Measuring the Rate of Diffusion of Hydrochloric Acid (HCl) through Agar Gel of different sizes

1 A Block 10mm 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 Block2 B Blocks4 C Blocks8 D Blocks 10cm 3 diluted HCl Delay of 1 minute START TIME 0s

Block Type ABCD Start 0min1min2min3min Finish __min__s Total time Taken for block to change colour completely / S sec Rough work:

HCl (Acid)

SAFETY Goggles 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 Ratio Expressed as a single value to 1dp. Average time taken for acid to diffuse into gel / s

= 1200= 1000= 800= : : : : sides of 5x5 So 150mm 2 per block. There are 8 blocks so: (4 sides 10x5) + (2 sides 5x5) ie = 250mm 2 per block There are 4 blocks so: (2 sides 10x10) + (4 sides 10x5) ie = 400mm 2 per block There are 2 blocks so: 6 sides of 10x10, = 6 sides of 100mm 2 8 blocks4 blocks2 blocks1 block 5 x 5 x 55 x 5 x 1010 x 10 x 510 x 10 x 10 Total Volume / mm 3 Surface Area/Volume Ratio As a single value 1dp Total Surface Area / mm 2 Number of blocks of this type immersed in HCl (acid) Dimensions of one block / mm DCBA Block Table to show the Relationship between Surface Area : Volume Ratio and Diffusion Rate

Block ABCD Dimensions of one block / mm 10 x 10 x 1010 x 10 x 55 x 5 x 105 x 5 x 5 Number of blocks of this type immersed in HCl (acid) 1 block2 blocks4 blocks8 blocks Total Volume / mm Total Surface Area / mm Surface Area/Volume Ratio as a single value Time Taken for blocks to all completely change colour /Seconds Average time for diffusion (in seconds) Table to show the Relationship between Surface Area : Volume Ratio and Diffusion Rate Already Recorded times

X y Surface Area / Volume Ratio Expressed as a single value to 1dp. Average time taken for acid to diffuse into gel / s Graph to show………………………….....

X y Surface Area / Volume Ratio Expressed as a single value to 1dp. Average time taken for acid to diffuse into gel / 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 y x y As x increases y increases at a SMALLER rate x y 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 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.