Post on 18-Jan-2016
Measuring the Rate of Diffusion of Hydrochloric Acid (HCl)
through Agar Gel of different sizes
1 A Block10mm x 10mm x 10mm
Cut to produce 2 B Blocks
10mm x 5mm x 10mm
Cut to produce 4 C Blocks
10mm x 5mm x 5mm
Cut to produce 8 D Blocks
5mm x 5mm x 5mm
This diagram is on page 14 of your Handbook:
First cut 4 Agar Blocks dimensions: 10mm tall x 10mm wide x 10mm deep
1 A Block 2 B Blocks 4 C Blocks 8 D Blocks
10cm3 diluted HCl
Delay of 1 minute
Delay of 1 minute
Delay of 1 minute
START TIME 0s
Block Type A B C DStart 0min 1min 2min 3min
Finish __min__s __min__s __min__s __min__s
Total time Taken for block to change colour completely / S
sec sec sec sec
Rough work:
HCl (Acid)
SAFETYGoggles and lab coats on until I say to remove them. Long hair tied back. All bags and coats tucked under desks.
Hydrochloric Acid (HCl) and Ammonium Hydroxide (Alkali) and Creosol red dye
IRRITANTS-wash skin immediately if spillage occurs and report it to me.
Knife / Scalpel SHARP -Take care
TASKS TO DO:1.Write your group’s results onto the board.2.Copy all of the class data onto the table on p15 Handbook.3.Complete the table of calculations on p15 HB ASK FOR HELP IF YOU HAVE ANY DIFFICULTIES.4.Do the tasks found at the end of p15 HB ie GRAPH, WRITE A CONCLUSION, DESCRIBE ANY LIMITATIONS IN THIS EXPERIMENT.5. Print out the summary notes found on slides 7 and 8 from: MOODLE, Biology AS, UNIT 2, ‘Cells and Systems’, ‘Differentiation and Transport Systems’, ‘2. Surface Area to Volume ratio ppt’, just print out slides 7 & 8 only. FINISH FOR HW READY FOR NEXT LESSON.EXTENSION: Collect exam questions sheet from me and try to write answers to some of the questions on file Paper.
X
y
Surface Area / Volume RatioExpressed as a single value to 1dp.
Averagetimetaken foracid todiffuseintogel / s
= 1200= 1000= 800= 600
1000100010001000
1200:10001.2
1000:10001.0
800:10000.8
600:10000.6
6 sides of 5x5So 150mm2 per block.There are 8 blocks so:
(4 sides 10x5) + (2 sides 5x5)ie 200+50=250mm2 per blockThere are 4 blocks so:
(2 sides 10x10) + (4 sides 10x5) ie 200+200 = 400mm2 per blockThere are 2 blocks so:
6 sides of 10x10, = 6 sides of 100mm2
8 blocks4 blocks2 blocks1 block
5 x 5 x 55 x 5 x 1010 x 10 x 510 x 10 x 10
Total Volume / mm3
Surface Area/VolumeRatioAs a single value 1dp
Total Surface Area / mm2
Number of blocks of this type immersed in HCl (acid)
Dimensions of one block / mm
DCBABlock
Table to show the Relationship between Surface Area : Volume Ratio and Diffusion Rate
Block A B C D
Dimensions of one block / mm 10 x 10 x 10 10 x 10 x 5 5 x 5 x 10 5 x 5 x 5
Number of blocks of this type immersed in HCl (acid) 1 block 2 blocks 4 blocks 8 blocks
Total Volume / mm3
1000 1000 1000 1000
Total Surface Area / mm2600 800 1000 1200
Surface Area/VolumeRatio as a single value 0.6 0.8 1.0 1.2
Time Taken for blocks to all completely change colour /Seconds
Average time for diffusion (in seconds)
257 111 81 53
Table to show the Relationship between Surface Area : Volume Ratio and Diffusion Rate
Already Recorded times 257 111 81 53
X
y
Surface Area / Volume RatioExpressed as a single value to 1dp.
Averagetimetaken foracid todiffuseintogel / s
Graph to show………………………….....
X
y
Surface Area / Volume RatioExpressed as a single value to 1dp.
Averagetimetaken foracid todiffuseintogel / s
Graph to show the Relationship between the Surface Area : Volume Ratio and the Average Time for Diffusion
In this experiment the different sized jelly blocks were representing animals of different sizes with different surface areas:volume ratios.
WHAT ARE THE LIMITATIONS IN THIS INVESTIGATION?
END.
As x increases y increases at a GREATER rate
Interpreting Graphs
x
y1. 2.
x
y
As x increases y increases at a SMALLER rate
x
y
100
50
10 20
As x increases y increases at a steady rate. If x is doubled, y is doubled. We say that y is proportional to x
x
y
20
10
2 4
As x increases y decreases. It might be that if x is doubled then y is halved – in which case.. Y is inversely proportional to x
3. 4.