document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=158134>Question 158134</A>This question is from textbook <A HREF=http://www.amazon.com/exec/obidos/ASIN/9780073047874/algebrahomeworkh>Organic Chemistry</A><BR>\n" );
document.write( ": <I><SPAN STYLE=\"word-break: break-all;\"> This question is actually an example problem (not explained) from a chemistry book, but I cannot remember my log rules.<BR>\n" );
document.write( "pKa = - log10 Ka<BR>\n" );
document.write( "If Ka = 1.8 * 10^-5 , then we should be able to find the pKa. (The answer is given b/c it's a sample, pKa = 4.7)<BR>\n" );
document.write( "Mathematically: x = - log10 (1.8 *10^-5)<BR>\n" );
document.write( "I don't understand what to do with the - sign in front of the log, to solve the log, one would say 10^ (1.8 * 10^-5), but then something must happen with the negative sign to give the answer of 4.7...<BR>\n" );
document.write( "Also, how do you go backwards (given pKa, solve for Ka).<BR>\n" );
document.write( "Same example: 4.7 = -log10 Ka<BR>\n" );
document.write( "so, 10 ^ x = 4.7 ?<BR>\n" );
document.write( "Then, I am lost.<BR>\n" );
document.write( "Thank you.<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #116532 by </B><A HREF=/tutors/aboutme.mpl?userid=edjones><B>edjones(8007)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=edjones><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=edjones><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=116532\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> log(1.8*10^-5)=-4.7...<BR>\n" );
document.write( "-log(1.8*10^-5)=4.7...<BR>\n" );
document.write( ".<BR>\n" );
document.write( "-4.7=log(1.8*10^-5)<BR>\n" );
document.write( "10^-4.7=10^log(1.8*10^-5)<BR>\n" );
document.write( "0.0000199526...=1.8*10-5 This is not exactly correct but you get the idea.<BR>\n" );
document.write( ".<BR>\n" );
document.write( "Ed </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );