Specific Heat

<body topmargin=0 leftmargin=0 marginheight=0 marginwidth=0> <table cellpadding=0 cellspacing=0 border=0><tr> <td valign="top" colspan=2 height=90 BGCOLOR="#CC9900" TEXT="#080000" bgproperties="fixed" background="070005a0dwnjzk.png"> <div> <A HREF="lesson5.htm" TARGET="_top" TITLE="(Some) Physical Properties of Matter by "><U><B>home</B></U></A><B>     | </B><B> </B><B> </B><B>  </B><FONT SIZE="5" COLOR="#FFCC66" FACE="Arial" ><B>(Some) Physical Properties of Matter by Carl Martikean</B></FONT></div> <div> <A HREF="id32.htm" TARGET="_top" TITLE="Mass"><U><B>Mass</B></U></A><B>   |   </B><A HREF="id33.htm" TARGET="_top" TITLE="Volume"><U><B>Volume</B></U></A><B>   |   </B><A HREF="id34.htm" TARGET="_top" TITLE="Density"><U><B>Density</B></U></A><B>   |   </B><A HREF="id36.htm" TARGET="_top" TITLE="Boiling Point"><U><B>Boiling Point</B></U></A><B>   |   </B><A HREF="id35.htm" TARGET="_top" TITLE="Melting Point"><U><B>Melting Point</B></U></A><B>   |   </B><B>Specific Heat</B></div> <div> </div> </td> </tr><tr> <td valign="top" width=210 BGCOLOR="#FFFFFF" TEXT="#080000"> <div> Specific Heat</div> <bR> </td> <td valign="top" height=390 BGCOLOR="#FFFFFF" TEXT="#080000"> <div> Back to <A HREF="id22.htm" TARGET="_top" TITLE="Exercise"><U>Exercise</U></A>    Back to <A HREF="lesson5.htm" TARGET="_top" TITLE="(Some) Physical Properties of Matter by "><U>Home</U></A></div> <bR> <div> <B>Measuring the Specific Heats of Metals</B></div> <bR> <div> <B> <TABLE BORDER="2" CELLPADDING="2" CELLSPACING="1" WIDTH="741" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="ALL" ALIGN="LEFT" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=TOP HEIGHT= 1956 WIDTH="361"><div> <B>Introduction</B></div> <bR> <div> Heat is a form of energy that cannot be measured directly. However, changes in heat can be determined by measuring changes in temperature. When a substance is heated, the heat gained, <I>q, </I>depends upon three important factors; the mass, m, of the substance in grams, the specific heat of the substance, cp, and the substance's change in temperature, <FONT SIZE="3" COLOR="#000000" FACE="Symbol" >D</FONT>t. As discussed previously, to calculate the amount of heat absorbed or lost by a substance, the following equation is used:</div> <DIV ALIGN="LEFT"></DIV> <div> <B> </B>q = m X cp X <FONT SIZE="3" COLOR="#000000" FACE="Symbol" >D</FONT>t</div> <bR> <div> The specific heat of a substance is an intensive physical property, reflecting the type of bonding and intermolecular forces in the substance. In this investigation, you will measure the specific heats of several metals. First, you will need to make and calibrate a calorimeter, an instrument for measuring heat changes. You will start with a predetermined mass of water in your calorimeter. When the heated metal is added to the water, the change in temperature for the water will be measured. Using the specific heat of water (4.184 J/g C°), you will be able to calculate the amount of heat gained by the water. This value will be equal to the amount of heat lost by the metal. If the temperature change and mass of the metal are known, its specific heat can be determined.</div> <bR> <DIV ALIGN="LEFT"></DIV> <div> <B>q</B><B>metal</B><B> = q</B><B>calorimeter</B></div> <div> <B>mass</B><B>metal</B><B> X </B><FONT SIZE="3" COLOR="#000000" FACE="Symbol" ><B>D</B></FONT><B>T</B><B>metal</B><B> X C</B><B>p,metal</B><B> = </B></div> <div> <B>mass</B><B>water</B><B> X</B><FONT SIZE="3" COLOR="#000000" FACE="Symbol" ><B>D</B></FONT><B>T</B><B>water</B><B> X C</B><B>p,water</B></div> <bR> <div> <B>Calibrating the Calorimeter</B></div> <bR> <div> When carrying out calorimeter experiments, it is impossible to have perfect insulation and prevent heat from escaping. The problem of heat loss is usually solved by calibrating the calorimeter before making measurements on a system.