Posts by DrBob222

Total # Posts: 55,605

Chemistry
Ca(OH)2 ==> Ca^2+ + 2OH^- SO, if [Ca(OH)2] = 0.0027 M then (OH^-) must be twice that. Right?

Chemistry
pH = -log (H3O^+) and since HCl is a strong acid and ionizes 100%, then pH = -log(HCl). In very weak acid solutions it is necessary to take into account the H^+ contribution of the H^+ in water but I don't think that will be necessary in this concentration.

Chemistry
Set up Kp expression. You know Kp and pCS2. Solve for pS2 at equilibrium. Remember not to include C(s) in the expression. Kp = 5.6 - pCS2/pS2

Chemistry
Go to this site and read the assumptions. https://en.wikipedia.org/wiki/Kinetic_theory_of_gases

chemistry
I need to know the solubility of KNO3 at 50 C and 40 C. You must have a table or a graph that gives you this information.

Chemistry
mols K3PO4 = grams/molar mass = ? mols H3PO4 used in the reaction is 1 mol H3PO4 used for every 1 mol K3PO4 produced (look at the coefficients). grams H3PO4 to start = trams used + grams remaining

Chemistry
See your other post.

Chemistry
You can figures these out if you remember that a beta particle has a -1 charge and a mass number of 0 and you think about it. In radioactive reactions the subscripts must add up and the superscripts must add up. Here is an example. It's difficult to write subscripts and ...

chemistry
The problem states that the 100 g C is an excess; therefore, this is not a limiting reagent problem, assuming that statement is correct. Therefore, it's worked as a simple stoichiometry problem.

Chemistry
All look true to me except for C.

Chemistry
Zn ==> Zn^2+ + 2e is the strongest reducing agent (easiest to oxidize). 2H2O ==> O2 + 4e + 4H^+ is the weakest reducing agent, hardest to oxidize.

Chemistry
I don't see a reaction.

Chemistry
See my first line. Not only did I tell you that you needed coulombs but I told you how to calculate it. coulombs = A x seconds. amperes in the problem = 2.00 A. time in the problem = 19.0 min or 19.0 x (60 seconds/min) = ? seconds so coulombs = 2.00 x 19.0 x 60 = >

Chemistry
coulombs - A x seconds = ? 096,485 coulombs will deposit 63.55/2 g Cu = approx 32 but you need a better number than that. Then 32? x coulombs/96,485 = g Cu deposited.

CHECK my answers Physical science
I don't agree with any of your answers.

Chemistry
coulomhs = A x seconds = about 7,200. 96,485 coulombs will plate out, in grams, atomic mass Gd/#e = 157.25 g/#e. grams Gd plated = 0.025 x 157.25 = about 3.93 grams. atomic mass Gd/#e x 7,200/96,485 = 3.93 Solve for #e and I would round to the nearest whole number. My guess, ...

Chemistry
coulombs = A x secnds = ? Cr probably in the +3 state so 96,500 coulombs will deposit atomic mass/3 g Cr (about 52/3 = 17). Then 17 x (coulombs,96,500) = ? g Cr.

Chemistry
I didn't check the math on the calculator but the process and the numbers are correct.

Science
Organic chemist, pharmacy to develop new drugs, certainly forensics, med tech in hospital or similar setting, teaching, water analysis for organic pollutants, and a host of others. I know a number of MDs who didn't like the "beside manner" requirements and they ...

Chemistry
right

Chemistry
See my response under your other post where you used the Cee name. If I know it, and I usually do, I am starting a new "me" by not answering questions posted by ad nauseam number of screen names.

chemistry
First off, please don't change screen names. It confuses us and you don't get answers as fast as you may wish. CHEMICAL properties are those which take place with a chemical reaction. If something different (a different substance) is formed, that is a chemical property...

Chemistry
Please don't change screen names. Lucy, John Butch, etc won't cut it. We can help better if we can keep one name. For the Bi half, Bi on the left has an oxidation number of +3 and on the right is 0 so that is a gain of 3e and the 3e goes on the right. That's how ...

chemistry
See your other posts. Please help us help you better by keeping the same screen name. See my response under Lucy.

more info---Chem
This info isn't made obvious in most chem classes and isn't prominent in texts so here is a tid bit of info that may prove useful to you. permanganate (MnO4)^- goes to manganate (MnO4)^2-in basic solution, to MnO2 is neutral or near neutral solution and to Mn^2+ in ...

