Question

the experiment you undertook to test one of the factors that affects diffusion of a solute in a solvent: Parameter chosen: Null hypothesis: Alternate hypothesis: Dependent variable: Independent variable: Controlled variables: Write a detailed protocol on how you would perform the experiment and measure the results. You can use dot points to detail the steps taken to perform the experiment – make sure you mention all details of the materials you use so that anyone reading these instructions could repeat the experiment and would get the same results. Experimental protocol

Answer 1

Parameter chosen : Temperature

Null Hypothesis : Temperature will not have any effect on the diffusion of solute in a solvent.

Alternate Hypothesis : Temperature will have a signficant effect on the diffusion of a solute in a solvent.

Dependent variable : Solute concentration

Independent variable :Temperature

Controlled variable : Time, Volume of solvent, Pressure.

Experiment Protocol :

1. Take 2 beakers of equal volume .

2. Take Beaker 1 as control and Beaker 2 as experimental.

3. Dissolve NaCl in both of them.

4. Place Beaker 2 under a Bunsen burner and light it.

5. Measure salt concentration at every 5 mins interval till 20 mins using an Electrical Conductivity Meter.

6. Note down the salt concentrations.

7. Repeat the experiment for another two times to get a good collection of data.

Analysis :

1. Take the data collected and subject it to a Paired t-test.

2. For carrying out Paired t-Test, we first need to calculate the difference (di) between the two observations on each pair (For eg - Salt concentration at 5 mins for control group - Salt concentration at 5 mins for experimental group).

3. We will thus get 4 di values. Now we have to take a mean of these values dmean.

4. Now we will calculate the standard deviation of these di values and then sum them to get the standard deviation .(S.D.)

5. Calculate Standard Error (S.E.) by using the formula = S.D. / (n)1/2 where n = number of sets of observations. (here n = 4)

6. Calculate t - statistic value using the formula : t = dmean / S.E.

7. Calculate degree of freedom ( dF) = n - 1.

8. Now take the table of t-distribution and note down the value of t at obtained degree of freedom at 0.05 level of significance.

9. Compare the values of t which you calculated and with the chart value.

10. If the obtained t- value is greater than that of the chart value, then the Null hypothesis can be rejected . Otherwise it is accepted.