</div> <div> When you add a known amount of hot water to a known amount of cool water in the calorimeter, the heat from the hot water will be transferred to the cool water and some heat will be lost to the surroundings. This relationship can be expressed mathematically as follows:</div> <DIV ALIGN="LEFT"></DIV> <div> <B>q</B><B>hot water </B><B>(q</B><B>cold water</B><B> + q</B><B>surroundings</B><B>)</B></div> <div> Substituting with the equation <I>q =m X</I><I> </I><I>c</I><I>p</I><I> </I><I> </I>X <FONT SIZE="3" COLOR="#000000" FACE="Symbol" >D</FONT>T for each factor above:</div> <bR> <DIV ALIGN="LEFT"></DIV> <div> <B>m</B><B>hot</B><B>(4.184 J/g C°)</B><FONT SIZE="3" COLOR="#000000" FACE="Symbol" ><B>D</B></FONT><B>T</B><B>hot </B><B>=</B></div> <div> [<B>m</B><B>cool</B><B>(4.184 J/gC°)</B><FONT SIZE="3" COLOR="#000000" FACE="Symbol" ><B>D</B></FONT><B>T</B><B>cold</B><B> +</B></div> <div> <B>m</B><B>calorimeter</B><B>(C</B><B>p</B><B>,</B><B>clorimeter</B><FONT SIZE="3" COLOR="#000000" FACE="Symbol" ><B>D</B></FONT><B>T </B>] </div> <bR> <div> Since the mass of the calorimeter and the specific heat of the calorimeter do not change, their product, <I>m x c</I><I>p </I>calorimeter<B>, </B>is a constant, which is referred to as the "heat capacity of the calorimeter," or C'. This value will be used to correct the measurements made with the metals.</div> <DIV ALIGN="LEFT"></DIV> <div> <B>m</B><B>hot</B><B>(4.184 J/g C°)</B><FONT SIZE="3" COLOR="#000000" FACE="Symbol" ><B>D</B></FONT><B>T</B><B>hot </B><B>=</B></div> <div> <B>[m</B><B>cool</B><B>(4.184 J/g C°)</B><FONT SIZE="3" COLOR="#000000" FACE="Symbol" ><B>D</B></FONT><B>T</B><B>cool</B><B> + C'</B><FONT SIZE="3" COLOR="#000000" FACE="Symbol" ><B>D</B></FONT><B>T]</B></div> <bR> <div> <B>Objectives</B></div> <bR> <div> • <B>Calibrate </B>a simple calorimeter</div> <div> • <B>Relate </B>measurements of temperature to changes in heat content</div> <div> • <B>Calculate </B>the specific heats of several metals</div> <div> • <B>Determine </B>the identity of an unknown metal</div> <div> • <B>Infer </B><B>information about </B>the strength of intermolecular forces</div> <bR> <div> <B>Materials</B></div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">2 plastic foam cups for calorimeter </div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">scissors or tools to trim cups </div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">thermometer </div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">100 mL graduated cylinder</div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">two 400 mL beakers </div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">bunsen burner or hotplate or alcohol burner</div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">large test tube</div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">balance </div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">tongs to handle hot beakers and metal </div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">metal samples (for example: iron nails, copper wires, aluminum pellets) unknown metal sample</div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">ringstand ring clamp (if using bunsen burner)</div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">wire gauze square (if using bunsen burner)</div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">test tube clamp (attaching to ringstand) </div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">boiling chips</div> </tD> <tD VALIGN=TOP WIDTH="361"><div> <B>Procedure</B></div> <bR> <div> <B>Be careful while transferring hot water. Wear goggles for safety.