Chem
Adam, please see the responses to Lucy, John Butch, etc. Your mistake here is that you are balancing the reaction in acidic solution. MnO4^- goes to MnO4^2- in basic solution. You seem to be OK with these so I'll leave that with you but if you have trouble, please re-post ...

Chem
It's on the reactant side but it isn't 4. If you'll post your half cell reactions I'll find the error.

Chemistry
mols Fe(NO3)3 = M x L = ? Use the coefficients in the balanced equation to convert mols Fe(NO3)3 to mols K2C2O4. Then M K2C2O4 = mols K2C2O4/L K2C2O4. You know mols and M, solve for L and convert to mL if needed. Post your work if you get stuck.

Chemistry
First, your rationale is OK about energy and wavelength. You KNOW the answer can't be c or d because the atom ABSORBS energy to do that. Atoms EMIT energy only when they go from a higher level to a lower level. So that leaves a or b as the only possibilities so you can ...

Chemistry
95% by mass ethanol means 95 g ethanol in 100 g total. 100 g total-5g ethanol = 95 g H2O. mols ethanol = grams/molar mass = ? mols H2O = grams/molar mass total mols = mols ethanol + mols H2O Xethanol = mol ethanol/total mols. Post your work if you get stuck.

Chemistry
No. Oxidation is the loss of electrons; reduction is the gain of electrons. Your equation is not right to begin with. It shows a reduction half but NOT an exidation half. I suspect you intended to write CO2(s) + H2(g) ==> CO(g) + H2O(g) Start by assigning oxidations numbers...

Chemistry
The question asks for the NET ionic equation. What you have written (correctly) is the MOLECULAR equation. To turn the molecular equation into the net ionic equation you cancel ions common to both sides. That means 2Na^+ and 2HCO3^- cancel leaving Pb^2+(aq) + S^2-(aq) ==> ...

Chemistry
Use the coefficients to convert mols of what you have to mols of what you want. 2 mols O3 x (1 mol NO2/1 mol O3) = 2 x 1/1 = 2 mols NO2. Now convert mols NO2 to grams. Grams = mols NO2 x molar mass NO2 = ?

Chemistry
You're right

Chemistry
That is exactly right. That problem set a trap and you fell for it. The GRAMS of H in a 20 g sample will be different than the grams in a 10 g sample but the % stays the same.

Chemistry
No. The answer isn't 1/2 of 11.19 either. Your guessing. If you have 5g apples and 5g oranges (10 g total), percent apples is ?. If you have 100g apples and 100g oranges (200 g total), percent apples is ? If you have 25g apples and 25g oranges(50 g total), percent apples ...

Chemistry
No. The answer is NOT twice 11.19.

Chemistry
OK but because Li is smaller size.

Chemistry
For M2S3, that means S is -2 and M is +3. Hint: O is in the same column as oxygen.

CHM
dE - q _ w w = -340 J dE = 8450 J Solve for q. q = mass gas x specific heat x (Tfinal-Tinitial) Substitute and solve for specific heat.

Chemistry
The way I see it is that HI doesn't share an electron between H 1s and I 5p. Rather, HI is a strong acid, it ionizes completely and I look at it as an ionic compound in which the 1s electron from H is transferred to the 5p5 (to make 5p6 and that with the 5s2 makes 8 ...

physical science
Not through a vacuum but any solid, liquid, gas.

Chemistry
CS2 + 3Cl2 => CCl4 + S2Cl2. mols Cl2 = grams/molar mass = ? Convert mols Cl2 to mols CS2 using the coefficients in the balanced equation. Then grams CS2 = mols CS2 x molar mass CS2. Post your work if you get stuck.

Chemistry
If a is the edge length of the cell, then 4r = 1.414*a Solve for a, then volume = a^3.

Chemistry
right. It is not.

Chemistry 212
#1 is that I think you are using the wrong equation. Although you didn't define your symbols, I think the equation should be t = ln(No/Nt)/k where No is what we start with (100) and Nt is what we end up with (100-61.7 - 38.3) and k is 0.004278 using your formula (which is ...

