Chemical Education Today
Corrections J. Chem. Educ. 2003, 80, 40A
J. Chem. Educ. 2003, 80, 89.
The JCE Classroom Activity, Acid Raindrops Keep Fallin’ in My Lake, should have specified that low-dust or anti-dust white chalk be used. Chalk that is not labeled low-dust or anti-dust is likely to be made primarily from calcium sulfate (gypsum) rather than calcium carbonate. Colored low-dust chalk usually contains calcium carbonate, but the dyes used to color the chalk may obscure the color of the indicator (ivory low-dust chalk has been used successfully in testing). To determine if chalk of unknown composition is appropriate for use in the Activity, break off a small piece and drop it into a container with a few mL of vinegar. If bubbles form, the chalk can be used in the Activity. If there are no bubbles, the chalk does not contain calcium carbonate and will not neutralize acid in the model lake. You may wish to include calcium sulfate chalk in the Activity in addition to calcium carbonate chalk, as one of the additional solids. This could be used to begin a discussion with students about composition of chalk. Students might be interested in comparing other properties of the different chalks and attempting to discover reasons why all chalk is not the same. Low-dust chalk can usually be purchased at stores that sell educational or instructional supplies or office supplies, but is not usually available at discount stores or grocery stores. The JCE Classroom Activity Editors thank Don Lewis, a retired teacher from Texas, for bringing this to our attention. The corrected PDF is available at JCE Online as a PDF file: http://jchemed.chem.wisc.edu/Journal/Issues/2003/Jan/ PlusSub/V80N01/p40A.pdf.
In the article Rate of Reaction and Rate Equations, a part of an equation was mistakenly removed from the bottom right of p 90, adjacent to equation 6, and erroneously added to the bottom right of p 89, adjacent to equation 1. The definition for equation 6 on p 90 should read:
J. Chem. Educ. 2003, 80, 132.
and
Vicki Roth's contributions to the evaluation described in A Statistical Evaluation: Peer-led Team Learning in an Organic Chemistry Course were inadvertently attributed to Kathy Roth. The authors apologize for the error.
J. Chem. Educ. 2003, 80, 182. In the article A Novel Microscale Gas Generator, Table 1 identifies NO as “nitrous oxide”. The compound’s correct name is nitrogen monoxide or nitric oxide.
386
At constant temperature and pressure, p, the total concentration by the ideal gas equation [A] + [B] + [C] = p兾RT is a constant throughout the process, so that d[A] d[B] d[C] + + = 0 dt dt dt
(6)
The definition for equation 1 on p 89 should have this text removed: [A] + [B] + [C] = p兾RT is a constant throughout the process, so that The text on page 89, bottom right, should instead read: Rearranging
−V −1
−V −1
dNA E = L2 π σAB2 sAB[ A ][B]exp − RT dt
dnA E = Lπ σAB2 sAB[ A ][B]exp − = k[ A ][B] (1) RT dt
k being a function of T (and the nature of A and B) and identified with the rate constant. The corrected version is available at JCE Online as a PDF file at http://jchemed.chem.wisc.edu/Journal/Issues/2003/Jan/ PlusSub/V80N01/p89.pdf. The Journal regrets the error.
Journal of Chemical Education • Vol. 80 No. 4 April 2003 • JChemEd.chem.wisc.edu