</B></div> <div> <B>Use caution in working with glass thermometers, </B><I><B>which</B></I><I> </I><I><B>can </B></I><B>easily shatter.</B></div> <bR> <div> 1. Make a data table like the one below in your lab notebook:</div> <bR> <div> <TABLE BORDER="2" CELLPADDING="1" CELLSPACING="1" WIDTH="321" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="ALL" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=TOP HEIGHT= 19 WIDTH="91"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="19" ALIGN="bottom" WIDTH="91" HSPACE="0" VSPACE="0"></tD> <tD VALIGN=TOP WIDTH="67"><div> Cool H<FONT SIZE="1" COLOR="#000000" FACE="Tahoma" >2</FONT>0</div> </tD> <tD VALIGN=TOP WIDTH="66"><div> Hot H<FONT SIZE="1" COLOR="#000000" FACE="Tahoma" >2</FONT>0</div> </tD> <tD VALIGN=TOP WIDTH="72"><div> Calorimeter</div> </tD> </tR> <tR> <tD VALIGN=TOP HEIGHT= 19 WIDTH="91"><div> Initial Temp.</div> </tD> <tD VALIGN=TOP WIDTH="67"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="19" ALIGN="bottom" WIDTH="67" HSPACE="0" VSPACE="0"></tD> <tD VALIGN=TOP WIDTH="66"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="19" ALIGN="bottom" WIDTH="66" HSPACE="0" VSPACE="0"></tD> <tD VALIGN=TOP WIDTH="72"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="19" ALIGN="bottom" WIDTH="72" HSPACE="0" VSPACE="0"></tD> </tR> <tR> <tD VALIGN=TOP HEIGHT= 19 WIDTH="91"><div> Final Temp.</div> </tD> <tD VALIGN=TOP WIDTH="67"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="19" ALIGN="bottom" WIDTH="67" HSPACE="0" VSPACE="0"></tD> <tD VALIGN=TOP WIDTH="66"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="19" ALIGN="bottom" WIDTH="66" HSPACE="0" VSPACE="0"></tD> <tD VALIGN=TOP WIDTH="72"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="19" ALIGN="bottom" WIDTH="72" HSPACE="0" VSPACE="0"></tD> </tR> <tR> <tD VALIGN=TOP HEIGHT= 19 ><NOBR><div> Change in Temp.</div> </NOBR></tD> <tD VALIGN=TOP WIDTH="67"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="19" ALIGN="bottom" WIDTH="67" HSPACE="0" VSPACE="0"></tD> <tD VALIGN=TOP WIDTH="66"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="19" ALIGN="bottom" WIDTH="66" HSPACE="0" VSPACE="0"></tD> <tD VALIGN=TOP WIDTH="72"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="19" ALIGN="bottom" WIDTH="72" HSPACE="0" VSPACE="0"></tD> </tR> <tR> <tD VALIGN=TOP HEIGHT= 19 WIDTH="91"><div> Volume</div> </tD> <tD VALIGN=TOP WIDTH="67"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="19" ALIGN="bottom" WIDTH="67" HSPACE="0" VSPACE="0"></tD> <tD VALIGN=TOP WIDTH="66"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="19" ALIGN="bottom" WIDTH="66" HSPACE="0" VSPACE="0"></tD> <tD VALIGN=TOP WIDTH="72"><div> (not needed)</div> </tD> </tR> <tR> <tD VALIGN=TOP HEIGHT= 19 WIDTH="91"><div> Mass</div> </tD> <tD VALIGN=TOP WIDTH="67"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="19" ALIGN="bottom" WIDTH="67" HSPACE="0" VSPACE="0"></tD> <tD VALIGN=TOP WIDTH="66"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="19" ALIGN="bottom" WIDTH="66" HSPACE="0" VSPACE="0"></tD> <tD VALIGN=TOP WIDTH="72"><div> (not needed)</div> </tD> </tR> <tR> <tD VALIGN=TOP HEIGHT= 19 WIDTH="91"><div> C'= </div> </tD> <tD VALIGN=TOP><NOBR><div> (not needed)</div> </NOBR></tD> <tD VALIGN=TOP><NOBR><div> (not  needed)</div> </NOBR></tD> <tD VALIGN=TOP WIDTH="72"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="19" ALIGN="bottom" WIDTH="72" HSPACE="0" VSPACE="0"></tD> </tR> </TABLE></div> <bR> <div> 2. Construct a calorimeter from 2 plastic foam cups. Trim the lip of one cup and use that cup for the top of the calorimeter. Make a small hole in the top so a thermometer can be inserted, as shown in Figure 3A. Place the calorimeter in one of the beakers to help prevent it from tipping over.