Zadanie 6a
Wzorowane na: Chemistry HL Paper 2, May 2023, TZ1, pytanie 6(a). Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Polecenie
Hydrogen sulfide, H2S, is removed from natural gas by burning it in air to form sulfur dioxide.
(i) Determine the standard enthalpy change of reaction, ΔH⊖, in kJ mol−1, for 2 H2S(g) + 3 O2(g) → 2 SO2(g) + 2 H2O(l), using the data given.
| Substance | ΔHf⊖ / kJ mol−1 |
|---|---|
| H2S(g) | -20.6 |
| SO2(g) | -296.8 |
| H2O(l) | -285.8 |
(ii) Formulate equations showing how sulfur dioxide and carbon dioxide each make rainwater acidic.
(iii) Explain the polarity of the S-Cl bond in sulfur dichloride, SCl2. Use section 9 of the data booklet.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
(i) «ΔH⊖ = ΣΔHf⊖(products) − ΣΔHf⊖(reactants)»
[2 × (−296.8) + 2 × (−285.8)] − [2 × (−20.6) + 0] = −1124.0 kJ mol−1 ✔
(ii) SO2(g) + H2O(l) → H2SO3(aq) AND CO2(g) + H2O(l) ⇌ H2CO3(aq) ✔
(iii) «electronegativity» Cl = 3.2 and S = 2.6, so Cl is the more electronegative atom / there is a difference of 0.6 ✔
the bonding pair is drawn towards Cl, so Cl is partially negative (δ−) and S is partially positive (δ+) ✔
Schemat punktowania
(i) [1]. (ii) [1]: both equations needed; accept a single arrow for the carbon dioxide equation and accept equations that show H+ (or H3O+) with HSO3− and HCO3−. State symbols are ignored. (iii) [2]: M1 the electronegativity values or difference from section 9; M2 the direction of polarity with partial charges. Accept a suitable diagram showing the S-Cl dipole.