Zadanie 1c
Wzorowane na: Chemistry HL Paper 2, May 2026, TZ1, pytanie 1(c). Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Informacja do zadań 1a-1f.
Nitric acid, HNO3, is manufactured industrially from ammonia in a three-step process known as the Ostwald process.
Polecenie
The final step can be summarized as:
3 NO2(g) + H2O(l) → 2 HNO3(aq) + NO(g) ΔH⊖ = −138 kJ mol−1
(i) Sketch an energy profile for the overall reaction, indicating ΔH⊖ and the activation energy.
(ii) Describe the types of bonding found in the concentrated aqueous nitric acid product.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz CKE i punktacja
Odpowiedź z klucza
(i) exothermic profile: the products are drawn below the reactants AND ΔH⊖ (or −138 «kJ») is labelled on an arrow running down from the reactant level to the product level ✔
the curve rises from the reactants to a maximum before falling to the products AND the activation energy (Ea) is labelled on an arrow running up from the reactant level to the top of the curve ✔
(ii) covalent bonding within the NO3− ion/within HNO3 «shared pairs of electrons between N and O» OR covalent bonding between H and O within H2O ✔
ionic bonding/electrostatic attraction between H3O+ (or H+) and NO3− ions ✔
OR any named intermolecular force between named species, e.g. hydrogen bonding between H2O molecules ✔
Schemat punktowania
(i) [2] M1: exothermic profile with ΔH (or −138 kJ) labelled on an arrow from the reactants down to the products; M2: activation energy labelled on an arrow from the reactant level up to the top of the profile (a profile with no maximum cannot earn M2). Penalize incorrect arrows once only; accept double-headed arrows. (ii) [2] M1: covalent bonding, with the atoms or species concerned named (within nitrate/HNO3, or H to O within water); M2: ionic bonding between H3O+ (or H+) and NO3- ions, OR any named intermolecular force between named species. The ionic option needs the correct ion charges. Covalent bonding is required for M1; ionic bonding and an intermolecular force together do not replace it.
Komentarz
The product level must lie below the reactant level; label both the downward arrow (ΔH) and the upward arrow (activation energy).