Date | May 2017 | Marks available | 1 | Reference code | 17M.2.sl.TZ2.2 |
Level | SL | Paper | 2 | Time zone | TZ2 |
Command term | State | Question number | 2 | Adapted from | N/A |
Question
An acidic sample of a waste solution containing Sn2+(aq) reacted completely with K2Cr2O7 solution to form Sn4+(aq).
State the oxidation half-equation.
Deduce the overall redox equation for the reaction between acidic Sn2+(aq) and Cr2O72–(aq), using section 24 of the data booklet.
Calculate the percentage uncertainty for the mass of K2Cr2O7(s) from the given data.
The sample of K2Cr2O7(s) in (i) was dissolved in distilled water to form 0.100 dm3 solution. Calculate its molar concentration.
10.0 cm3 of the waste sample required 13.24 cm3 of the K2Cr2O7 solution. Calculate the molar concentration of Sn2+(aq) in the waste sample.
Markscheme
Sn2+(aq) → Sn4+(aq) + 2e–
Accept equilibrium sign.
Accept Sn2+(aq) – 2e– → Sn4+(aq).
[1 mark]
Cr2O72–(aq) + 14H+(aq) + 3Sn2+(aq) → 2Cr3+(aq) + 7H2O(l) + 3Sn4+(aq)
Accept equilibrium sign.
[1 mark]
«13.239 g ± 0.002 g so percentage uncertainty» 0.02 «%»
Accept answers given to greater precision, such as 0.0151%.
[1 mark]
« [K2Cr2O7] = \(\frac{{13.239{\text{ g}}}}{{294.20{\text{ g}}\,{\text{mo}}{{\text{l}}^{ - 1}} \times 0.100{\text{ d}}{{\text{m}}^3}}}\) =» 0.450 «mol\(\,\)dm–3»
[1 mark]
n(Sn2+) = «0.450 mol\(\,\)dm–3 x 0.01324 dm3 x \(\frac{{3\,mol}}{{1\,mol}}\) =» 0.0179 «mol»
«[Sn2+] = \(\frac{{0.0179\,mol}}{{0.0100\,mol}}\) =» 1.79 «mol\(\,\)dm–3»
Award [2] for correct final answer.
[2 marks]
Examiners report
Syllabus sections
- 17N.2.sl.TZ0.2e.i: Identify the strongest reducing agent in the given list.
- 17N.1.sl.TZ0.22: Which of the following is a redox reaction? A. 3Mg (s) + 2AlCl3 (aq) → 2Al (s) + 3MgCl2...
- 17N.1.sl.TZ0.21: What are the oxidation states of chromium in (NH4)2Cr2O7 (s) and Cr2O3 (s)?
- 17N.2.hl.TZ0.7d: Identify the best reducing agent in the table above.
- 17N.1.hl.TZ0.30: Consider the following half-equations: I2 (s) + 2e– \( \rightleftharpoons \) 2I– (aq) ...
- 17M.3.sl.TZ2.5b.ii: Deduce the redox equation for the reaction of nickel(II) chloride solution with the metal...
- 17M.3.sl.TZ2.5b.i: Nickel is also used as a catalyst. It is processed from an ore until nickel(II) chloride...
- 17M.2.sl.TZ2.4a.iv: Deduce, giving a reason, which species is the reducing agent.
- 17M.2.sl.TZ2.4a.iii: Determine the oxidation state of nitrogen in the two reactants.
- 17M.2.sl.TZ2.2a.ii: Deduce the overall redox equation for the reaction between acidic Sn2+(aq) and Cr2O72–(aq),...
- 17M.1.hl.TZ2.36: Which compounds can be reduced? I. C2H4II. CH3COOHIII. CH3CHO A. I and II...
- 17M.1.hl.TZ2.28: Which element is reduced in the following decomposition? (NH4)2Cr2O7(s) → N2(g) + Cr2O3(s) +...
- 17M.1.sl.TZ2.22: Which of the following is not a redox reaction? A. CH4(g) + Cl2(g) → CH3Cl(g) +...
- 17M.1.sl.TZ2.21: Which element is reduced in the following decomposition? (NH4)2Cr2O7(s) → N2(g) + Cr2O3(s) +...
- 17M.1.sl.TZ2.19: Which of the following does not react with dilute HCl(aq)? A. Na2CO3 B. Cu C. ...
- 17M.2.hl.TZ1.4d: Suggest why experiments involving tetracarbonylnickel are very hazardous.
