Zadanie 2b
Wzorowane na: Chemistry HL Paper 3, May 2023, TZ1, pytanie 2(b). Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Informacja do zadań 2a-2b.
Five divalent metals, P, Q, R, S and T, were each placed in aqueous solutions of the sulfates of the five metals. In the table, "yes" means that a reaction occurred and "no" means that no reaction occurred.
| Metal placed in solution | PSO4(aq) | QSO4(aq) | RSO4(aq) | SSO4(aq) | TSO4(aq) |
|---|---|---|---|---|---|
| P | - | yes | no | yes | no |
| Q | no | - | no | no | no |
| R | yes | yes | - | yes | yes |
| S | no | yes | no | - | no |
| T | yes | yes | no | yes | - |
Polecenie
Sketch the voltaic cell that would produce the greatest cell potential (EMF) using the metals and solutions in this experiment. On your diagram label the metal and the solution in each half-cell, the anode, the cathode, the salt bridge and the direction of electron flow in the external circuit.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
two half-cells, each with an electrode dipping into its solution, a salt bridge dipping into both solutions, and a connecting wire «a voltmeter may be shown, a battery may not» ✔
R is the anode AND Q is the cathode «largest difference in reactivity: most reactive R, least reactive Q» ✔
the half-cell solutions are labelled RSO4(aq) with the R electrode AND QSO4(aq) with the Q electrode ✔
electrons flow through the wire from R (anode) to Q (cathode) ✔
Schemat punktowania
M1: complete circuit of two half-cells with solutions, electrodes and salt bridge; do not award M1 if a battery is included, if the liquid level is not shown, or if the electrodes or the ends of the salt bridge are not in the solutions. M2: anode and cathode correctly assigned. M3: solutions matched to the electrodes; accept a salt of R and a salt of Q even if the formula is not given. M4: direction of electron flow from the more reactive to the less reactive metal. Accept an unlabelled salt bridge.