Changes of state

<body topmargin=0 leftmargin=0 marginheight=0 marginwidth=0> <table cellpadding=0 cellspacing=0 border=0 height="100%"><tr> <td valign="top" width=200 BGCOLOR="#003333" TEXT="#F7F7FF" background="03fd4c00dduajq.png"> <div> <TABLE BORDER="0" CELLPADDING="2" CELLSPACING="0" WIDTH="95" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="ALL" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=TOP HEIGHT= 46 WIDTH="91"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="46" ALIGN="bottom" WIDTH="91" HSPACE="0" VSPACE="0"></tD> </tR> </TABLE></div> <div> <A HREF="index.htm" TARGET="_top" TITLE="Science For All"><U>home</U></A></div> <div> <A HREF="site_map_and_site_search_engine.htm" TARGET="_top" TITLE="Science for all site map"><U>Site map + site search engine</U></A></div> <bR> <div> <A HREF="id56.htm" TARGET="_top" TITLE="Student pages switchboard"><U>Switchboard</U></A></div> <div> <A HREF="slg.htm" TARGET="_top" TITLE="solids, liquids and gases"><U>solids, liquids and gases</U></A></div> <div> <A HREF="slg_structure.htm" TARGET="_top" TITLE="Solids, liquids and gases their molecul"><U>Solids, liquids and gases - their 'molecular' structure</U></A></div> <div> <B><IMG BORDER="0" SRC="Symb075c00b700c8ffffff00.png" HEIGHT="13" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Changes of state</B></div> <div> <A HREF="id69.htm" TARGET="_top" TITLE="Air resistance"><U>Air resistance</U></A></div> <div> <A HREF="id79.htm" TARGET="_top" TITLE="Mass and weight"><U>Mass and weight</U></A></div> <div> <A HREF="id81.htm" TARGET="_top" TITLE="Conduction of heat"><U>Conduction of heat</U></A></div> <div> <A HREF="id92.htm" TARGET="_top" TITLE="Static Electricity"><U>Static Electricity</U></A></div> <div> <A HREF="id129.htm" TARGET="_top" TITLE="Acid Rain factfile"><U>Acid Rain factfile</U></A></div> <bR> </td> <td valign="top" BGCOLOR="#FFFFFF" TEXT="#080000" bgproperties="fixed" background="0f8a0a03.png"> <div> Changes of state</div> <bR> <div> You are visiting the Science For All site</div> <div> <B><IMG SRC="0f7f4040.png" border=0 width="500" height="4" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></div> <div> On this page you will find out about why substances melt, freeze,boil and condense. You relly need to know something about how the particles are arranged in the three states of matter. If you are not sure about that, click <A HREF="slg_structure.htm" TARGET="_top" TITLE="Solids, liquids and gases their molecul"><U>here</U></A>.</div> <bR> <div> Remember</div> <bR> <div> The easiest way to imagine particles is as small balls. <IMG SRC="12b0f0f0.png" border=0 width="15" height="15" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"> These particles are in constant movement. The <FONT SIZE="4" COLOR="#FF0033" FACE="Arial" >hotter </FONT>they are, the <FONT SIZE="4" COLOR="#FF0033" FACE="Arial" >faster </FONT>they move. </div> <bR> <div> Melting</div> <bR> <div> First of all lets get something straight. Lots of people get muddled up with <FONT SIZE="4" COLOR="#FF0000" FACE="Arial" >melting</FONT> and <FONT SIZE="4" COLOR="#FF0000" FACE="Arial" >dissolving</FONT>. Melting occurs when you <FONT SIZE="4" COLOR="#FF0000" FACE="Arial" >heat</FONT> something. Dissolving happens at any temperature - it happens when something is <FONT SIZE="4" COLOR="#FF0000" FACE="Arial" >mixed with a solvent</FONT>. </div> <bR> <div> As you <FONT SIZE="4" COLOR="#FF0000" FACE="Arial" >heat </FONT>up a solid, the particles move <FONT SIZE="4" COLOR="#FF0000" FACE="Arial" >faster</FONT> and <FONT SIZE="4" COLOR="#FF0000" FACE="Arial" >faster</FONT>. Eventually they move so fast that the individual particles of the solid move <FONT SIZE="4" COLOR="#FF0000" FACE="Arial" >away from each other</FONT> and start to move about independently in other words, they start to <FONT SIZE="4" COLOR="#FF0000" FACE="Arial" >swap places</FONT>. You know from the solids, liquids and gases pages that this is what is happening in a liquid. So, if the <FONT SIZE="4" COLOR="#FF0000" FACE="Arial" >solid </FONT>particles are now behaving like a <FONT SIZE="4" COLOR="#FF0000" FACE="Arial" >liquid</FONT>, the solid must have <FONT SIZE="4" COLOR="#FF0000" FACE="Arial" >melted</FONT>.</div> <bR> <div> Now lets get something else straight. The particles are <FONT SIZE="4" COLOR="#FF0000" FACE="Arial" >exactly the same</FONT> as they were in the solid. It is only what they are doing that changes.</div> <bR> <div> <IMG SRC="146c1670.png" border=0 width="193" height="103" ALIGN="BOTTOM" HSPACE="0" VSPACE="0">    Heating<IMG SRC="14037260.png" border=0 width="55" height="38" ALIGN="BOTTOM" HSPACE="0" VSPACE="0">   causes  <IMG SRC="13ec98e0.png" border=0 width="201" height="142" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <bR> <bR> <div> Boiling</div> <bR> <div> Continued heating will make the particles of the liquid move faster and faster. Eventually the particles will be moving <FONT SIZE="4" COLOR="#FF0000" FACE="Arial" >so fast</FONT> and so violently that they will no longer remain <FONT SIZE="4" COLOR="#FF0000" FACE="Arial" >close together</FONT>. Their movement will overcome the forces holding them together and they will <FONT SIZE="4" COLOR="#FF0000" FACE="Arial" >spread out </FONT>in all directions at high speed. Think back to the description of the movement of particles in gases - does this sound familiar? It should do, the liquid has boiled and become a gas! </div> <bR> <div> <FONT SIZE="4" COLOR="#FFCC66" FACE="Arial" >Important point again:</FONT> The particles are <FONT SIZE="4" COLOR="#FF0000" FACE="Arial" >exactly the same</FONT> as they were in the solid and the liquid. It is only what they are doing that changes.</div> <bR> <div> Science For All challenge:</div> <bR> <div> Use a computer drawing program to do a diagram that illustrates what happens to the particles of a liquid when it is heated and boils. Show how the particles were arranged before the liquid boiled and after it boiled. Describe what happens to the particles and why liquids boil using your own words. </div> <bR> <div> After you have tried the challenge, click the arrowhead below to see one possible solution:</div> <bR> <div>  <A HREF="id64.htm" TARGET="_top" TITLE="Boiling diagram"><U><IMG SRC="15232320.gif" border=0 width="50" height="50" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></A></div> </td> </tr></table></body>