- 17M.2.hl.TZ1.4b: The nickel obtained from another ore, nickeliferous limonite, is contaminated with iron. Both...
- 17M.2.hl.TZ1.4a: Formulate an equation for the oxidation of nickel(II) sulfide to nickel(II) oxide.
- 17M.2.hl.TZ1.3c.i: Formulate an equation for the reaction between VO2+(aq) and V2+(aq) in acidic solution to...
- 17M.2.hl.TZ1.3b.ii: Identify, from the table, a non-vanadium species that could convert...
- 17M.2.hl.TZ1.3b.i: Identify, from the table, a non-vanadium species that can reduce VO2+(aq) to V3+(aq) but no...
- 17M.2.sl.TZ1.3b: Formulate an equation for the reaction between VO2+(aq) and V2+(aq) in acidic solution to...
- 17M.2.sl.TZ1.3a: Determine the oxidation state of vanadium in each of the following species.
- 17M.2.sl.TZ1.1a.i: Suggest how the change of iodine concentration could be followed.
- 17M.1.hl.TZ1.29: A reaction takes place when a rechargeable battery is used: Pb(s) + PbO2(s) + 4H+(aq) +...
- 17M.1.hl.TZ1.28: Which change represents oxidation? A. HClO4 to HClO3 B. N2 to NH3 C. N2O to...
- 17M.1.sl.TZ1.22: What is the oxidation half-equation in the redox reaction? 2S2O32–(aq) + I2(aq) → S4O62–(aq)...
- 17M.1.sl.TZ1.21: What is the order of decreasing reactivity of the metals (most reactive first)? Zn(s) +...
- 16N.3.sl.TZ0.1c: Despite widespread improvements in the provision of safe drinking water, the sale of bottled...
- 16N.2.hl.TZ0.4i: Magnesium chloride can be electrolysed. (i) Deduce the half-equations for the reactions at...
- 16N.2.sl.TZ0.4g: Magnesium chloride can be electrolysed. Deduce the half-equations for the reactions at each...
- 16N.2.sl.TZ0.1b: Determine the average oxidation state of carbon in ethene and in...
- 16N.1.sl.TZ0.21: Which is a correct statement for the reaction below? 2MnO4-(aq) + 6H+(aq) + 5NO2-(aq) →...
- 16N.1.sl.TZ0.17: Which experimental methods could be used to observe the progress of the following...
- 16M.2.hl.TZ0.1b: Phosphine is usually prepared by heating white phosphorus, one of the allotropes of...
- 16M.2.sl.TZ0.1b: Phosphine is usually prepared by heating white phosphorus, one of the allotropes of...
- 16M.1.hl.TZ0.30: Applying IUPAC...
- 16M.1.sl.TZ0.21: Applying IUPAC rules, what is the name of MnO2? A. Magnesium(II) oxide B. Manganese(II)...
- 15M.1.hl.TZ1.30: Which represents a redox reaction? A. ...
- 15M.1.hl.TZ2.30: Which is a redox reaction? A. ...
- 15M.2.hl.TZ1.6e: Bromine reacts with aqueous sodium...
- 15M.2.hl.TZ1.7a.ii: Determine the oxidation number of carbon in ethanol and ethanal. Ethanol: Ethanal:
- 15M.2.hl.TZ1.7a.iii: Deduce the half-equation for the oxidation of ethanol to ethanal.
- 15M.2.hl.TZ1.7a.iv: Deduce the overall redox equation for the reaction of ethanol to ethanal with acidified...
- 15M.2.hl.TZ2.8b.i: State the name of \({\text{C}}{{\text{r}}_{\text{2}}}{{\text{O}}_{\text{3}}}\).
- 15M.2.hl.TZ2.8c.i: Chromium forms the complex ion...
- 15M.2.hl.TZ2.8d.i: The dichromate ion,...
- 15M.2.hl.TZ2.8d.ii: Explain in terms of oxidation numbers whether iodine is oxidized or reduced in part (d) (i).
- 15M.1.sl.TZ1.23: Which represents a redox reaction? A. ...
- 15M.1.sl.TZ1.24: Which species can oxidize ethanol to ethanoic acid? A. \({{\text{I}}^ - }\) B. ...
- 15M.1.sl.TZ2.23: What are the oxidation states of each element in...
- 15M.1.sl.TZ2.24: What is the coefficient for I– when the following equation is balanced using the smallest...