Chimie, Sciences,Effets inductifs
I presume this is organic chemistry. You can best read about inductive effects by searching on google. The inductive effect is caused largely by highly electronegative atoms such as F and Cl.

chemistry
Interesting student. I don't aee a question. Try to post your questions without theatrics please. The line AUTOMATICALLY moves to the next line. You need not hit the enter button after every one or two.

chemistry
Your method of posting makes it difficult to read. Also, you don't ask a question but if you want to know how much is the final volume use the dilution formula. mL1 x M1 - mL2 x M2 55 x 2.80 = mL2 x 2.00

chemistry
I looked for, but could not find, anything on Google that gave an answer to your question. I did find this site that gives some info on how to set up MO bonds. Perhaps it will help you get started. https://www.chem.fsu.edu/chemlab/chm1046course/motheory.html

science
First, what experiment have you done? Second, are you looking for someone to write your paper for you. We're not inclined to do that.

word problem
C = # children A = # adults ---------------- A + C = 312 9.00A + 3.50C = 1884 Solve these two equations simultaneously for A and C. Post your work if you get stuck.

Chemistry
Check your work. I found 9.52. I used 9.26 for pKa. 14-4.74 = 9.26

Chemistry
See your other post. NH is the base. Remember to change Kb to pKa.

Chemistry
Close but I wouldn't round it off to 4.7.

Chemistry
Use the Henderson-Hasselbalch equation. the salt is the base.

Chemistry 212
Yes, that is right if yu use it correctly. To use it, just substitute 100 for Ao and 50 for A and solve for t which then will be t1/2 Actually it doesn't matter what number you pick for Ao as long as A is 1/2 that. Another way and slightly shorter is to tkae ln 1/2 (which ...

science
It would be nice to know what layers b and d are.

Physical Science
Total R. 1/R = 1/R1 + 1/R2 + 1/R3 Then I = E/R

Chemistry
mols CoBr2 = grams/molar mass = ? Then m - mols/kg solvent.

Chemistry
% = grams solute/100 g solution

Science
https://www.nrdc.org/stories/global-warming-101

Spelling
unspry as in can't get around very well

chemistry
Every four hours means 6 in a 24 hr period so 6 x 10 = 60 mg.

Chemistry
I don't understand the question the way it's worded.

Chemistry
Call CH3COONa = NaAc and HAc is acetic acid; i.e., CHCOOH. It's the Ac^- that is hydrolyzed. .......Ac^- + HOH ==> HAc + OH^- I....0.08..............0.....0 C......-x..............x.....x E....0.08-x............x.....x Kb for Ac^- = (Kw/Ka for HAc) = (x)(x)/(0.08-x). ...

Chemistry
24 C doesn't sound very cold to me.

CHEMISTY
If we knew the molarity you wanted for the buffer we could calculate it. I suppose not knowing the M you must make it up and measure. So I would take 10 mL of the acetate stock and 10 mL of the acid stock, mix, and add drop wise and with stirring, NaOH until the pH meter reads...

Chemistry
I didn't check out our equation but I don't get that answer. INstread I plugged your answer in to see if it would plate out 1.27 grams, as follows: Coulombs = 0.002528 x 20 x 60 = approx 3 coulombs. 96,485 coulombs will plat out 63.55/2 = 31.775 g Cu so 31.775 x about ...

science
The answer isn't 1. The posts are spaced 2.5 m apart so between the 5th and 15th post there are 9 spaces of 2.5 m each. 9*2.5 - 22.5 m. distance = rate x time. 22.5 = rate x 2.5 seconds. Solve for rate (velocity).

Science
I didn't look up the link Ms. Sue gave but I lived there for almost 60 years. The one nearest me was the Atchafalya Basin. Try pronouncing that name. https://en.wikipedia.org/wiki/Atchafalaya_Basin

SCIENCE CHEMISTRY
And what other information do you have available. You must have some way to calculate atomic masses of O and H. Or is it OK to look those up on the periodic chart.

SCIENCE CHEMISTRY
Please use the same screen name. We halp better if you do that.

Science
And you don't have a clue? Look up the answers for a definition of each

science
Now if we knew what atoms were in area a, b, c, and d we might be able to help you.

bonding types of compounds
I am not impressed with any of the choices but a seems to be the best. By the way, you will get more help and faster help if you tell what you don't understand about your question. Just posting a question and expecting us to answer each and every one is not the way we like...

Science
I agree with resistor.

chemical reactions
a is not true. b is not true. c is confusing to me. d is your best best I think.

Chemistry
.....PtS ==> Pt^2+ + S^2- I....solid....0......0 C....solid....x......x E....solid....x......s Ksp = (Pt^2+)(S^2-) You know Ksp, substitutethe E line into the Ksp expression and solve for x = solubility in mols/L. Convert mols/L to grams/L with grams = mols x molar mass...

chemistry
Unless you have experimental evidence for the value, most of the time we assume it is 1. Often that is far misleading.

