document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=966256>Question 966256</A>: <I><SPAN STYLE=\"word-break: break-all;\"> how much pure acid do you have to add to  250 mL of an 8% acid solution to get a 20% acid solution </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #590577 by </B><A HREF=/tutors/aboutme.mpl?userid=ikleyn><B>ikleyn(52788)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ikleyn><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=ikleyn><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=590577\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <BR>\n" );
document.write( "Note that the concentrations in this problem are &nbsp;Volume-to-Volume&nbsp; concentrations, &nbsp;and they have the dimension of &nbsp;<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=mL%2FmL ALIGN=MIDDLE  ALT=\"mL%2FmL\"   DISABLED_style= \"max-width:90%; height:auto;\" > &nbsp;(i.e., actually, &nbsp;are non-dimensional).\r<BR>\n" );
document.write( "\n" );
document.write( "The amount &nbsp;(the volume)&nbsp; of pure acid in &nbsp;250 mL&nbsp; of &nbsp;8%&nbsp; acid solution is &nbsp;&nbsp;0.08*250 mL = 20 mL.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "Let &nbsp;<B>x</B>&nbsp; be the amount &nbsp;(the volume)&nbsp; of pure acid we have to add to &nbsp;250 mL&nbsp; of &nbsp;8%&nbsp; acid solution to get &nbsp;20%&nbsp; solution. \r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "Then the volume of the obtained solution will be &nbsp;(250 + x)&nbsp; mL &nbsp;and the volume of the pure acid in it will be &nbsp;(20 + x)&nbsp; mL. \r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "The concentration of the obtained solution is &nbsp;<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%2820%2Bx%29%2F%28250%2Bx%29 ALIGN=MIDDLE  ALT=\"%2820%2Bx%29%2F%28250%2Bx%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >, &nbsp;and it should be &nbsp;20%. \r<BR>\n" );
document.write( "\n" );
document.write( "It gives an equation\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%2820%2Bx%29%2F%28250%2Bx%29 ALIGN=MIDDLE  ALT=\"%2820%2Bx%29%2F%28250%2Bx%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 0.2.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "To solve it, &nbsp;multiply both sides by &nbsp;<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=250+%2B+x ALIGN=MIDDLE  ALT=\"250+%2B+x\"   DISABLED_style= \"max-width:90%; height:auto;\" >. &nbsp;You will get \r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "20 + x = 0.2*(250 + x).\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "Open the parentheses and simplify step by step:\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "20 + x = 50 + 0.2*x\r<BR>\n" );
document.write( "\n" );
document.write( "0.8*x = 50 - 20 = 30.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "Hence, &nbsp;x = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=30%2F0.8 ALIGN=MIDDLE  ALT=\"30%2F0.8\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 37.5 mL.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "<B>Answer</B>. 37.5 mL &nbsp;of pure acid should be added to &nbsp;250 mL&nbsp; of &nbsp;8%&nbsp; acid solution to get &nbsp;20%&nbsp; acid solution. \r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );