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Chemistry 1010 Loader (Fall 2004)
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Chemistry 1010
Handout 4: Reactions, equations and Redox
1.
Write molecular and net-ionic (where applicable) equations for the
reactions that take place in the following experiments.
Sodium hydroxide solution reacts with zinc nitrate solution to
give a precipitate of zinc hydroxide.
(b) Copper(II) oxide dissolves in dilute hydrochloric acid.
(c) Potassium chromate reacts with lead(II) nitrate solution to
give a yellow precipitate.
(d) Magnesium ribbon reacts with dilute hydrochloric acid.
(e) Solid calcium carbonate reacts with dilute nitric acid to give
carbon dioxide gas.
(f) Potassium metal reacts with cold water to give hydrogen gas.
(g) Sodium hydrogen carbonate is heated strongly in a crucible
leaving a residue of sodium carbonate.
(h) Potassium chlorate is heated strongly with a catalyst to
produce oxygen gas.
(i) P4O10(s) react and dissolves in water to give a solution that
turns blue litmus paper red.
(j) Strontium oxide dissolves in water to give a solution that
turns red litmus paper blue.
(k) Aqueous barium nitrate reacts with aqueous lithium sulfate to
give a precipitate of solid barium sulfate and aqueous lithium
nitrate.
(l) lead(II) nitrate solution is mixed with sodium sulfate solution
(m) sodium hydroxide solution is added to a solution of ammonium
chloride (ammonia gas is evolved)
(n) calcium reacts with water
(o) copper(II) sulfide(s) reacts with dilute sulfuric acid
(p) aluminum sulfate solution is mixed with barium hydroxide
solution
(q) lithium oxide(s) is added to water
(r) sodium bromide solution is added to an acidified (H2SO4)
potassium chromate solution
5.
(a)
(c)
(e)
(f)
(a)
2.
3.
6.
7.
(a)
ClO2–(aq) → Cl2(g) in ACID solution
(b)
S2O32– → S4O62– in ACID solution
(c)
Cr(OH)3 → CrO42– in BASIC solution
(d)
N2H4 → N2 in BASIC solution
Balance the following redox equations.
(a)
8.
(b)
(a)
HCl
(e)
Na3AlCl6 (f)
HOCl
(c)
S2O32–
MnO42–
(g) NH3
(d)
As2O3
(h)
Mg2P2O7
(b)
Br2(aq) + SO2(g) → H2SO4(aq) + HBr(aq)
Cr2O72–(aq) + I–(aq) → Cr3+(aq) + I2(s) (acid solution)
Concentrated sulfuric acid has a density of 1.84 g.cm–3 (1.00 mL =
1.00 cm3) and contains 96% of H2SO4 by weight.
(b)
(c)
(a)
(b)
(c)
Write the formula for each of the following compounds:
potassium sulfide
antimony(III) sulfide
potassium chlorate
calcium sulfite dihydrate
(b)
(d)
(f)
(h)
barium chloride dihydrate
calcium hydride
sulfurous acid
chromium(III) oxide
Which of the following reactions is an oxidation-reduction
(REDOX) reaction. Write the NET-IONIC equation for each
reaction. Indicate where applicable, (i) the species being oxidized
and the species being reduced; and (ii) the oxidant (oxidizing
agent) and the reductant (reducing agent).
(a)
2 Cu2O + Cu2S → 6 Cu + SO2
MnO2(s) + PbO2(aq) → MnO4–(aq) + Pb2+(aq)
(c)
(a)
9.
sulfur in thiosulfate ion (b) nitrogen in NH4Cl
(d) uranium in UO2(NO3)2
zinc in Na2ZnO2
silicon in silicic acid (like carbonic acid)
phosphorus in the fertilizer called triple superphophate,
Ca(H2PO4)2
Write balanced half-reactions for each of the following partial half
reactions.
What is the oxidation number of the UNDERLINED atom?
(a)
(c)
(e)
(g)
4.
Calculate the oxidation number of the indicated element in each of
the following species.
Calculate the concentration of the concentrated sulfuric acid
in mol.L–1.
What volume of the concentrated sulfuric acid would be
required to make 2.50 litres of a 3.0 mol.L–1 solution of the
bench acid?
What is the mass of the volume of the acid calculated in (b)?
Calculate the concentration in mol.L–1 of a sodium hydroxide
solution 33.45 mL of which neutralizes 25.00 mL of 0.1500
mol.L–1 of nitric acid.
A 10.00 mL aliquot of dilute sulfuric acid required 16.12 mL
of 0.1021 mol.L–1 sodium hydroxide solution for
neutralization. What was the concentration of the sulfuric
acid solution?
A 0.64753 g sample of the hydroxide of an unknown metal
(M) required 34.30 mL of 0.4244 hydrochloric acid for
complete reaction. The hydroxide is insoluble in water and
may have the formula MOH, M(OH)2 or M(OH)3. Use the
information from the titration to deduce the most likely
formula and hence the molar mass of the metal.
10. A 50.00 mL sample of a solution containing iron(II) ions, Fe2+(aq),
was required 20.63 mL of a 0.0216 mol.L–1 solution of KMnO4 in
the reaction (unbalanced equation!):
8 H+(aq) + MnO4–(aq) + 5 Fe2+(aq) → Mn2+(aq) + 5 Fe3+(aq) + 4 H2O(l)
(a) Calculate the concentration of iron(II) ions in the solution.
(b) What volume of a 0.0150 mol.L–1 solution of KMnO4 solution
would be required to react completely with the iron(II) sulfate
solution formed when 0.23245 g of iron wire reacted with
sulfuric acid?
Fe(s) + H2SO4(aq) → FeSO4(aq) + H2(g)
(b)
AgNO3(aq) + NaCl(aq) → AgCl(aq) + NaNO3(aq)
(c)
2 Al(s) + 3 F2(g) → 2 AlF3(s)
(d)
2 K2CrO4(aq) + H2SO4(aq) → K2Cr2O7(aq) + K2SO4(aq)
(e)
Cl2(aq) + 2 KI(aq) → I2(aq) + 2 KCl(aq)
(a)
ClO3– + MnO4– → MnO2 + ClO4– (acidic)
(f)
Na2O(s) + H2O(l) → 2 NaOH(aq)
(b)
2 CuS(s) + 3 O2(g) → 2 CuO(s) + 2 SO2(g)
NO3– + S → NO + H2SO3 (acidic)
(g)
(c)
Cr2O72– H+ + I2 → IO3– + Cr3+ (acidic)
(d)
Zn + NO3– → ZnO22– + NH3 (basic)
(e)
S2– + ClO3– → Cl– + S (basic)
11. Balance the following equations in acid or base as indicated.
Identify the oxidant and the reductant.