- 15M.2.sl.TZ1.2d: Bromine reacts with aqueous sodium...
- 15M.2.sl.TZ1.7c.iii: Deduce the half-equation for the oxidation of ethanol to ethanal.
- 15M.2.sl.TZ1.7c.ii: Determine the oxidation number of carbon in ethanol and ethanal. Ethanol: Ethanal:
- 15M.2.sl.TZ1.7c.iv: Deduce the overall redox equation for the reaction of ethanol to ethanal with acidified...
- 14M.1.hl.TZ2.31: Which species are the oxidizing and reducing agents in the following...
- 14M.2.hl.TZ1.6a: Alcohols with the molecular formula...
- 14M.2.hl.TZ2.5c: (i) Deduce a balanced equation for the reaction between the chlorate(I) ion and sulfur...
- 14M.1.sl.TZ2.23: What are the correct oxidation numbers of chromium in...
- 14M.2.sl.TZ1.6a: Define oxidation in terms of electron transfer.
- 14M.1.sl.TZ1.23: At which side of the equation are electrons, \({{\text{H}}^ + }\) ions and...
- 14M.1.sl.TZ1.24: What are the correct names for \({\text{KMn}}{{\text{O}}_{\text{4}}}\) and...
- 14M.2.sl.TZ1.6b: (i) Deduce the oxidation number of chromium in...
- 14M.2.sl.TZ2.4d: (i) Deduce the coefficients required to balance the half-equations given below. ___...
- 14M.3.sl.TZ1.16b: (i) \(1.50 \times {10^{ - 4}}{\text{ mol}}\) of \({{\text{I}}^ - }{\text{(aq)}}\) was...
- 14N.2.hl.TZ0.10a: (i) Identify whether half-equation 1 represents oxidation or reduction, giving a reason...
- 14N.3.hl.TZ0.24a: In an acidic soil, nitrate ions may undergo reduction to form ammonium ions. Deduce a...
- 14N.1.sl.TZ0.23: Which species of vanadium has a different oxidation number from the rest? A. ...
- 14N.1.sl.TZ0.24: Which statement is correct for the following...
- 14N.2.sl.TZ0.8a: (i) Identify whether half-equation 1 represents oxidation or reduction, giving a reason...
- 13N.1.hl.TZ0.31: What is the name of \({\text{Mn}}{{\text{O}}_{\text{2}}}\)? A. Manganese(II) oxide B. ...
- 13N.1.hl.TZ0.32: Consider the following...
- 13N.2.hl.TZ0.6b.i: State the initial and final oxidation numbers of titanium and hence deduce whether it is...
- 13N.3.hl.TZ0.9b.iv: The reducing agent in the cytochrome oxidase reaction is a species that can be denoted as...
- 13N.1.sl.TZ0.24: Consider the following...
- 13N.2.sl.TZ0.5b.iii: Deduce which of the six species is the strongest oxidizing agent.
- 13N.1.sl.TZ0.23: What is the name of...
- 13N.2.sl.TZ0.5a.i: State the initial and final oxidation numbers of titanium and hence deduce whether it is...
- 13N.2.sl.TZ0.5b.i: Deduce which of the species would react with titanium metal.
- 13N.2.sl.TZ0.5b.ii: Deduce the balanced equation for this reaction.
- 13M.2.hl.TZ1.4e.i: The standard electrode potential for the half-equation involving ethanedioic acid...
- 13M.2.hl.TZ1.4d: Deduce the half-equation involving ethanedioic acid.
- 13M.2.hl.TZ1.7b.iv: Deduce the oxidation number of iron in...
- 13M.1.sl.TZ1.23: Which statement is correct about a reducing agent? A. It is reduced by gaining...
- 13M.1.sl.TZ1.24: What is the correct increasing order of reactivity of the metals X, Y and Z based on the...
- 13M.2.sl.TZ1.4b: Calculate the change in oxidation numbers of carbon and...
- 13M.2.sl.TZ1.4a: Define oxidation in terms of electron transfer.
- 13M.2.sl.TZ1.4c: Identify the oxidizing and reducing agents. Oxidizing agent: Reducing agent:
- 13M.3.sl.TZ1.D2b.i: State the chemical formula for potassium dichromate(VI).
- 13M.3.sl.TZ1.D2b.iii: State the oxidation number of chromium in the product.
- 13M.2.hl.TZ2.7b.ii: Deduce the oxidizing and reducing agents in this reaction. Oxidizing agent: Reducing...
