Chemistry: All About You. Module 6. Hands on activities: Water experiments

Transcription

1 Chemistry: All Abut Yu Mdule 6. Hands n activities: Water experiments

2 CONTENTS Mdule Filtratin Slar Still challenge

3 MODULE 6. HANDS ON ACTIVITIES: WATER EXPERIMENTS In this sectin we prpse a number f hands-n activities in chemistry t increase students knwledge f chemistry cncepts and scientific prcesses. The experiments prpsed have been develped in the cntext f the Glbal Experiment f the Internatinal Year f Chemistry The Internatinal Year f Chemistry (IYC 2011) is an initiative f IUPAC, the Internatinal Unin f Pure and Applied Chemistry, and UNESCO, the United Natins Educatinal, Scientific and Cultural Organizatin. The Glbal Experiment f the Internatinal Year f Chemistry, an initiative f the IUPAC Cmmittee n Chemistry Educatin, has been develped t appeal t students frm primary schl t senir high schl. The activities that make up the experiment will help students appreciate the rle f chemistry in issues f water quality and purificatin. At the same time, students will cntribute t an nline glbal map, reprting n their investigatins f water quality and water treatment. The activities prpsed cver imprtant tpics and cnceptual understanding in science and als prvide a variety f pprtunities t learn imprtant experimental and data gathering skills. They cnsist f classrm and labratry activities t be carried ut by the teacher and his/her students. The Glbal Experiment f the Internatinal Year f Chemistry prpses experiments t test the prperties f water, filtratin materials and purificatin f water using a slar still. In these teacher guidelines, we prvide teachers with a selectin f tw examples f experiments n water that can be included in a lessn plan in cmbinatin with the vide Chemistry: All Abut Yu. The experiments have been selected by the Yung EPCA Think Tank as the best hands-n activities frm the Glbal Experiment f the Internatinal Year f Chemistry t link with the vide Chemistry: All Abut Yu. Yu can find mre lab activities n salinity and acidity f water n the website f the Glbal Experiment f the Internatinal Year f Chemistry: 2 2

4 1. FILTRATION Experiment purpse Link Pedaggical bjectives Time needed T filter water frm a natural lcal surce. Students will use husehld materials t build a water filtratin unit. 50 minutes Materials 2 litres f dirty natural water 3 litres f clean water 1 tw-litre plastic sft drink bttle with its cap 2 tw-litre plastic sft drink bttles, ne with its bttm cut ff t use as a funnel and ne with the tp cut ff t use fr sedimentatin. 1 large beaker (with a vlume f 500 ml, r 2 cups) 2 tablespns f alum 1½ cups fine sand 1½ cups carse sand 1 cup small pebbles 1 cffee filter 1 rubber band 1 large spn A clck with a secnd hand r a stpwatch Prcedure Pur dirty swamp/river/reservir water int the tw litres bttle with a cap. Place the cap n the bttle and vigrusly shake the bttle fr 30 secnds. Cntinue the aeratin prcess by puring the water int anther bttle r the beaker, then puring the water back and frth between them abut 10 times. Once aerated, gases have escaped (any bubbles shuld be gne). Pur yur aerated water int the bttle with its tp cut ff. Add tw tablespns f alum t the aerated water. Slwly stir the mixture fr 5 minutes. Allw the water t stand undisturbed in the cntainer. Observe the water at fiveminute intervals fr a ttal f 20 minutes. Cnstruct a filter frm the bttle with its bttm cut ff as fllws: 3 3

5 Prcedure Pur dirty swamp/river/reservir water int the tw litres bttle with a cap. Place the cap n the bttle and vigrusly shake the bttle fr 30 secnds. Cntinue the aeratin prcess by puring the water int anther bttle r the beaker, then puring the water back and frth between them abut 10 times. Once aerated, gases have escaped (any bubbles shuld be gne). Pur yur aerated water int the bttle with its tp cut ff. Add tw tablespns f alum t the aerated water. Slwly stir the mixture fr 5 minutes. Allw the water t stand undisturbed in the cntainer. Observe the water at fiveminute intervals fr a ttal f 20 minutes. Cnstruct a filter frm the bttle with its bttm cut ff as fllws: Attach the cffee filter t the utside neck f the bttle, using a rubber band. Turn the bttle upside dwn placing it in a beaker r cut-ff bttm f a tw litres bttle. Pur a layer f pebbles int the bttle the filter will prevent the pebbles frm falling ut f the neck. Pur the carse sand n tp f the pebbles. Pur the fine sand n tp f the carse sand. Clean the filter by slwly and carefully puring thrugh 3 litres (r mre) f clean drinking water. Thrw away the water that has passed thrugh the filter. After a large amunt f sediment has settled n the bttm f the bttle f swamp/river/reservir water, carefully withut disturbing the sediment pur the tp tw-thirds f the swamp/river/reservir water thrugh the filter. Cllect the filtered water in the beaker/plastic bttle. Cmpare the treated and untreated water. Has treatment changed the appearance and smell f the water? Outcmes fr students Scientific prcesses Observing and cmparing the appearance f untreated and treated water. Recrding the scientific data and bservatins in an apprpriate manner. Interpreting data in terms f envirnment and nature f the water invlved. Asking scientific questins abut water treatment and water in the envirnment. Carrying ut scientific investigatins by selecting and cntrlling variables. Chemistry and Physics backgrund Aeratin as a tl in water treatment the rle f xygen. Cagulatin as a chemical tl t clarify water. Sedimentatin and filtratin as physical tls t clarify water 4 4

6 2. SOLAR STILL CHALLENGE Experiment purpse Link Pedaggical bjectives Time needed Materials T clean water frm a lcal surce using a nn-cnventinal unit. Students will build a slar still and find ut hw it can purify water. 90 minutes Fr building the slar still: Large metal r plastic bwl Small, shallw glass r cup (clean) Measuring jug r cylinder Cling film (wider than the bwl) A pebble Ht water Fd dye and salt Prcedure Add a measured vlume f ht water (abut 1 cm) t the bwl. Add sme fd cluring and abut a teaspnful f salt t the water in the bwl. Take all the equipment ut t a sunny, level place. Place the glass r cup in the middle f the bwl making sure n water splashes int it. Cver the bwl lsely with cling film, sealing the film t the rim f the bwl. Place the stne in the middle f the film abve the cup. Leave the still fr at least an hur (the lnger the better) and then check that there is sme water in the cup. Take the still back indrs, remve the cling film and take ut the cup withut splashing any water int r ut f the cup. Measure the amunt f water in the cup. Observe the clur f the water in the cup and test it fr salt. Calculate the percentage f the water that was purified: 5 5

7 Outcmes fr students Scientific prcesses Observing and cmparing the appearance f untreated and treated water. Recrding the scientific data and bservatins in an apprpriate manner. Interpreting data in terms f envirnment and nature f the water invlved. Asking scientific questins abut water treatment and water in the envirnment. Carrying ut scientific investigatins by selecting and cntrlling variables. Chemistry and Physics backgrund States f matter and their inter-cnversin (evapratin and cndensatin). Distillatin as a physical tl t clarify water. The efficiency f a slar still fr purifying water. 6 6