Chemistry
E = q + w 117J = -40.1J + (-20.3 J) This doesn't add to 117; I don't understand the problem. Perhaps another tutor can help.

Intermediate Maths
mass = volume x density mass = 2,500 mL x 0.64 g/mL = ?

Chemistry
yes

ap chemistry
Is go nitrogen a different kind of nitrogen? N2 + 2O2 ==> 2NO2

Chemistry
The correct answer is D. https://www.google.com/search?q=percent+fat+in+daily+diet&ie=utf-8&oe=utf-8 To explain further about the cereal box in my pantry, 60 g fat at 9 calories/grams is 540 calories. 540 calories on a 2000 calorie/day diet is (540/2000)*100 = about 27%. D is ...

Chemistry
I agree with your answer to 1 but not two. My cereal box says total fat should not exceed 60 g for 2000 calorie/day diet. That makes your answer look skimpy to me. Note; A gram of fat is about 9 calories; you can work out the percent from that..

Opinion Ques
I agree with Ms. Sue

chemistry
To bad you didn't show how you got that number. I could have looked at it and found the problem. mols CuBr2 = gams/molar mass = ? Then M = mols/0.5L = ?

Chemistry
The HCl was standardized with what? You have NaCO3 and that can't be. Is it NaHCO3 or Na2CO3. If Na2CO3 I must know what was used for the indicator.

chem
You don't need the temperature but you do need Keq unless, as I suspect, the author of the problem wants us to assume that the decomposition is COMPLETE. If that's the case, it is done this way. .......N2H4 ==> N2 + 2H2 I......800......0.....0 C.....-800......800......

Chemistry
k = -.693/t1/2</sub Solve for k, then ln(No/N) = kt. No = 2.40 N = solve for this You know k from above. t = 120 months.

Chemistry
pH = 11.12. Convert to pOH. pH + pOH = pKw = 14 so pOH must be 14-11.12 = 2.88 Convert to OH^- pH = -log(OH^-) (OH^-) = about 0.0012 but that's just a close estimate. You should redo that estimate for a better answer. .......NH3 + HOH ==> NH4^+ + OH^- I......0.1...

Chemistry
In calories. heat lost by 16.2 g steam @ 100 C to condense to liquid is q1 = mass x heat condensation. q1 = 16.2 x 540 cal/g = ? q2 = heat lost with H2O liquid moving from 100 C to 0C. q2 = mass H2O x specific heat x (Tfinal-Tinitial) = 16.2 g x 1 cal/g*C x 100 C = ? Total ...

chemistry
ln(No/N) = kt (c) part. Let No = 100 to start. then N = 50 at end. ln(100/50) = 2.2E-5*t 0.693 = 2.2E-5*t and t = about 30,000 hours but that's just a close estimate. You should get a better answer. Post your work if you have problems.

Chemistry
Your equation isn't balanced and is incorrect. Its diprotic because it has two H atoms that ionize. molecular equations are H2SO3 ==> H^+ + HSO3^- and HSO3^- ==> H^+ + SO3^2- but I think the question is asking just for the first one to show it gives H3O^+. The net ...

Chemistry
See your post below.

Chemistry
Ecell = (-0.0592/2)log Q You know Ecell is 0.024 v Q from the equation you wrote is (?Zn^2+)/(Zn^2+ 0.1) or it may be better to write Q as Q = (x/0.1) and solve for x = ?M Zn^2+ on the right hand side of the equation. Post your work if you get stuck.

math URGENT HELPPPP!
http://mathworld.wolfram.com/TriangularPyramid.html

Chemistry
Just convert grams Mg to mols Mg and you have it. g Mg/min = 1.5/3.0 = 0.5 g Mg/min or 0.5 g/24.3 = approx 0.02 mol Mg/min. or convert at the beginning but it's more work. 6.00/24.3 = approx 0.25 mols Mg initially. 4.50/24.3 = approx 0.19 mols final. (delta mols Mg) = ...

Chemistry
Your 0.5 mol HCl needed and 18.25 g needed are correct but it's the long way of going about it. However, you have no connection between this work and the 37 g/100 that you have in the stock. You can complete your work by mass = volume x density or 18.25 = volume x 1.19 or ...

  1. Pages:
  2. <<Prev
  3. 3
  4. 4
  5. 5
  6. 6
  7. 7
  8. 8
  9. 9
  10. 10
  11. 11
  12. 12
  13. 13
  14. 14
  15. 15
  16. 16
  17. 17
  18. Next>>