Reliability = the reproducibility of experimental results, or in the case of research, it refers to the credentials of the sources you've used to complete the assignment + if the information gathered is correct
- Approach this by saying how multiple TRUSTED sources (such as university websites, educational websites etc) have all given similar information regarding ethanol etc (ie. cross-referencing)
Accuracy = how close the value YOU obtained is to the theoretical value for experimental results (depends on the calibration of your apparatus, such as a thermometer or scale), or in the case of research, if the information you've obtained is correct
- Similar to reliability, approach this by saying how multiple websites have given similar information (again, cross-referencing)
Validity = how appropriate the method used in your experimental procedure is towards fulfilling the aim of the experiment, or in the case of research, if the source you've used gives you the information needed to complete the assignment
- Approach this by saying how a particular source helped you with a particular part of your assignment (eg. "Source" provided me with information on how ethanol is industrially produced, which is required of the assignment)
However, make sure to check with your teachers as to what they're expecting for reliability, validity, accuracy.
Hope this helps, good luck in your studies!