Formulate a research question, identify independent, dependent and controlled variables, and design or improve a method so that it answers the question fairly and safely.
(c) A simple set-up was used to compare the conductivity of water samples obtained from the Salton Sea at different depths. The following data were obtained: Depth water sample was obtained from / m () Electric current recorded by the…
A sample of 0.0120 mol of was placed in a sealed vessel of volume 1.00 , which was kept at a constant temperature of 35 °C. (i) Suggest a simple way of keeping the vessel at a constant temperature in a school laboratory. (ii) The…
(i) State the independent variable and the dependent variable of the investigation. (ii) Apart from the mass of leaves and the volume of water, suggest two other conditions that should be kept constant for the comparison between boiling times to be valid.
Each beaker used as a chromatography chamber was covered with a watch glass while the solvent rose up the paper. Explain why the chamber has to be covered for the experiment to be properly designed.
The student suspected that the ink contained more than four dyes, and that one of the spots was two dyes that had not separated. Suggest how the student could modify the chromatography experiment to test this idea.
Identify two controlled variables in this investigation.
The iron(II) concentration is found by titrating against a standard solution of potassium manganate(VII), . At intervals of a few days, a 20.00 sample is withdrawn from each flask and made up to 250.0 with water;…
Suggest one way of extending the investigation so that further recommendations about storing the iron(II) solution could be made.
Suggest why the times measured for equal masses of the two metals are not a valid basis for comparing their reactivity.