document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1131078>Question 1131078</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Reacting with water in an acidic solution at a particular&#8203; temperature, compound A decomposes into compounds B and C according to the law of uninhibited decay.  An initial amount of 0.50 M of compound A decomposes to 0.47 M in 30 minutes.  How much of compound A will remain after 2 &#8203;hours?  How long will it take until 0.10 M of compound A&#8203; remains? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #749010 by </B><A HREF=/tutors/aboutme.mpl?userid=Boreal><B>Boreal(15235)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Boreal><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=Boreal><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=749010\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A=Aoe^(kt)<BR>\n" );
document.write( "0.47=0.50e(k*0.5), using hours as units<BR>\n" );
document.write( "0.94=e^0.5k<BR>\n" );
document.write( "ln both sides<BR>\n" );
document.write( "-0.0619=0.5k<BR>\n" );
document.write( "k=-0.1238\r<BR>\n" );
document.write( "\n" );
document.write( "for 0.10 M<BR>\n" );
document.write( "0.10=0.50e^(-0.1238*t)<BR>\n" );
document.write( "0.2=e^(-0.1238t)<BR>\n" );
document.write( "-1.61=-0.1238t<BR>\n" );
document.write( "t=13.00 hours<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );