9.1.REDOX-P2 [225 marks]
1.
[Maximum mark: 12]
Magnesium is a reactive metal often found in alloys.
(a)
(b)
22M.2.sl.TZ1.3
Magnesium can be produced by the electrolysis of molten
magnesium chloride.
Write the half-equation for the formation of magnesium.
[1]
Suggest an experiment that shows that magnesium is more
reactive than zinc, giving the observation that would confirm
this.
[2]
Organomagnesium compounds can react with carbonyl compounds. One
overall equation is:
(c(i))
State the name of Compound A, applying International Union
of Pure and Applied Chemistry (IUPAC) rules.
(c(ii)) Identify the strongest force between the molecules of
Compound B.
Compound B can also be prepared by reacting an alkene with water.
(d(i)) Draw the structural formula of the alkene required.
[1]
[1]
[1]
(d(ii)) Deduce the structural formula of the repeating unit of the
polymer formed from this alkene.
(e)
Deduce what would be observed when Compound B is
warmed with acidified aqueous potassium dichromate (VI).
[1]
[1]
Iodomethane is used to prepare CH3MgI. It can also be converted into methanol:
CH3I + HO– → CH3OH + I–
(f(i))
Identify the type of reaction.
(f(ii)) Outline the requirements for a collision between reactants to
yield products.
[1]
[2]
(f(iii)) The polarity of the carbon–halogen bond, C–X, facilitates attack
by HO–.
Outline, giving a reason, how the bond polarity changes going
down group 17.
[1]
2.
[Maximum mark: 23]
22M.2.sl.TZ1.1
When heated in air, magnesium ribbon reacts with oxygen to form magnesium
oxide.
(a(i))
Write a balanced equation for the reaction that occurs.
[1]
(a(ii)) State the block of the periodic table in which magnesium is
located.
[1]
(a(iii)) Identify a metal, in the same period as magnesium, that does
not form a basic oxide.
[1]
The reaction in (a)(i) was carried out in a crucible with a lid and the following
data was recorded:
Mass of crucible and lid = 47.372 ±0.001 g
Mass of crucible, lid and magnesium ribbon before heating = 53.726 ±0.001 g
Mass of crucible, lid and product after heating = 56.941 ±0.001 g
(b(i)) Calculate the amount of magnesium, in mol, that was used.
[1]
(b(ii)) Determine the percentage uncertainty of the mass of product
after heating.
[2]
(b(iii)) Assume the reaction in (a)(i) is the only one occurring and it
goes to completion, but some product has been lost from the
crucible. Deduce the percentage yield of magnesium oxide in
the crucible.
[2]
When magnesium is burnt in air, some of it reacts with nitrogen to form
magnesium nitride according to the equation:
3 Mg (s) + N2 (g) → Mg3N2 (s)
(c(i))
Evaluate whether this, rather than the loss of product, could
explain the yield found in (b)(iii).
(c(ii)) Suggest an explanation, other than product being lost from the
crucible or reacting with nitrogen, that could explain the yield
found in (b)(iii).
[1]
[1]
The presence of magnesium nitride can be demonstrated by adding water to the
product. It is hydrolysed to form magnesium hydroxide and ammonia.
(d(i)) Calculate coefficients that balance the equation for the
following reaction.
__ Mg3N2 (s) + __ H2O (l) → __ Mg(OH)2 (s) + __ NH3 (aq)
[1]
(d(ii)) Determine the oxidation state of nitrogen in Mg3N2 and in NH3.
[1]
(d(iii)) Deduce, giving reasons, whether the reaction of magnesium
nitride with water is an acid–base reaction, a redox reaction,
neither or both.
[2]
Most nitride ions are 14N3–.
(e(i))
State the number of subatomic particles in this ion.
[1]
(e(ii)) Some nitride ions are 15N3–. State the term that describes the
relationship between 14N3– and 15N3–.
[1]
(e(iii)) The nitride ion and the magnesium ion are isoelectronic (they
have the same electron configuration). Determine, giving a
reason, which has the greater ionic radius.
[1]
(f )
(g)
Suggest two reasons why atoms are no longer regarded as the
indivisible units of matter.
[2]
State the types of bonding in magnesium, oxygen and
magnesium oxide, and how the valence electrons produce
these types of bonding.
[4]
3.
[Maximum mark: 4]
22M.2.sl.TZ2.5
Molten zinc chloride undergoes electrolysis in an electrolytic cell at 450 °C.
(a)
Deduce the half-equations for the reaction at each electrode.
[2]
(b)
Deduce the overall cell reaction including state symbols. Use
section 7 of the data booklet.
[2]
4.
[Maximum mark: 9]
Lithium reacts with water to form an alkaline solution.
(a)
22M.2.sl.TZ2.1
Determine the coefficients that balance the equation for the
reaction of lithium with water.
[1]
A 0.200 g piece of lithium was placed in 500.0 cm3 of water.
(b(i)) Calculate the molar concentration of the resulting solution of
lithium hydroxide.
[2]
(b(ii)) Calculate the volume of hydrogen gas produced, in cm3, if the
temperature was 22.5 °C and the pressure was 103 kPa. Use
sections 1 and 2 of the data booklet.
[2]
(b(iii)) Suggest a reason why the volume of hydrogen gas collected
was smaller than predicted.
[1]
(c)
(d)
The reaction of lithium with water is a redox reaction. Identify
the oxidizing agent in the reaction giving a reason.
[1]
Describe two observations that indicate the reaction of lithium
with water is exothermic.
[2]
5.
[Maximum mark: 8]
21N.2.sl.TZ0.6
Biochemical oxygen demand (BOD) can be determined by the Winkler Method.
(a)
Outline what is measured by BOD.
(b)
A student dissolved 0.1240 ± 0.0001 g of Na2S2O3 to make
1000.0 ± 0.4 cm3 of solution to use in the Winkler Method.
Determine the percentage uncertainty in the molar
concentration.
[1]
[2]
A 25.00 cm3 sample of water was treated according to the Winkler Method.
Step I: 2Mn2+ (aq) + O2 (g) + 4OH− (aq) → 2MnO2 (s) + 2H2O (l)
Step II: MnO2 (s) + 2I− (aq) + 4H+ (aq) → Mn2+ (aq) + I2 (aq) + 2H2O (l)
Step III: 2S2O32− (aq) + I2 (aq) → 2I− (aq) + S4O62− (aq)
The iodine produced was titrated with 37.50 cm3 of 5.000 × 10−4 mol dm−3
Na2S2O3.
(c(i))
Calculate the amount, in moles of Na2S2O3 used in the titration.
[1]
(c(ii)) Deduce the mole ratio of O2 consumed in step I to S2O32− used
in step III.
[1]
(c(iii)) Calculate the concentration of dissolved oxygen, in mol dm−3,
in the sample.
[2]
(c(iv)) The three steps of the Winkler Method are redox reactions.
Deduce the reduction half-equation for step II.
[1]
6.
[Maximum mark: 12]
21M.2.sl.TZ1.4
Hydrogen peroxide can react with methane and oxygen to form methanol. This
reaction can occur below 50°C if a gold nanoparticle catalyst is used.
(a)
The diagram shows the Maxwell-Boltzmann curve for the
uncatalyzed reaction.
Draw a distribution curve at a lower temperature (T2) and show
on the diagram how the addition of a catalyst enables the
reaction to take place more rapidly than at T1.
[2]
(b)
The hydrogen peroxide could cause further oxidation of the
methanol. Suggest a possible oxidation product.
[1]
Methanol is usually manufactured from methane in a two-stage process.
CH4 (g) + H2O (g) ⇌ CO (g) + 3H2 (g)
CO (g) + 2H2 (g) ⇌ CH3OH (l)
(c(i))
Determine the overall equation for the production of methanol.
[1]
(c(ii)) 8.00 g of methane is completely converted to methanol.
Calculate, to three significant figures, the final volume of
hydrogen at STP, in dm3. Use sections 2 and 6 of the data
booklet.
[3]
Consider the first stage of the reaction.
CH4 (g) + H2O (g) ⇌ CO (g) + 3H2 (g)
(d(i)) Determine the enthalpy change, ΔH, in kJ. Use section 11 of the
data booklet.
Bond enthalpy of CO = 1077 kJ mol−1.
[3]
(d(ii)) State the expression for Kc for this stage of the reaction.
[1]
(d(iii)) State and explain the effect of increasing temperature on the
value of Kc.
[1]
7.
[Maximum mark: 7]
21M.2.sl.TZ1.3
Magnetite, Fe3O4, is another ore of iron that contains both Fe2+ and Fe3+.
(a)
Deduce the ratio of Fe2+:Fe3+ in Fe3O4.
[1]
Iron exists as several isotopes.
(b(i)) State the type of spectroscopy that could be used to determine
their relative abundances.
[1]
(b(ii)) State the number of protons, neutrons and electrons in each
species.
[2]
(c)
Iron has a relatively small specific heat capacity; the
temperature of a 50 g sample rises by 44.4°C when it absorbs 1
kJ of heat energy.
Determine the specific heat capacity of iron, in J g−1 K−1. Use
section 1 of the data booklet.
[1]
In acidic solution, hydrogen peroxide, H2O2, will oxidize Fe2+.
Fe2+ (aq) → Fe3+ (aq) + e−
(d(i)) Write the half-equation for the reduction of hydrogen peroxide
to water in acidic solution.
[1]
(d(ii)) Deduce a balanced equation for the oxidation of Fe2+ by
acidified hydrogen peroxide.
[1]
8.
[Maximum mark: 13]
Iron may be extracted from iron (II) sulfide, FeS.
21M.2.sl.TZ1.1
(a)
Outline why metals, like iron, can conduct electricity.
[1]
(b)
Justify why sulfur is classified as a non-metal by giving two of
its chemical properties.
[2]
Iron (II) sulfide, FeS, is ionically bonded.
(c(i))
Describe the bonding in this type of solid.
[2]
(c(ii)) State the full electron configuration of the sulfide ion.
[1]
(c(iii)) Outline, in terms of their electronic structures, why the ionic
radius of the sulfide ion is greater than that of the oxide ion.
[1]
(c(iv)) Suggest why chemists find it convenient to classify bonding
into ionic, covalent and metallic.
[1]
The first step in the extraction of iron from iron (II) sulfide is to roast it in air to
form iron (III) oxide and sulfur dioxide.
(d(i)) Write the equation for this reaction.
[1]
(d(ii)) Deduce the change in the oxidation state of sulfur.
[1]
(d(iii)) Suggest why this process might raise environmental concerns.
[1]
(e)
Explain why the addition of small amounts of carbon to iron
makes the metal harder.
[2]
9.
[Maximum mark: 11]
Nickel catalyses the conversion of propanone to propan-2-ol.
20N.2.sl.TZ0.4
(a)
Outline how a catalyst increases the rate of reaction.
[1]
(b)
Explain why an increase in temperature increases the rate of
reaction.
[2]
Discuss, referring to intermolecular forces present, the relative
volatility of propanone and propan-2-ol.
[3]
(c)
(d(i)) The diagram shows an unlabelled voltaic cell for the reaction
Pb
2+
(aq) + Ni (s) → Ni
2+
(aq) + Pb (s)
Label the diagram with the species in the equation.
[1]
(d(ii)) Suggest a metal that could replace nickel in a new half-cell and
reverse the electron flow. Use section 25 of the data booklet.
[1]
(d(iii)) Describe the bonding in metals.
[2]
(d(iv)) Nickel alloys are used in aircraft gas turbines. Suggest a physical
property altered by the addition of another metal to nickel.
[1]
10.
[Maximum mark: 28]
Chlorine undergoes many reactions.
(a(i))
20N.2.sl.TZ0.1
State the full electron configuration of the chlorine atom.
[1]
(a(ii)) State, giving a reason, whether the chlorine atom or the
chloride ion has a larger radius.
[1]
(a(iii)) Outline why the chlorine atom has a smaller atomic radius than
the sulfur atom.
[2]
(a(iv)) The mass spectrum of chlorine is shown.
NIST Mass Spectrometry Data Center Collection © 2014 copyright by the U.S. Secretary of
Commerce on behalf of the United States of America. All rights reserved.
Outline the reason for the two peaks at m/z =
35
and 37.
(a(v)) Explain the presence and relative abundance of the peak at
m/z = 74 .
2. 67 g
of manganese(IV) oxide was added to 200. 0
2. 00 mol dm
−3
HCl
cm
3
of
.
MnO 2 (s) + 4 HCl (aq) → Cl2 (g) + 2H2 O (l) + MnCl2 (aq)
[1]
[2]
(b(i)) Calculate the amount, in mol, of manganese(IV) oxide added.
[1]
(b(ii)) Determine the limiting reactant, showing your calculations.
[2]
(b(iii)) Determine the excess amount, in mol, of the other reactant.
[1]
(b(iv)) Calculate the volume of chlorine, in dm , produced if the
3
reaction is conducted at standard temperature and pressure
(STP). Use section 2 of the data booklet.
[1]
(b(v)) State the oxidation state of manganese in MnO and MnCl .
2
2
[2]
(b(vi)) Deduce, referring to oxidation states, whether MnO is an
oxidizing or reducing agent.
2
[1]
Chlorine gas reacts with water to produce hypochlorous acid and hydrochloric
acid.
Cl2 (g) + H2 O (l) ⇌ HClO (aq) + HCl (aq)
(c(i))
Hypochlorous acid is considered a weak acid. Outline what is
meant by the term weak acid.
[1]
(c(ii)) State the formula of the conjugate base of hypochlorous acid.
[1]
(c(iii)) Calculate the concentration of H
solution with a pH = 3. 61.
[1]
+
(aq)
in a HClO (aq)
(d(i)) State the type of reaction occurring when ethane reacts with
chlorine to produce chloroethane.
[1]
(d(ii)) Predict, giving a reason, whether ethane or chloroethane is
more reactive.
[1]
(d(iii)) Write the equation for the reaction of chloroethane with a
dilute aqueous solution of sodium hydroxide.
[1]
(d(iv)) Deduce the nucleophile for the reaction in d(iii).
[1]
(d(v)) Ethoxyethane (diethyl ether) can be used as a solvent for this
conversion. Draw the structural formula of ethoxyethane
[1]
(d(vi)) Deduce the number of signals and their chemical shifts in the
H NMR spectrum of ethoxyethane. Use section 27 of the data
booklet.
[2]
1
CCl2 F2
(e(i))
is a common chlorofluorocarbon, CFC.
Calculate the percentage by mass of chlorine in CCl
2
F2
.
(e(ii)) Comment on how international cooperation has contributed to
the lowering of CFC emissions responsible for ozone
depletion.
[2]
[1]
11.
[Maximum mark: 12]
This question is about peroxides.
(a)
19M.2.sl.TZ1.4
Suggest why many chemicals, including hydrogen peroxide,
are kept in brown bottles instead of clear colourless bottles.
Hydrogen peroxide decomposes to water and oxygen when a catalyst such as
potassium iodide, KI, is added.
KI (aq)
2H2O2 (aq) −−−−→ O2 (g) + 2H2O (l)
(b(i)) In a laboratory experiment solutions of potassium iodide and
hydrogen peroxide were mixed and the volume of oxygen
generated was recorded. The volume was adjusted to 0 at t = 0.
The data for the first trial is given below.
Plot a graph on the axes below and from it determine the
average rate of formation of oxygen gas in cm3 O2 (g) s−1.
[1]
[3]
Average rate of reaction:
(b(ii)) Additional experiments were carried out at an elevated
temperature. On the axes below, sketch Maxwell–Boltzmann
energy distribution curves at two temperatures T1 and T2, where
T2 > T1.
[2]
(b(iii)) Apart from a greater frequency of collisions, explain, by
annotating your graphs in (b)(ii), why an increased temperature
causes the rate of reaction to increase.
[2]
(b(iv)) MnO2 is another possible catalyst for the reaction. State the
IUPAC name for MnO2.
[1]
(c)
Comment on why peracetic acid, CH3COOOH, is always sold in
solution with ethanoic acid and hydrogen peroxide.
H2O2 (aq) + CH3COOH (aq) ⇌ CH3COOOH (aq) + H2O (l)
(d)
[1]
Sodium percarbonate, 2Na2CO3•3H2O2, is an adduct of sodium
carbonate and hydrogen peroxide and is used as a cleaning
agent.
Mr (2Na2CO3•3H2O2) = 314.04
Calculate the percentage by mass of hydrogen peroxide in
sodium percarbonate, giving your answer to two decimal
places.
[2]
12.
[Maximum mark: 13]
This question is about compounds of sodium.
(a(i))
19M.2.sl.TZ1.3
Describe the structure and bonding in solid sodium oxide.
[2]
(a(ii)) Write equations for the separate reactions of solid sodium oxide
and solid phosphorus(V) oxide with excess water and
differentiate between the solutions formed.
Sodium oxide, Na2O:
Phosphorus(V) oxide, P 4O10:
Differentiation:
(b)
[3]
Sodium peroxide, Na2O2, is formed by the reaction of sodium
oxide with oxygen.
2Na2O (s) + O2 (g) → 2Na2O2 (s)
Calculate the percentage yield of sodium peroxide if 5.00 g of
sodium oxide produces 5.50 g of sodium peroxide.
[2]
Sodium peroxide is used in diving apparatus to produce oxygen from carbon
dioxide.
2Na2O2 (s) + 2CO2 (g) → 2Na2CO3 (s) + O2 (g)
(c(i))
Determine the enthalpy change, ΔH, in kJ, for this reaction using
data from the table and section 12 of the data booklet.
[3]
(c(ii)) Outline why bond enthalpy values are not valid in calculations
such as that in (c)(i).
[1]
(d)
(e)
13.
The reaction of sodium peroxide with excess water produces
hydrogen peroxide and one other sodium compound. Suggest
the formula of this compound.
[1]
State the oxidation number of carbon in sodium carbonate,
Na2CO3.
[1]
[Maximum mark: 7]
Rhenium, Re, was the last element with a stable isotope to be isolated.
