Zadanie 2a
Identify two controlled variables in this investigation.
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Identify two controlled variables in this investigation.
The iron(II) concentration is found by titrating against a standard solution of potassium manganate(VII), KMnO4. At intervals of a few days, a 20.00 cm3 sample is withdrawn from each flask and made up to 250.0 cm3 with water;…
The following readings are recorded during one titration. Final burette reading = 23.20 ± 0.05 cm3 Initial burette reading = 3.20 ± 0.05 cm3 Calculate the percentage uncertainty in the volume of KMnO4 solution delivered…
The student's results are shown in the graph. (i) Calculate the average rate at which the iron(II) concentration fell in the 24 h flask during the 21 days. Include units. (ii) Before starting, the student proposed the hypothesis: "The longer a solution is left…
Suggest one way of extending the investigation so that further recommendations about storing the iron(II) solution could be made.
In the Geiger–Marsden experiment, α-particles (the nuclei of helium-4 atoms) were fired at a very thin foil of silver. A detector that could be moved around the foil recorded the angle of deflection, θ, of the particles. Two of the possible routes are shown:…
Lithium can be identified in the light emitted by stars and by flames containing lithium compounds. (i) Outline the appearance of the emission spectrum of lithium. The emission spectrum of a one-electron species, such as the Li2+ ion, can be explained…
Outline why the scientific model of the atom has been modified several times since it was first proposed.
Which electron transition in a hydrogen atom emits radiation with the longest wavelength? A. n = 2 to n = 1 B. n = 3 to n = 2 C. n = 4 to n = 3 D. n = 1 to n = 4
Sketch, on the axes, the graphs of the time for complete reaction against the mass of metal that you would expect for sodium and for potassium. Label each line.