
March 5, 2015

chemistry
See your other post.
March 5, 2015

chemistry
Generally, there are three reasons why a reaction will occur. 1. A gas is formed. You need to know those gases. H2, N2, O2, Cl2, plus usual compounds like CO2, CH4, acetylene (C2H2), NO2, and a few others. 2. A precipitate (an insoluble compound) is formed. You need to know ...
March 5, 2015

chemistry 12u
I don't see a question here. Also I think you have a typo in the equation.
March 5, 2015

Ap chemistry
I'll be happy to help. Tell me exactly what you don't understand about the question. Do you know what Q is? Do you know what equilibrium is?
March 5, 2015

CHEMISTRY
Write and balance the equation. Using the coefficients in the balanced equation, convert mols I2 to mols AgI Now convert mols AgI to grams AgI. grams AgI = mols AgI x molar mass AgI.
March 5, 2015

Science
Those look ok to me IF you made a typo on #3 and it should read and electric motor instead of electric meter.
March 4, 2015

Science
Evaporation of water cools the wet bulb.
March 4, 2015

chemistry
Convert g each to mols and convert to XCS2 Then psolution = XCS2*Po CS2 Post your work if you get stuck and I can help you through it.
March 4, 2015

Chemistry
http://www.ausetute.com.au/metallic.html
March 4, 2015

CHEMISTRY
THANK YOU for showing your work. I can tell at a glance that your work is right and the process is right. My only comment is that if your prof is picky about the number of significant figures s/he may not concur with an answer with that many places.
March 4, 2015

Chemistry
Also you can use the Henderson-Hasselbalch equation which is a little easier to handle.
March 4, 2015

Chemistry
ln(No/N) = kt No = 100 N = 89 t = 62 min solve for k. Then k = 0693/t1/2
March 4, 2015

Chemistry
What do you know about this? Show your work of what you have done. Explain fully what you don't understand.
March 4, 2015

CHEMISTRY
What do you not understand about this?
March 4, 2015

Chemistry
It's all done with mL1 x M1 = mL2 x M2 Substitute the numbers and you have it.
March 4, 2015

Chemistry Dr. Bob222
I don't know why the delay in discussing/asking questions about limiting reagents but then I'm not teaching the course. To recap, I think you had 2.02g NaHCO3 and 0.77 g citric acid (or was that 0.76 g). To determine the LR reagent and the theoretical yield, I do these...
March 4, 2015

Chemistry
q = mass H2O x heat vaporization
March 4, 2015

Chemistry
Just use the dilution formula. Substitute and turn the crank. mL1 x concn1 = mL2 x concn2
March 4, 2015

Chemistry
OH is 2x Ba(OH)2. pOH = -log(OH^-)
March 4, 2015

Chemistry
I don't necessarily agree with your description. NaN3 dissociates to Na^+ ad N3^-. The N3^- hydrolyzes in solution to HN3. Can you write and balance the equation for the hydrolysis of the azide ion. Where do you get stuck from there?
March 4, 2015

chemistry
How much of the solution? mols needed = M x L = ? Then grams = mols x molar mass
March 4, 2015

Chem - solubility
Can you write the ICE chart and Ksp equation? Show what you can do and explain where you have problems.
March 4, 2015

Chem
What do you not understand about the problem? This is Le Chatelier's Principle in action.
March 4, 2015

Chemistry Dr. Bob222
I think I must have answered this elsewhere.
March 4, 2015

Chemistry
Six problems in one post. What do you not understand about this. I can help you through it if I know where to start. Show what you know to do.
March 4, 2015

chemistry
I can't read this post.
March 3, 2015

chemistry
q = -15.3 kJ/mol x (18.8/molar mass KC2H3O2) = approx - 3.03 kJ or 3030 J. Then -3030 = mass H2O x specific heat H2O x Tfinal-Tinitial) Substitute the numbers and solve for Tfinal
March 3, 2015

Chemistry Dr. Bob222
You know I know how to calculate the TY and AY and %Y now, but I'm confused on the finding limiting reactant? umm Let me see if I can figure it out and you let me know if I'm on the right track... 2.02g NaHCO3 mols = 2.02/84 = 0.0240 mols the ratio is 3/1 for ...
March 3, 2015