- 13M.2.hl.TZ2.7a: Define oxidation in terms of oxidation number.
- 13M.2.hl.TZ2.7b.i: Deduce the balanced chemical equation for the redox reaction of copper, Cu(s), with nitrate...
- 13M.2.hl.TZ2.7c.iii: Deduce a balanced chemical equation, including state symbols, for the overall reaction which...
- 13M.1.sl.TZ2.23: Which statement describes a reducing agent? A. It is reduced and gains electrons. B. ...
- 13M.1.sl.TZ2.24: Which is the oxidizing agent in the following...
- 13M.2.sl.TZ2.1d.i: Define the term reduction in terms of electrons.
- 13M.2.sl.TZ2.1d.ii: Deduce the oxidation number of manganese in the \({\text{MnO}}_{\text{4}}^ - {\text{(aq)}}\)...
- 13M.2.sl.TZ2.1f.i: One titration was abandoned because a brown precipitate, manganese(IV) oxide, formed. State...
- 12N.1.sl.TZ0.23: What is the correct systematic name of MnO2? A. Manganese(II) oxide B. ...
- 12N.2.sl.TZ0.5a: (i) Define oxidation and reduction in terms of electron loss or...
- 10N.1.hl.TZ0.30: Consider the following...
- 10N.1.hl.TZ0.31: The following equations indicate reactions that occur...
- 10N.1.sl.TZ0.23: Consider the following...
- 10N.2.sl.TZ0.6b: (i) Define oxidation in terms of oxidation numbers. (ii) Deduce the oxidation states...
- 10N.2.sl.TZ0.6g: Nitric acid reacts with silver in a redox reaction. __ \({\text{Ag(s)}} + \) __...
- 09N.1.hl.TZ0.29: Which compound contains nitrogen with an oxidation number of +3? A. NH4Cl B. ...
- 09N.1.sl.TZ0.24: Which are redox reactions? I. ...
- 09N.2.sl.TZ0.1a: Deduce the balanced redox equation for this reaction in acidic solution.
- 09N.2.sl.TZ0.1c: Calculate the amount, in moles, of \({\text{MnO}}_4^ - \) used in the titration.
- 09N.2.sl.TZ0.4b: Both \({{\text{C}}_{\text{5}}}{{\text{H}}_{{\text{12}}}}\) and...
- 09N.2.sl.TZ0.1b: Identify the reducing agent in the reaction.
- 09N.3.sl.TZ0.C4a: State the change in oxidation number of the cadmium and deduce if it is acting as the...
- 09N.3.sl.TZ0.E2a: State what is meant by the term biochemical oxygen demand (BOD).
- 10M.2.sl.TZ1.1: (a) (i) Deduce the change in the oxidation numbers of copper and nitrogen in step...
- 10M.2.sl.TZ1.5b: (i) Deduce the order of reactivity of the four metals, cadmium, nickel, silver and zinc...
- 10M.1.sl.TZ2.24: In which species does sulfur have an oxidation number of 0? A. ...
- 10M.1.sl.TZ2.25: What is the reducing agent in the reaction...
- 10M.2.sl.TZ2.5c: (i) Determine the oxidation number of lead in Pb,...
- 09M.2.hl.TZ1.4a.i: State the half-equation for the oxidation of the iron(II) ions.
- 09M.2.hl.TZ1.4a.ii: State the half-equation for the reduction of the \({\text{MnO}}_4^ - \) ions in acidic solution.
- 09M.2.hl.TZ1.4a.iii: Deduce the overall redox equation for the reaction.
- 09M.2.hl.TZ1.7a.iii: Deduce which species acts as the oxidizing agent when the cell is operating.
- 09M.2.hl.TZ1.7b.i: \({{\text{[Co(}}{{\text{H}}_{\text{2}}}{\text{O}}{{\text{)}}_{\text{6}}}{\text{]}}^{2 + }}\)
- 09M.2.hl.TZ1.7b.iii: \({{\text{[CoC}}{{\text{l}}_{\text{4}}}{\text{]}}^{2 - }}\)
- 09M.2.hl.TZ1.7b.ii: \({\text{C}}{{\text{o}}_{\text{2}}}{{\text{(S}}{{\text{O}}_{\text{4}}}{\text{)}}_{\text{3}}}\)
- 09M.2.sl.TZ1.4a: Define oxidation in terms of electron transfer.
- 09M.2.sl.TZ1.4b.i: State the oxidation number of manganese in \({\text{KMn}}{{\text{O}}_{\text{4}}}\) and in...
