Assign oxidation states to atoms in compounds and ions using the standard rules, including hydrogen as -1 in metal hydrides and oxygen as -1 in peroxides, write them with the sign first (+2, -1) and explain why an uncombined element has oxidation state zero.
Tę umiejętność sprawdza 28 zadań wzorowanych na arkuszach IB z lat 2022–2026.
An ‘iodine clock’ experiment can be based on two reactions that occur at the same time. S2O82−(aq) + 2 I−(aq) → 2 SO42−(aq) + I2(aq) slow 2 S2O32−(aq) + I2(aq) → S4O62−(aq) + 2 I−(aq) fast The iodine formed in the slow reaction is removed at…
Propane undergoes complete combustion. C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(g) (i) Calculate the enthalpy change of reaction, ΔH, in kJ mol−1, for the combustion of propane. Use section 12 of the data booklet. (ii) State the…
What happens to hydrogen in the following reaction? Each option states whether hydrogen is oxidized or reduced and the change in its oxidation state. Mg(s) + 2 HCl(aq) → MgCl2(aq) + H2(g) A. Oxidized, from +1 to 0 B. Oxidized, from 0 to +1 C. Reduced,…
What is the oxidation state of chlorine in Cl2O7? A. −7 B. +3.5 C. +7 D. +14
In which species does an atom have the oxidation state +5? I. IF5 II. H3PO4 III. N2O4 A. I and II only B. I and III only C. II and III only D. I, II and III
Sulfur has different oxidation states in hydrogen sulfide, H2S, and in sulfurous acid, H2SO3. Which pair of values is correct? A. H2S: +2; H2SO3: +4 B. H2S: −2; H2SO3: +6 C. H2S: −2; H2SO3: +4 D.…
In which compound does nitrogen have an oxidation state of +3? A. NH3 B. HNO2 C. NO2 D. HNO3
Sulfur dioxide can also be removed from flue gas by reaction with hydrogen peroxide, forming sulfuric acid. SO2(g) + H2O2(aq) → H2SO4(aq) Deduce which element is reduced in this process, indicating the initial and final oxidation states.
Methanoic acid, HCOOH(aq), and hydrochloric acid, HCl(aq), are both acids. A 0.100 mol dm−3 solution of HCOOH(aq) has a pH of 2.39 while a solution of HCl(aq) of the same concentration has a pH of 1.00. (i) Explain…
What are the oxidation states of the elements in K2MnO4? A. K: +1, Mn: +6, O: −2 B. K: +1, Mn: +7, O: −2 C. K: +2, Mn: +4, O: −2 D. K: +1, Mn: +6, O: −1
Which row identifies the oxidizing agent and the reducing agent in the reaction below? 3 Cu(s) + 2 NO3−(aq) + 8 H+(aq) → 3 Cu2+(aq) + 2 NO(g) + 4 H2O(l) A. Oxidizing agent: Cu, reducing agent: NO3− B. Oxidizing agent: NO3−, reducing…
Calcium hydride is used as a portable source of hydrogen for fuel cells. It reacts with water as shown. CaH2(s) + 2 H2O(l) → Ca(OH)2(aq) + 2 H2(g) Which statement is correct? A. Calcium is reduced from +2 to 0. B. Hydrogen in CaH2 is oxidized from…
(i) State the oxidation states of carbon in carbon monoxide and in carbonyl chloride. (ii) For each of CO and Cl2 in the forward reaction, state whether it acts as an oxidizing agent or a reducing agent, and whether it is oxidized or reduced.
Potassium permanganate reacts with potassium iodide in alkaline solution. 6 MnO4−(aq) + I−(aq) + 6 OH−(aq) → 6 MnO42−(aq) + IO3−(aq) + 3 H2O(l) Identify the species oxidized and the number of electrons transferred in the equation as written.
In which reaction does N2 act as a reducing agent? A. N2(g) + 3 H2(g) → 2 NH3(g) B. 3 Mg(s) + N2(g) → Mg3N2(s) C. N2(g) + O2(g) → 2 NO(g) D. 6 Li(s) + N2(g) → 2 Li3N(s)
(i) Identify the oxidation state of metal S in SSO4. (ii) Deduce the order of reactivity of the five metals, from the most reactive to the least reactive.
State the oxidation state of manganese in the permanganate ion, MnO4−.
Which change involves the oxidation of chlorine? A. Cl2 → Cl− B. ClO4− → ClO3− C. Cl2 → ClO3− D. HCl → Cl−
Which element has more than one oxidation state in its compounds? A. Sodium B. Magnesium C. Fluorine D. Sulfur
Which species could be reduced to form elemental sulfur, S? A. H2S B. ZnS C. SO2 D. CS2
Determine the oxidation state of iodine in the iodate ion, IO3−.
Determine the oxidation state of carbon in methanol, CH3OH.
In which compound does manganese have an oxidation state of +4? A. Mn(NO3)2 B. Mn2(SO4)3 C. Mn3(PO4)4 D. Mn3(PO4)5
In which compound does chromium have an oxidation state of +3? A. K2Cr2O7 B. Cr(NO3)2 C. Cr2(SO4)3 D. Cr3(PO4)2
The presence of calcium nitride in the product can be demonstrated by adding water. The nitride is hydrolysed to form calcium hydroxide and ammonia. (i) Calculate coefficients that balance the equation for the reaction: __ Ca3N2(s) + __ H2O(l) →…
What is the name of the compound with the formula Cr2(SO4)3? A. Chromium sulfate B. Chromium(II) sulfate C. Chromium(III) sulfate D. Chromium(VI) sulfate
In which species would nitrogen be oxidized if it were converted to N2O? A. NO2 B. NH4+ C. HNO3 D. N2O3
Which species could be reduced to form SO2? A. S8 B. H2S C. SO32− D. SO42−
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