Chemistry Dr. Bob
. Show that the equivalence amount of citric acid for 2.00 g of sodium bicarbonate is 1.52 g. *** 1 mol citric acid reacts with 3 mols sodium bicarbonate, molar mass NaHCO3=84g/mol 2 moles in 2 g? = 2/84? = 0.0238 mols 2g NaHCO3? then to find the citric acid? is it.. 0.0238/3...
March 3, 2015

chemistry
Like charges repel; unlike charges attract.
March 3, 2015

chemistry
Wouldn't you expect it to get stronger (as long as the electron is in the same shell).
March 3, 2015

Chemistry Ap
We can't draw diagrams on this forum but it is easy to see if I could draw a graph. Basically this is what you do. XH2O = Pomethanol-Ptotal/(Pomethanol-PoH2O) That gives you (89.0-35.5)/(89.0 - 17.5) = 0.748 for H2O I can never remember the formula; I draw it out with a ...
March 3, 2015

chemistry
I agree Good work.
March 3, 2015

chemistry
I see. I do all of the typing so you can check your values. How about us turning that around. You do the typing (show me what you have or tell me what you don't understand) and let me check your results. You have the right equation, the right products, and it's ...
March 3, 2015

chemistry
This looks simple enough. What do you not understand? Acid + base = salt + H2O
March 3, 2015

Chemistry
12. Negative charge must equal positive charge since all elements are neutral.
March 3, 2015

AP CHEM LAB
mols HCl = M x L = ? mols NaOH = mols HCl (since there is 1 mol HCl reacting with 1 mol NaOH) Then M NaOH = mols NaOH/L NaOH. You know mols and M, solve for L NaOH.
March 3, 2015

Chemistry
Atomic masses are average masses of the different isotopes of that element that occur naturally. For example, the mass of Cl-35 and the mass of Cl-37 are averaged (about 76% for 35 and 24% for 37) and the weighted average is about 35.5 for naturally occurring Cl2.
March 3, 2015

Chemistry Dr. Bob
You did the 1 g NaHCO3 vs 0.76 g citric acid (as you posted earlier) correctly. For #2 you use YOUR numbers. mols in 1g NaHCO3 = 1.02/84 = about 0.012 Convert to mols CO2. That's approx 0.012 x 1 mol CO2/1 mol NaHCO3 = about 0.012 mols CO2. Convert to grams CO2. 0.012 mol ...
March 3, 2015

chemistry
1 for Cu in the ground state. 5 are in the valence shell of As.
March 3, 2015

Chemistry
The first ionization energy (first IP) generally increases as one moves from the left to the right on the periodic table (in the same period). That's because the nuclear charge in increasing but the added electrons are going into the same shell so the attractive force is ...
March 3, 2015

chemistry
Those intermolecular forces add up to extra holding power; therefore, it is harder to break the bonds from a liquid to a vapor state. That means more energy must be transferred to the liquid and that means a higher boiling point.
March 3, 2015

chemistry
NH4I(s) + H2O(l) ==> NH4^+(aq) + I^-(aq)
March 3, 2015

Chemistry
You would expect the boiling point to be higher for H2O than for H2S because of hydrogen bonding in H2O. The problem didn't ask about boiling point, you say? Yes it did. It asks for volatility, that is vapor pressure, and that leads to boiling point.
March 3, 2015

Chemistry Dr. Bob
I answered below at the first post and I don't agree with your calculations. You never had 1g CO2 did you?
March 3, 2015

Chemistry
There are shorter ways to do this but they are harder to explain. I do them the long way this way. mols N2 = grams/molar mass = ? mols Mg = grams/molar mass = ? Using the coefficients in the balanced equation, convert mols N2 to mols Mg3N2. Do the same for mols Mg to mols ...
March 3, 2015

Chemistry
I told you how to do it. You could try following my instructions. Here is how you do the sodium propionate. You want 1 L of 0.1M CH3CH2COONa mols needed = M x L = 0.1 M x 1 L = 0.1 mol Then mol = grams/molar mass 0.1 mol = grams/96 grams = 96 x 0.1 = 9.6 grams. Place 9.6 g the...
March 3, 2015

Chemistry
I don't buy any of this. The numbers, even if they are right, (and they may be), are not realistic. Who would want to make 0.01 mL of such a solution? That's about two drops. :-)
March 3, 2015