- 09M.2.sl.TZ1.4b.ii: Deduce which species has been oxidized in this reaction and state the change in oxidation...
- 09M.3.sl.TZ1.E2c.i: State what happened to the \({{\text{O}}_{\text{2}}}\) in step 1 in terms of electrons.
- 09M.3.sl.TZ1.D3b.ii: State with a reason whether chromium in potassium dichromate(VI) is oxidised or reduced by...
- 09M.3.sl.TZ1.E2c.ii: State the change in oxidation number for manganese in step 2.
- 09M.3.sl.TZ1.E2a: Outline the meaning of the term biochemical oxygen demand (BOD).
- 09M.1.sl.TZ2.25: Which list represents the halogens in increasing order of oxidizing strength (weakest...
- 09M.1.sl.TZ2.12: Metal M has only one oxidation number and forms a compound with the formula...
- 09M.1.sl.TZ2.24: Which species is oxidized in the following...
- 09M.2.sl.TZ2.5b.i: Define oxidation in terms of oxidation numbers.
- 11M.1.hl.TZ1.36: What is the correct order of reaction types in the following sequence?
- 11M.2.hl.TZ1.9e.i: Deduce the oxidation number of the nitrogen in the reactants and product.
- 11M.2.hl.TZ1.9e.ii: Deduce the oxidation and reduction half-equations and identify the oxidizing agent for the...
- 11M.1.sl.TZ1.23: Which species could be reduced to form \({\text{N}}{{\text{O}}_{\text{2}}}\)? A. ...
- 11M.1.sl.TZ1.25: What happens to the manganese in the following...
- 11M.2.hl.TZ2.7b.ii: Deduce which species can reduce \({\text{S}}{{\text{n}}^{4 + }}{\text{(aq)}}\) to...
- 11M.2.hl.TZ2.7b.iii: Deduce which species can reduce \({\text{S}}{{\text{n}}^{2 + }}{\text{(aq)}}\) to Sn(s) under...
- 11M.2.hl.TZ2.7d.ii: Deduce the oxidation number of chromium in...
- 11M.2.hl.TZ2.7e.i: Explain why it is very difficult to obtain sodium from sodium chloride by any other method.
- 11M.2.hl.TZ2.7b.i: State the species which is the strongest oxidizing agent.
- 11M.2.hl.TZ2.7d.iii: State the balanced half-equation for the reduction of dichromate ions to chromium(III) ions.
- 11M.1.sl.TZ2.24: Consider the following reactions of three unknown metals X, Y and...
- 11M.2.sl.TZ2.2a.i: Deduce the oxidation number of antimony in stibnite.
- 11M.1.sl.TZ2.23: What happens to iodine when iodate ions, \({\text{IO}}_3^ - \), are converted to iodine...
- 11M.2.sl.TZ2.2a.ii: Deduce one other common oxidation number exhibited by antimony in some of its compounds.
- 11M.2.sl.TZ2.2b.i: Deduce the chemical equations for these two reactions.
- 11M.2.sl.TZ2.5b.iii: Deduce the overall equation for the reaction taking place in the voltaic cell and determine...
- 12M.1.sl.TZ2.23: What is the name of \({\text{C}}{{\text{u}}_{\text{2}}}{\text{S}}\)? A. Copper(I)...
- 12M.1.sl.TZ2.24: Consider the following...
- 12M.2.sl.TZ2.1d: (i) Deduce the oxidation numbers of oxygen present in each of the species below. (ii) ...
- 11N.2.hl.TZ0.7a: Distinguish between the terms oxidation and reduction in terms of oxidation numbers.
- 11N.2.hl.TZ0.7b: State the names of \({\text{C}}{{\text{r}}_{\text{2}}}{{\text{O}}_{\text{3}}}\) and...
- 11N.2.hl.TZ0.7c.i: Define the term oxidizing agent.
- 11N.2.hl.TZ0.7c.ii: \({\text{C}}{{\text{r}}_{\text{2}}}{\text{O}}_7^{2 - }{\text{(aq)}}\) and...
- 11N.1.sl.TZ0.8: Which of the following redox reactions take place? I. ...
- 11N.1.sl.TZ0.23: What is the correct decreasing order of reactivity of the metals X, Y and Z based on the...
- 11N.2.sl.TZ0.5a: Deduce the balanced chemical equation for the reaction between sodium and sulfur. State the...