Osmosis To investigate the osmotic effects of different

Osmosis �To investigate the osmotic effects of different concentrations of sugar and salt solution �To use all the practical skills we have developed: data recording, presenting and analysing and evaluation of results �To use data to deduce the osmotic content of the cell.

Practical � You will add chips (roditas) of potato to salt and sugar solutions of different concentrations to attempt to work out the internal concentration of the potato cells. � You will work in five groups � Each group will do one concentration of salt and one of sugar: 0 M, 0. 1 M, 0. 3 M, 0. 5 M, 0. 7 M � You will collect, analyse and present class results then from these draw a conclusion.

Method � � � Weigh chips in groups of 4 and enter weight into results Table 1 Replicate x 3 Place chips in solutions (make sure you’ve recorded which solution you are using) Leave for 2 days Remove chips from solutions (do not mix them up!) Dab dry with paper and re-weigh them Record results in table Calculate change in weight and enter results in Table 1 Work out average Find out class results and complete Table 2 Note you can use the distilled water for 0 M concentrations of both sugar and salt.

Analysis �Using table 2, draw graph of change in weight vs solution concentration for salt and sugar. �Identify the concentration on both nearest to that of the potato cells �Explain how you came to this conclusion �Criticise your results using flaws in method, and reliability to evaluate how well the investigation worked.

Further evaluation �Did you recognise any differences between salt and sugar solutions? �Can you explain these? �How will you develop this investigation further? �How could you improve the data? �What other variables could you investigate? �Why may these be of interest?

Osmosis report Rubric Marks Results Analysis Evaluation Language 1 Some data collected Some effort at drawing a graph or some comment An evlautive comment Explanations very unfocused 2 Data recorded in correctly drawn tables Graph drawn and data plotted some statements made Some comments made on quality of method or data Sentences used to organise concepts 3 Full range and repetition Axes correctly chosen and TASK done Comments fully cover methods and data Concepts limited to one per paragraph 4 Tables entitled and correct units Generally well explained Some explanation of evaluation made Technical language correctly spelt 5 Accuracy of data given confidence of competent practical work Accurate explanation of findings makes full use of scientific concepts Evaluation fully explained with suggestions developing from it outlined. Comparative and connective words correctly used.