</div> <bR> <div> 3. Put 50.0 mL of cold water in your calorimeter and allow the water to reach room temperature. Measure the temperature every minute until the temperature stays the same for three minutes. Record the volume and temperature in your data table as the initial temperature for the cool water and the calorimeter.</div> <bR> <div> 4. (Clamp the ring clamp to the ringstand if using a bunsen burner. Place the other beaker onto the wire gauze on top of the ring clamp if using a bunsen burner). Heat about 75 mL of water in the beaker to between 7080°C, using the bunsen burner or hotplate. Remove the water from the heat source and pour 50.0 mL into a graduated cylinder. Let the water sit a minute and stir to obtain a uniform temperature. Record the volume and temperature in your data table.</div> <bR> <div> 5. Immediately pour the hot water into the calorimeter with the cool water. Put on the lid and stir for 30 seconds.</div> <bR> <div> <B>Be careful not to </B><I><B>break a </B></I><B>thermometer!</B></div> <div> Record the highest temperature obtained by the mixture of hot and cool water as the final temperature for the hot water, the cool water, and the calorimeter.</div> <bR> <div> <TABLE BORDER="0" CELLPADDING="2" CELLSPACING="1" WIDTH="325" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="VOID" RULES="NONE" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=TOP ROWSPAN=4 HEIGHT= 15 ><NOBR><div> <IMG SRC="08aa2020.png" border=0 width="162" height="258" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <bR> <bR> </NOBR></tD> <tD VALIGN=TOP WIDTH="159"><div> thermometer</div> </tD> </tR> <tR> <tD VALIGN=TOP WIDTH="159"><div> hole in cup bottom for thermometer</div> <div> trim lip from this cup (calorimeter lid)</div> </tD> </tR> <tR> <tD VALIGN=TOP WIDTH="159"><div> leave lip on this cup (calorimeter base)</div> <bR> </tD> </tR> <tR> <tD VALIGN=TOP WIDTH="159"><div> beaker to keep  calorimeter from tipping over</div> </tD> </tR> </TABLE></div> <div> Figure 3A: A <B>simple calorimeter </B>can be made from two plastic foam cups with water inside.</div> <bR> <div> 6. Empty the calorimeter and make one data table like the one. below in your lab notebook for each of the metals you will be testing, including the unknown metal.</div> <bR> <div> <B>Metal Specific Heat Tests</B></div> <bR> <div> <TABLE BORDER="2" CELLPADDING="1" CELLSPACING="1" WIDTH="314" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="ALL" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=TOP HEIGHT= 19 WIDTH="106"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="19" ALIGN="bottom" WIDTH="106" HSPACE="0" VSPACE="0"></tD> <tD VALIGN=TOP WIDTH="100"><div> H<FONT SIZE="1" COLOR="#000000" FACE="Tahoma" >2</FONT>O</div> </tD> <tD VALIGN=TOP WIDTH="88"><div> Metal</div> </tD> </tR> <tR> <tD VALIGN=TOP HEIGHT= 19 WIDTH="106"><div> Initial Temp.</div> </tD> <tD VALIGN=TOP WIDTH="100"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="19" ALIGN="bottom" WIDTH="100" HSPACE="0" VSPACE="0"></tD> <tD VALIGN=TOP WIDTH="88"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="19" ALIGN="bottom" WIDTH="88" HSPACE="0" VSPACE="0"></tD> </tR> <tR> <tD VALIGN=TOP HEIGHT= 19 WIDTH="106"><div> Final Temp.</div> </tD> <tD VALIGN=TOP WIDTH="100"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="19" ALIGN="bottom" WIDTH="100" HSPACE="0" VSPACE="0"></tD> <tD VALIGN=TOP WIDTH="88"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="19" ALIGN="bottom" WIDTH="88" HSPACE="0" VSPACE="0"></tD> </tR> <tR> <tD VALIGN=TOP HEIGHT= 19 WIDTH="106"><div> Change in Temp.