Simple chemical reactions

<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="y7_materials.htm" TARGET="_top" TITLE="Y7 switchboard"><U><IMG SRC="14a32320.gif" border=0 width="50" height="50" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></A> <A HREF="y7_materials.htm" TARGET="_top" TITLE="Y7 switchboard"><U>Y7 switchboard</U></A></div> <div> <A HREF="id22.htm" TARGET="_top" TITLE="Y7 Natural and synthetic materials "><U>Y7 Natural and synthetic materials </U></A></div> <div> <A HREF="id38.htm" TARGET="_top" TITLE="Y7 dissolving"><U>Y7 dissolving</U></A></div> <div> <A HREF="springs.htm" TARGET="_top" TITLE="Y7 Stretching"><U>Y7 Stretching</U></A></div> <div> <A HREF="id78.htm" TARGET="_top" TITLE="Y7 mass and weight"><U>Y7 mass and weight</U></A></div> <div> <A HREF="id80.htm" TARGET="_top" TITLE="Y7 Fossil fuels"><U>Y7 Fossil fuels</U></A></div> <div> <A HREF="id85.htm" TARGET="_top" TITLE="Y7 Adaptations to winter"><U>Y7 Adaptations to winter</U></A></div> <div> <B><IMG BORDER="0" SRC="Symb075c00b700c8ffffff00.png" HEIGHT="13" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Simple chemical reactions</B></div> <bR> </td> <td valign="top" BGCOLOR="#FFFFFF" TEXT="#080000" bgproperties="fixed" background="05379803.png"> <div> Teacher Pages</div> <bR> <div> You are visiting the Science For All site</div> <bR> <div> <IMG SRC="0613d050.png" border=0 width="573" height="5" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <div> How do we recognise chemical reactions?</div> <bR> <div> <I><B>Aims:</B></I><B> </B><I>By the end of this lesson, pupils should be able to recognise a variety of ways in which chemical change can be recognised by utilising their observation and reasoning skills. Pupils will also need to use teamwork skills in order to complete the work in one lesson. </I></div> <bR> <div> <I><B>Outcomes: </B></I><I>Pupils should have completed the worksheet and have generalised that the following are indicators of a chemical reaction:</I></div> <div> <I>Unexpected colour changes</I></div> <div> <I>The appearance of materials that were not there initially</I></div> <div> <I>Changes in temperature without refrigeration or heating</I></div> <div> <I>effervescence </I></div> <div> <I>Also, pupils should be led to generalise that effervescence indicates that a gas  (i.e. a new material) is formed in the reaction.</I></div> <bR> <div> <I><B>Language for learning: </B></I><I>Spellings of words like temperature and chemical can be reinforced. New words like exothermic, endothermic, effervescence and evolution (plus derivatives) can be defined. If time allows, the words reactants and products could also be introduced. Reference should be made to the terms "reversible changes" and "irreversible changes" that should have been taught at KS2.</I></div> <bR> <div> <I><B>Needs: </B></I></div> <div> <I>Copper carbonate powder</I></div> <div> <I>0.1M nitric and sulphuric acids</I></div> <div> <I>0.1M sodium hydroxide</I></div> <div> <I>250ml pyrex beakers</I></div> <div> <I>Spatulas</I></div> <div> <I>Thermometers</I></div> <div> <I>Small pieces of the following metals - lead, zinc, magnesium, calcium</I></div> <div> <I>Forceps</I></div> <div> <I>Droppers</I></div> <div> <I>10ml measuring cylinders</I></div> <div> <I>Newspaper</I></div> <div> <I>Test tubes and racks</I></div> <div> <I>Cloths</I></div> <div> <I>0.5M ethanoic acid</I></div> <div> <I>Ammonium carbonate powder</I></div> <div> <I>Safety goggles</I></div> <div> <I>Photocopied "Recognising chemical reactions" worksheet</I></div> <div> <I> <a href="HTMLobj-582/recognising_reactions.doc"><img align="bottom" border="0" width="55" height="22" alt="Recognising reactions worksheet" src="HTMLobj-582/pencil.GIF"> <u>Recognising reactions worksheet</u></a>  </I></div> <bR> <div> <I>RISK ASSESSMENT:</I></div> <bR> <div> <I>This is obviously your responsibility but here are some of my observations.</I></div> <bR> <div> <I>The chemicals are harmful, irritants and corrosive. Pupils should be made aware of the dangers to skin and eyes. Safety goggles should be worn throughout the experiment and clearing up afterwards. The waste should be collected in a bucket or other suitable container. Appropriate warning should be given in connection with the acid + calcium reaction - it generally leaves the tube as it effervesces, hence the newspaper. Small pieces of calcium should be used and handled using forceps. I usually personally place the Ca into a </I><I><B>DRY</B></I><I> test tube for the pupils who can then transport it safely to their workplace and tip it into the tube containing the acid. The use of droppers can reduce the hazard when handling the solutions. </I></div> <bR> <div> <I><B>Intro:</B></I><I> Establish by questioning the level of knowledge amongst the pupils. Utilise this to introduce the new language. Write the keywords on the board/OHP so the spellings are visible during the discussion. Hand out the worksheet and explain the aims of the lesson. Check these by asking some of the weaker pupils to reiterate them for the benefit of the class. (Timing: 5-8 mins).</I></div> <bR> <div> <I><B>Activity:</B></I><I> The only way that this can be completed in one lesson is if teamwork is employed. Pupils will need to organise themselves so that 2 pairs work as a team. One pair can work on experiments 1 and 3 whilst a second pair works on 2 and 4. With very slow groups, teams could consist of three or even four pairs if necessary. They then share results. I find that this works best if a separate section of the lesson is allocated to this - I generally make a fuss about sharing results during the clearing away time (this also has a benefit of absorbing the staggered finish from the pupils who are slow!) (Timing 20 min + 10 for clearing up and sharing results)</I></div> <bR> <div> <I>Activity: Individually complete the conclusion section of the sheet then after 2-3 min, pupils compare notes and add/delete points as necessary. (Timing about 5-7 mins)</I></div> <bR> <div> <I><B>Close:</B></I><I> Take input from class as to how they would recognise a chemical reaction. Ask them to justify what they are saying. Reinforce the new vocabulary.</I></div> <bR> <div> <I><B>Assessment: </B></I><I>From the closing session and from marking of the worksheets. These should indicate if further work on this aspect of the topic is needed. </I></div> </td> </tr></table></body>