Posts by DBob222

Total # Posts: 42

  1. Chemistry

    The two electrons of Ca are in the same orbital as the one electron from K so the distance is the same from the outside shell to the nucleus. On Ca there are 18 electrons between the two outside electrons and the inner 20+ nuclear charge so the outside electrons have a net of ...
  2. chemistry

    This is a limiting reagent problem. You know that because amounts are given for BOTH reactants. 2SO2 + O2 ==> 2SO3 mols sO2 = grams/molar mass mols O2 = 2 Using the coefficients in the balanced equation convert mols SO2 to mols SO3. Do the same for mols O2 to mols SO3. It ...
  3. Chemistry

    We will call weak acid A as HA. pH = 2.20; therefore, H^+ = 6.31E-3 ...........HA ==-> H^+ + A^- I........0.0870.....0.....0 C...........-x.......x.....x E......0.0870-x.....x......x You know x = 6.31E-3; therefore, Ka = (H^+)(A^-)/(HA) Ka = (6.31E-3)(6.31E-3)/(0.08069...
  4. math plz help

    The reciprocal of 3 is 1/3. The reciprocal of 5 is 1/5. The reciprocal of x is 1/x. The reciprocal of (x-3) is [1/(x-3)]
  5. chemistry

    This is a matter of going through each equation and determining the oxidation state of each, then comparing to see if any have changed. If not, that will answer your question. 1. Al is 0 on the left and +3 on the right. Therefore, this is an oxidation/reduction equation. etc.
  6. chemistry

    Determine moles BaCl2 = M x L. Determine moles Na2SO4 = M x L. If moles are different e can't be right. Determine the lesser quantity, that will be the limiting reagent. I should point out here that none of the answers, technically, is correct. All of the answers cite ...
  7. Chemistry

    I should have read the instructions as bob Pursley did. Would the following structures be polar or nonpolar? (Not applicable if the structure is an ion. Pick "ionic" in that case).
  8. Chemistry

    Those look ok to me. N2O is linear but polar.
  9. Chemistry

    Is the idea here for you to know the Lewis electron dot structure? Draw the Lewis structure, then determine the shape of the molecule. In order for a molecule to be polar the following two criteria must be satisfied. 1. There must be a difference in electronegativity between ...
  10. Chemistry

    There must be more to the problem than this. What is the background of the material you are studying?
  11. chemistry

    You didn't finish posting the problem.
  12. chemistry

    There are 6.022 x 10^23 atoms in a mole of atoms. number of atoms/6.022 x 10^23 = number of moles. Then moles x atomic mass element = grams of the element.
  13. Chemistry

    It all depends upon what you have in the dish. What did you have in the dish?
  14. science

    And your question is?
  15. Chemistry

    See below.
  16. Chemistry

    The scrubber reaction would have been a great one to use; however, that is out. So what about a different kind of scrubber (which isn't called a scrubber)? I think you could pick the reactions in the exhaust pipe of an automobile and how the catalyst removes NOx and SOx ...
  17. Chemistry

    0.693 is the natural log of 2. It comes from using the expression ln(No/N) = kt ln(100/50) = k*t1/2 ln 2 = k*t<sub<1/2 k = ln2/t1/2 and k = 9.693/t1/2 The No/N I used above as 100 and 50 can be any number choose as long as N is 1/2 of No.
  18. Chemistry

    There was a problem posted last night that used 150 mL benzene. Check to make sure that is not a typo. Determine mass 20.0 mL toluene. Use density to do that. Then determine mols of toluene in that 20 mL. Determine mass of benzene using density. molality toluene = mols toluene...
  19. chemistry

    The acidity of the rain is approximately 3000 times more. You can figures exactly by the following: pH = - log(H^+) 2.0 = -log(H^+) (H^+) = 1 x 10^-2 = 0.01 pH = 5.5. (H^+) = 3.16 x 10^-6 0.01/3.16E-6 = 3,164 times greater.
  20. chemistry

    No. Isn't the first column mL NaOH and the second column is pH. Then between pH 6.5 and 11.2 or so is the vertical portion of the pH and that occurs about 12 mL or so if I read your numbers correctly. A pH of 12 is at 15.0 mL and the curve in that region is almost ...
  21. chemistry

    I just can't make it look right. Sorry.
  22. chemistry

    Perhaps this one will look a little better. I quit if this one isn't better.           --------          /           | |           | |          ...
  23. chemistry

    Perhaps this one will look a little better.       &nsbp &nsbp --------           /           |           | &mbs[         | -----------------------------/
  24. chemistry

    The graph will have an S shaped curve somehting like this:     &nsbp     &nsbp-------- &nsbp     &nsbp   /         /       / ----------------/ Determine the mid-point of the curve in the middle of the sharp vertical ...
  25. chemistry

    HNO2 ==> H^+ + NO2^- Initial: (HNO2) = 0.2 (H^+) = 0 (NO2^-) = 0 Ka = (H^+)(NO2^-)/(HNO2) If 5.8% ionized, then after ionization: (H^+) = 0.2 x 0.058 = ?? (NO2^-) = 0.2 x 0.058 = ?? (HNO2) = 0.2 x (1-0.058) = ?? (Note: If soln is 5.8% ionized than unionized is 100 - 5.8 = ...
  26. Physical Science

    Light travels faster than sound.
  27. Physical Science

    The echo travels farther, doesn't it? plus it is partially absorbed by its reflector.
  28. chemistry

    Apparently your data doesn't want to copy. I assume that is what you are trying to do. How about just typing in the material. I suggest you start a new post.
  29. chemistry

    Yes, light colors reflect more heat than dark colors. Asphalt sidewalks are black, right? And that's a dark color, right?
  30. Chemistry

    I believe a city located near a large body of water is cooler than one located far from a body of water. First it takes energy to vaporize the water AND there are sea breezes and land breezes that help cool.
  31. chemistry

    Bromocresol green indicator turns from yellow in acid to blue in base. I am troubled by this question as I indicated in an answer to the same question yesterday. The mass of the lauric acid may appear in the denominator or it may appear another place depending upon how the ...
  32. chemistry

    So what's the question?
  33. chemistry

    Tell me what you don't understand about these problems. It appears obvious to me that the first one must have O2 added to it to obtain MgO. Mg + O2 ==> MgO, then balance by 2Mg + O2 ==> 2MgO The others are done the same way.
  34. Math

    approximately. about.

    combined mass products = combined mass reactants
  36. chemistry

    You (or another anonymous) asked this question a couple of days ago. The answer is the same. If CuF2 is 37.42% by mass of F, then 35.6 grams must contain 37.42% of 35.6 g. Don't forget to change percent to a decimal.
  37. chemistry

    1 mol of anything (butane for example) contains 6.02 x 10^23 anythings(molecules of butane for example). 1 mol of butane is the molar mass of butane in grams.
  38. chem

    In one of your earlier posts, you asked if this was the correct quadratic equation and it was. X^2 + 0.022X - 1.2E-4 = 0 Using the quadratic formula, which is X=(-b +/- sqrt[b^2-4ac])/2a solve for X. What is that value?
  39. chem

    I don't obtain that for an answer.
  40. math

    No. Just solve the quadratic using the quadratic formula.
  41. chem

    yes. That is the correct quadratic equation. Now solve for x. Then (H^+) = 0.01 + x and pH = -log(H^+).
  42. science

    I have 171.342 for the molar mass of Ba(OH)2 but I don't know the reliability of those values I added together. The numbers you used may be more up to date. Anyway, then 0.750 x 171.342 = 128.506 which would round to 128 to three significant figures (0.750 has three s.f...