6. Enthalpy is a measure of total energy in a thermodynamicsystem. The following table presents enthalpy measurements on 16water based systems. Four measurements are made on each of foursystems which differ by concentration of NaCl (table salt).
Concentration (%) | | Enthalpy | | |
5 | 1.62 | 1.60 | 1.62 | 1.66 |
10 | 2.69 | 2.66 | 2.72 | 2.73 |
20 | 3.56 | 3.45 | 3.65 | 3.52 |
30 | 3.35 | 3.18 | 3.40 | 3.06 |
- What pairs of concentrations, if any, can you conclude to havediffering enthalpies? Use α = 0.05.
  | 5-10 | -1.07 | 10-5 | 1.07 | 20-5 | 1.92 | 30-5 | 1.62 |
5-20 | -1.92 | 10-20 | -0.85 | 20-10 | 0.85 | 30-20 | 0.55 |
5-30 | -1.62 | 10-30 | -0.55 | 20-30 | 0.30 | 30-10 | -0.30 |
All concentrations are significant atthe 0.05 level. WHY?
- Compute the quantity s = (MSE)0.5, the estimate ofthe standard deviation σ.
- Assuming s to be the error standard deviation, find the samplesize necessary in each treatment to provide a power of 0.80 todetect a maximum difference of 0.1 in the treatment means at the 5%level.