Chemistry
The way I read the question is that there are two questions; i.e., 1. How to prepare 0.1M solution of propionic acid and 2. How to prepare 0.1M solution of the salt. 1. Since no volume is given you just assume some volume you want to prepare. 1L is the easiest to assume ...
March 3, 2015

Chem Dr. Bob Plz
mols in 1g NaHCO3 = 1/84 = ? mols CO2 produced = same or 1/84 grams CO2 = mols x molar mass = theoretical yield. You're right that mols CO2 = 1g/molar mass CO2 IF YOU HAD 1 g CO2 but you didn't. You said you had 1 g NaHCO3; furthermore, you calculated the mass CO2 as 0...
March 3, 2015

Chemistry
Use PV = nRT Remember T must be in kelin. V is in L.P in atm.
March 3, 2015

Chemistry
Yes it has 5 valence electrons. But aren't those bonding electrons? The question is for non-bonding electrons.
March 3, 2015

Science 8th Grade
I don't agree with your answer. Why not use some numbers and see what happens. For example, E = 100, I = 50; R = ?. Then E = 100 and I = 50; R = ?. The general rule is E = IR so R = E/I. If I is constant than R = E*(1/k); therefore, if E goes up then R goes up. If E goes ...
March 3, 2015

Chemistry
I have the same answer and that will be ok. If your prof is picky about significant figures s/he may have issue depending upon the numbers you used to make that calculation.
March 3, 2015

Chemistry
Is that your answer? The molar mass N2O was not the question.
March 3, 2015

Chemistry
[(2*atomic mass N/molar mass O2)]*100 = ?
March 3, 2015

pharmacy tech
You need to know what kind of percent it is; i.e., % by mass(w/w), % w/v or % v/v. If % w/v for example, that is mass [(solute/mL solution)]*100 = % If it is a 5% w/v solution that is 5 g solute in 100 mL solution and you want to know grams in 50 mL, that is (x/50)*100 = 5 (x/...
March 3, 2015

Chemistry (organic)
Do you have a K. I usually use them as g/g and if your prof does the same, then Ko/a = K(16.9/9.5) = 1.78 Then K = (concn organic phase/concn aqueous phase). Let x = g in organic phase, then 5-x = g in aqueous phase. For org phase you have x/100 For aqueous phase you have (5-x...
March 3, 2015

chemistry
C'mon. Use that caps key when needed. PbO + CO ==> Pb + CO2 Use PV = nRT and solve for n = number of mols for CO at room T. T will be 298 K if you use 25C as room T. V will be 2400 and P will be 1 atm. Then convert mols CO to mols PbO using the coefficients in the ...
March 3, 2015

chemistry
What temperature? what pressure? Is that at STP? What Pb; i.e., PbO or PbO2. IF at STP, then mols CO = 2400 cm3/22.4 dm3 = ? But I can't even write an equation with know the kind of lead oxide.
March 3, 2015

chemistry help fast
1. Convert 16 tonnes of Fe2O3 to grams. 2. Convert g Fe2O3 to mols. mols = grams/molar mass 3. Using the coefficients in the balanced equationk convert mols Fe2o3 o mols CO. 4. Convert mols CO to grams. grams CO = mols CO x molar mass CO
March 3, 2015

Chemistry
I worked this for you last night and added an addendum to it this morning. I assume you've not looked for it. If you have some questions about it or the solution to it, repost it along with whatever solution and/or questions you have.
March 3, 2015

chemistry help
That is CO2, not Co2. CO is carbon monoxide. Co2 is diatomic cobalt. CO2 + C ==> 2CO mols CO2 = grams/molar mass = ? Using the coefficients in the balanced equation, convert mols CO2 to mols CO Now convert mols CO to grams CO. g CO = mols CO x molar mass CO
March 3, 2015

Chemistry Help
If H3O^+ > 10-7M, acid If H3O^+ = 10^-7M, neutral If H3O^+ < 10^-7M, basic
March 3, 2015

more on #1--Chemistry Help
(H3O^+)(OH^-) = Kw = 1E-14. You know Kw and H3O^+, solve for OH^-
March 3, 2015

Chemistry Help
You would do well to post separate posts. Sometimes we don't have time to answer 4-5 questions at a time. Calculate the concentration of OH− and the pH value of an aqueous solution in which [H3O+] is 0.014M at 25°C. Is this solution acidic, basic or neutral? pH...
March 3, 2015

Pages: <<Prev | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | Next>>

Members