The aim of this experiment was to investigate the effect of varying sulphuric acid concentrations on the rate of diffusion, as was indicated by the phenolphthalein colouring of the agar block. It was hypothesized that as the concentration gradient increased, so would the rate of diffusion. This prac report includes an abstract, background, aim, hypothesis, independent variable, dependent variable, control variables, safety assessment, materials, method, result, room for graphing, trend, discussion, strengths, weaknesses, random errors, systematic errors, improvements, conclusion, relevance, further research and group assessment.