Essentially, random errors are caused by unknown and unpredictable changes in the experiment. These changes may occur in the measuring instruments or in the environmental conditions. This technically means that they are things/factors/events that you cannot stop from occurring.
On the other hand, systematic errors usually arise from the measuring instruments. They may occur because:
- there is something wrong with the instrument or its data handling system
- the instrument is used incorrectly by the experimenter.
Additionally, the following piece of information treats errors associated with rinsing as neither random nor systematic, but rather as student mistakes:
Student mistakes are just student mistakes; they are neither random nor systematic errors. Examples in this category are spills, misreading a device such as a burette, misinterpretation of the procedure, incorrect handling of a micro-pipettor, and forgetting to rinse out a beaker when doing a quantitative transfer. These errors are known and easily preventable, if the experiment is repeated. Systematic errors occur with each repetition of the experiment, assuming no changes in instrumentation. Mistakes should be noted in the Results section of your report as mistakes.
Of course, jazz can confirm whether the above information is accurate and whether errors associated with rinsing are considered random or systematic.
I hope this helps!