Lab Report Water Potential Final

Lab Report: Water Potential of Plant  Tissues Aim:  To  To explore the water potentials of dierent plant tissues in dierent amounts of sucrose concentrations to deepen our understanding of osmosis. Results: Raw Data oncentrati on! mol!L length before ! cm ' "."( length after ! cm ' "."( mass before ! g ' "."+ mass after ! g ' "."+

".""

".#"

".$"

".%"

".&"

(.""

(.""

(.""

(.""

(.""

$.)*

(."#

$.)$

(.")

$.)"

$.*"

*.&"

*.+"

$.""

$.#"

#.,"

#.$"

#.""

*.""

#.&"

 Table  Table +: Personal Results Results of Apple -efore and After After ubmersion in ucrose olutions /bser0ations: 1er2 hard to cut the apples app les slices e3uall2 e 3uall2 and ma4e them the same si5e. Apple was 0er2 delicate6 multiple times a piece would be bro4en o6 so 0er2 hard to get the exact same si5e and length for each apple slice. Apple slice also had dierent widths6 could cause the2 dierence in mass. While setting on the des46 the apple lost water and 7uice. When added the apples to sucrose solutions6 apple slices 8oated. Apples added into the sucrose solutions at dierent times and dierent amounts of sucrose solution6 which could cause a dierence in results. After Af ter submersion in dierent concentrations6 some apples slices were 0er2 brown and fragile li4e in "." concentrations6 and the more the increase of concentration the more the apple became more rigid and green li4e in concentration +.". When apples la2 out on paper towel6 lost li3uid while setting. Li3uid inside of tube

felt more li3uid and clearer in the higher concentrations then the lower ones. When added meth2lene blue6 from concentrations "."9".%6 it went to the top6 at ".& sta2ed in the middle of the test tube6 and nall2 at +." it went to the bottom. Little current caused when putting needle inside solution to add in meth2lene blue and when ta4en out of test tube. Processed Data

oncentrati on! mol!L "."" ".#" ".$" ".%" ".&" +.""

length before! cm ' "."( (."" (."" (."" (."" (."" (.""

length Dierence in Die after! mass mass cm ' before! ' after! ' mass / g ' lengt "."( "."+ "."+ "."+ "."( $.)* $.*" #.," 9+.%" (."# *.&" #.$" 9+.$" $.)$ *.+" #."" 9+.+" (.") $."" *."" 9+."" $.)" $.#" #.&" 9+.$" $.)" $.$" #.)" 9+.("

 Table #: Personal Results of Apple -efore and After ubmersion in ucrose olutions with Dierence in ;ass and Length alculations: Dierence in mass< mass before9mass after Dierence in length< length before9length after  Table *: Personal Results of Percentage hange of Length and ;ass of Apple After ubmersion in ucrose olutions = change of = change mass length 9*,.#+= 9+.$"= 9*%.&$= ".$"= 9*(.$&= 9+.#"= 9#(.""= +.&"= 9**.**= 9#.""= 9*$.")= 9#.""=

alculations: = hange of mass
>raph +: Personal Results length  before / cm

Concentration ' "."( / mol/L 0.00 5.00 0.20 5.00 0.40 5.00 0.60 5.00 0.80 5.00 1.00 5.00

length after  mass / cm '  before / g

mass after/ g '

"."(

"."+

' "."+ 5.15 4.90 5.20 5.10 5.10 4.27

4.54 4.12 3.75 3.57 4.10 3.60

difference length / c

difference in mass / g ' "."+ "."(

4.96 4.85 5.06 5.20 5.16 4.90

".$# ".,* +.*+ +.%* +."% +.*"

Percentage Change of an Apple's Mass and Length in Dierent Sugar Solutions (.""= ".""= ".""R? < "."% ".(" 9(.""=

+.""

+.("

9+".""=

= change of mass Linear @= change of massA

9+(.""= Percentage Change

= change length

9#".""=

Linear @= change lengthA

9#(.""= 9*".""= 9*(.""=

R? < ".+)

9$".""= Concentration of Sugar in Solution mol/L

 Table $: Results of /ther >roup of Apple -efore and After ubmersion in ucrose olutions  Table (: /ther >roup of Percentage hange of Length and ;ass of Apple After ubmersion in ucrose olutions  change of mass

 change of length

).#(= +,.,#= *$.)*= $(.%%= #(.&(= *%.++=

*.""= 9#.""= $.""= #.""= #.""= 9+$.%"=

>raph #: /ther >roup Results

Percentage Change of an Apple's Mass and Length in Dierent Sugar Solutions (".""= $".""=

R? < ".