</div> </tD> <tD VALIGN=TOP WIDTH="100"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="19" ALIGN="bottom" WIDTH="100" HSPACE="0" VSPACE="0"></tD> <tD VALIGN=TOP WIDTH="88"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="19" ALIGN="bottom" WIDTH="88" HSPACE="0" VSPACE="0"></tD> </tR> <tR> <tD VALIGN=TOP HEIGHT= 19 WIDTH="106"><div> Mass</div> </tD> <tD VALIGN=TOP WIDTH="100"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="19" ALIGN="bottom" WIDTH="100" HSPACE="0" VSPACE="0"></tD> <tD VALIGN=TOP WIDTH="88"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="19" ALIGN="bottom" WIDTH="88" HSPACE="0" VSPACE="0"></tD> </tR> </TABLE></div> <bR> <div> 7.Put 75.0 mL of water into the calorimeter and allow it to come to room temperature. Record the mass and temperature of the water in the second data table.</div> <bR> <div> 8.Fill a 400 mL beaker with water and add some boiling chips. Use enough metal to fit into the large test tube but remain below the surface of the water when the test tube is placed into the beaker. You need to use as much metal as possible. <B>Measure the mass of the metal as precisely</B><B> </B><B>as possible before placing it in the test tube. </B>Record the mass in the data table.</div> </tD> </tR> </TABLE></B></div> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <div> <B> <TABLE BORDER="2" CELLPADDING="2" CELLSPACING="1" WIDTH="743" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="ALL" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=TOP HEIGHT= 1285 WIDTH="361"><div> 9. Clamp the test tube to the ring stand, (over the ring clamp, if using a bunsen burner) as shown in Figure 3B. Set the beaker upon the wire gauze on the ring clamp. Lower the test tube clamp so that the test tube is lowered into the beaker of water. Heat it until the water begins to boil. Allow the boiling to continue for 10 minute. You can now assume the metal is at the boiling temperature of water. Record this temperature in the second data table.</div> <bR> <div> 10.Transfer the metal to the calorimeter, holding the test tube with the clamp.</div> <bR> <div> <B>Be careful not to burn your skin with the hot water or the metal!</B></div> <bR> <div> Put the top on the calorimeter. Mix or stir for 30 seconds. Now, record the highest temperature of the water.</div> <bR> <div> 11. Repeat Steps 610 as needed for other metals, including the unknown metal.</div> <bR> <div> 12. Check with your teacher for instructions on how to dispose of your chemicals when finished. Remember to wash your hands thoroughly before leaving the laboratory.</div> <bR> <div> <B>Analysis and Interpretation</B></div> <bR> <div> 1.<B> Organizing Ideas: </B>State the scientific law that is the basis for the assumption that the heat energy lost by the metal as it cools will be equal to the heat energy gained by the water and the calorimeter.</div> <bR> <div> 2.<B> Organizing Data: </B>Using the density value given for water in Table 24 of the textbook, calculate the masses of water used in the calibration step, and record your results in the first data table.</div> <bR> <div> 3. <B>Organizing Data: </B>Finish filling out the first data table by calculating the changes in temperature involved. Using the value of 4.184 J/g C°, determine how much heat was lost by the hot water in the calibration portion of the experiment. How much heat was gained by the cool water?</div> <bR> <div> 4. <B>Inferring Conclusions: </B>Based on your answer to the previous question, how much heat was gained by the calorimeter?</div> <bR> <div> 5. <B>Organizing Data: </B>Calculate the heat capacity, C', of the calorimeter using the relationship discussed in the Introduction. Record your answer under the first data table.