validity question (1 Viewer)

[wogga]

I was trying to answer some past questions on shipwrecks, and l got stuck on this one.

During your practical work you performed a first hand investigation to compare and describe the rate of the corrosion of iron in different acidic and neutral solutions.

i. Outline the conclusion drawn from the results of this task and assess the validity of these conclusion. (3)

I know the first part is faster corrosion will occur in the acidic solution...but the second part l don't get.

Our school never asks validity questions in exams so l don't really understand it. Plus l don't think l did this practical properly because our teacher said we did this at the maritime musuem.
l know you're meant to justify the method or something along those lines...any help would be appreciated

 

[danz90]

Even though I didn't do this option, I can tell you about validity.

Validity encompasses the idea that the dependent variable is solely influenced or determined by the independent variable in the investigation, i.e. a method is reached so that only one conclusion is always reached by adopting the one procedure.
To 'validate' an experiment, you must control all variables that may affect the dependent variable (eg temperature, pressure, pH etc etc) EXCEPT the independent variable, which you obviously change to observe its effect on the dependent variable.
Also, you must have a control experiment (where the independent variable is absent, hence ALL variables are controlled) to make valid comparisons in order to reach a valid conclusion.

Hope that helps.