%$*".""= #".""=

= change of mass Linear @= change of massA = change of length

Percentage Change +".""=

Linear @= change of lengthA

".""= R? < ".*( ".""".("+.""+.(" 9+".""= 9#".""= Concentration of Sugar in Solution mol/L

/bser0ations: There is a huge dierence between personal results and those of other >roupBs results. Personal results mass and length seems to ha0e decreased compare to the other group it increased mostl2. There isnBt as a dramatic percentage change from others results compare to personal results where the range is in the 9*(=. Lastl26 percentage change in mass increases @in the positi0e region in results for other and for personal results6 the percentage change increases in the negati0e region6 so gets closer to 5ero. onclusion: As we loo4 at the results presented6 there is a 0er2 wide range of results. /n concentrating on personal results in table #6 the length seemed to ha0e decreased if we rule out the outliers @shown as CbumpsB on graph + and #6 li4e in concentration +."6 9".+". econdl26 the mass

seems to ha0e shrun4 9+.% at "." concentration6 but starts to slowl2 increase to 9+.( in +." concentration. This is somewhat similar to others results but6 the mass started b2 increasing at "." concentration getting a dierence in mass of ".$# @table $ and increases to +.* in +." concentration @with a few unexplainable bumps. This could be explained that since there was a higher concentration of water inside the cell6 than inside the sucrose solution6 water molecules transferred to the cell causing an increase in mass. This increase in mass can be shown in both graphs @+ and # represented b2 percentage change of mass. This is also 4nown as osmosis. o6 we can conclude that with an increase of concentration6 the mass and percentage change of mass will increase as well.  Though6 this conclusion was somewhat dicult with the dierence between personal results and others b2 the dierence in trends. others starts out positi0e6 where as the personal results start out negati0e6 hence a ma7or source of error in experiment. This 3uite surprised me because E was expecting results loo4ing more li4e others than m2 own6 so m2 results in a wa2 refute the idea that with increasing concentration the mass increases as well b2 starting in the negati0e region. econdl26 if we loo4 at the results of ;eth2lene -lue6 in concentrations "."9".% it rose to the top showing the solution where the stic4s were soa4ing has become denser meaning a loss of water causing it to loose its 8uidit2.  Then6 for concentration ".&6 the drop didnBt mo0e6 it sta2ed in the middle showing that the densit2 did not change hence an isotonic solution. Lastl2 at +."6 the drop san4 to the bottom showing that the solution that the apples were soa4ed in became less dense. This is caused ma2be b2 the limit of absorption of water of the cell or that the solution became more concentrated than the cell itself.  To conclude6 it seems the higher the concentration the higher the water potential within a cell becomes which is somewhat conrmed b2 the meth2lene blue6 the percentage change in mass6 and in length. F0aluation:

/ne ma7or source of error in this experiment is the inaccurac2 in measuring the slices of fruit or 0egetable6 b2 human e2e error. Got e0er2 single slice could be cut to the length of (cm6 and ha0e the same width as the others and so could se0erel2 aect the results6 which is seen in the experiment with the multiple unexplainable CbumpsB and hard to deduce when osmosis is happening. ince the apple slices were 0er2 fragile6 the2 4ept on brea4ing or crumbling6 causing another problem for all slices to be uniform. To impro0e this error6 we could ha0e more accurate e3uipment6 li4e a mechanical machine that cuts accurate slices length and width wise and tells us the exact measurements. En addition6 there couldB0e been lefto0er water or 7uice on the balance causing an inaccurac2 in mass of apple slices or the balance wasnBt set bac4 to "."g. To impro0e this error6 ma4e sure the balance is cleaned and set to "."g before measuring. econdl26 the temperature in the room wasnBt controlled6 and the le0el of osmosis can change depending on the atmosphere around it. ome solutions couldB0e been in warmer conditions causing an increase in le0el of osmosis. To impro0e this error6 we should 4eep all the solutions in a controlled en0ironment with a set temperature so no inaccurac2 will produce. Lastl26 some slices of apple were in solutions longer than others causing an extra amount of time for osmosis to happen. While others were inside the sugar solution6 others were la2ing on paper towels loosing li3uid causing a dierence in mass. To impro0e this error6 all apple slices should be ta4en out at the same time and set on a surface that does not absorb li3uid6 li4e on glass6 for a better chance in retaining the li3uid that wouldB0e been lost otherwise.