</div> <bR> <div> 6. <B>Inferring Relationships: </B>For the second part of the investigation, write an equation for the relationship between the heat lost by a metal, the heat gained by the water and the heat gained by the calorimeter. Solve for the specific heat of the metal by substituting the equation for specific heat (q = m X cp X <FONT SIZE="3" COLOR="#000000" FACE="Symbol" >D</FONT>T) into the first equation. Show all work for each metal. (Hint: Be sure to include the heat capacity of the calorimeter, C', in the substituted equation.)</div> <bR> </tD> <tD VALIGN=TOP WIDTH="363"><div> <B>Conclusions</B></div> <bR> <div> 1. <B>Inferring Conclusions: </B>Finish filling in the second set of data tables and use the relationship from Analysis & Interpretation #6 to calculate the specific heat of each of the metals tested.</div> <bR> <div> 2. <B>Evaluating Conclusions: </B>Compare your value for the unknown metal to the values given in Table 26 in the text. What do you think your unknown is made of?</div> <bR> <div> 3. <B>Evaluating Conclusions: </B>Compare your values for specific heats to the table values that can be found in a handbook such as the CRC <I>Handbook of </I>Chemistry <I>and Physics </I>or <I>Lange's Handbook of </I>Chemistry. (You may need to convert the values given from calories to joules to use the handbook values. The conversion factor is the same as the specific heat of water: 1 cal = 4.184 J.) Calculate your percent error.</div> <bR> <div> 4. <B>Analyzing Conclusions: </B>How do the specific heats of the metals compare to the specific heat of water? What does that imply about the amount of heat needed to heat a certain mass of metal or water to the same temperature? Which one would absorb heat better?</div> <bR> <div> 5. <B>Organizing Ideas: </B>Are higher values or lower values better for the specific heat of a calorimeter? Why?</div> <bR> <div> <B>Extensions</B></div> <bR> <div> 1. <B>Evaluating Methods: </B>Share your data with other lab groups and calculate a class average for the different specific heats of the metals. Compare the averages to the figures in a chemical handbook and calculate the percent error for the class averages.</div> <bR> <div> 2. <B>Designing Experiments: </B>What are some likely sources of imprecision in this experiment? If you can think of ways to eliminate them, ask your teacher to approve your suggestion, and run more trials.</div> <bR> <div> 3.  <B>Designing Experiments: </B>Design a different calorimeter. If your teacher approves of the design, construct it, and compare its performance to the plastic foam cups.</div> <bR> <div> 4.<B> Predicting Outcomes: </B>Predict the specific heat of glass. Name other substances that would have similar specific heats. Design an experiment to calculate the specific heat of glass beads. If your teacher approves your suggestion, perform the experiment and check your prediction.</div> <bR> <div> 5. <B>Applying Ideas: </B>How many practical applications can you think of that would relate to knowledge of a substance's specific heat?</div> <bR> <div> 6.<B> Applying Ideas: </B>Explain how the large specific heat of water is responsible for the moderating effects the oceans have on weather.</div> </tD> </tR> </TABLE></B></div> <bR> <bR> <bR> <div> <B> <TABLE BORDER="2" CELLPADDING="2" CELLSPACING="1" WIDTH="743" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="VOID" RULES="ALL" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=TOP HEIGHT= 448 ><NOBR><div> <IMG SRC="08cdebc0.jpg" border=0 width="734" height="444" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> </NOBR></tD> </tR> </TABLE></B></div> <bR> <bR> </td> </tr></table></body>