(a)
(b)
19M.2.sl.TZ2.4
Before its isolation, scientists predicted the existence of
rhenium and some of its properties.
Suggest the basis of these predictions.
[2]
Describe how the relative reactivity of rhenium, compared to
silver, zinc, and copper, can be established using pieces of
rhenium and solutions of these metal sulfates.
[2]
One chloride of rhenium has the empirical formula ReCl3.
(c(i))
State the name of this compound, applying IUPAC rules.
(c(ii)) Calculate the percentage, by mass, of rhenium in ReCl3.
[1]
[2]
14.
[Maximum mark: 18]
Ethyne, C2H2, reacts with oxygen in welding torches.
(a)
Write an equation for the complete combustion of ethyne.
19M.2.sl.TZ2.1
[1]
(b(i)) Deduce the Lewis (electron dot) structure of ethyne.
[1]
(b(ii)) Compare, giving a reason, the length of the bond between the
carbon atoms in ethyne with that in ethane, C2H6.
[1]
(b(iii)) Identify the type of interaction that must be overcome when
liquid ethyne vaporizes.
[1]
Ethyne reacts with steam.
C2H2 (g) + H2O (g) → C2H4O (g)
Two possible products are:
(c(i))
Product A contains a carbon–carbon double bond. State the
type of reactions that compounds containing this bond are
likely to undergo.
[1]
(c(ii)) State the name of product B, applying IUPAC rules.
[1]
(c(iii)) Determine the enthalpy change for the reaction, in kJ, to
produce A using section 11 of the data booklet.
[3]
(c(iv)) The enthalpy change for the reaction to produce B is −213 kJ.
Predict, giving a reason, which product is the most stable.
[1]
(c(v)) The IR spectrum and low resolution 1H NMR spectrum of the
actual product formed are shown.
Deduce whether the product is A or B, using evidence from
these spectra together with sections 26 and 27 of the data
booklet.
Identity of product:
One piece of evidence from IR:
One piece of evidence from 1H NMR:
Product B, CH3CHO, can also be synthesized from ethanol.
[2]
(d(i)) Suggest the reagents and conditions required to ensure a good
yield of product B.
Reagents:
Conditions:
15.
[2]
(d(ii)) Deduce the average oxidation state of carbon in product B.
[1]
(d(iii)) Explain why product B is water soluble.
[3]
[Maximum mark: 7]
Propan-2-ol is a useful organic solvent.
18N.2.sl.TZ0.2
(a)
Draw the structural formula of propan-2-ol.
[1]
(b)
Calculate the number of hydrogen atoms in 1.00 g of propan-2ol.
[2]
Classify propan-2-ol as a primary, secondary or tertiary alcohol,
giving a reason.
[1]
State a suitable oxidizing agent for the oxidation of propan-2-ol
in an acidified aqueous solution.
[1]
Deduce the average oxidation state of carbon in propan-2-ol.
[1]
(c)
(d.i)
(d.ii)
(d.iii) Deduce the product of the oxidation of propan-2-ol with the
oxidizing agent in (d)(i).
[1]
16.
[Maximum mark: 9]
Bromine can form the bromate(V) ion, BrO3−.
(a.i)
State the electron configuration of a bromine atom.
(a.ii)
Sketch the orbital diagram of the valence shell of a bromine
atom (ground state) on the energy axis provided. Use boxes to
represent orbitals and arrows to represent electrons.
18N.2.sl.TZ0.3
[1]
[1]
(b)
(c)
Draw the Lewis (electron dot) structure for BrO3− that obeys the
octet rule.
[1]
Predict, using the VSEPR theory, the geometry of the BrO3− ion
and the O−Br−O bond angles.
[3]
(d.i)
Bromate(V) ions act as oxidizing agents in acidic conditions to
form bromide ions.
Deduce the half-equation for this reduction reaction.
(d.ii)
Bromate(V) ions oxidize iron(II) ions, Fe2+, to iron(III) ions, Fe3+.
[2]
Deduce the equation for this redox reaction.
[1]
17.
[Maximum mark: 11]
Trends in physical and chemical properties are useful to chemists.
(a)
(b)
(c)
(d)
17N.2.sl.TZ0.2
Explain the general increasing trend in the first ionization
energies of the period 3 elements, Na to Ar.
[2]
Explain why the melting points of the group 1 metals (Li → Cs)
decrease down the group.
[2]
State an equation for the reaction of phosphorus (V) oxide,
P 4O10 (s), with water.
[1]
Describe the emission spectrum of hydrogen.
[2]
The Activity series lists the metal in order of reactivity.
(e.i)
Identify the strongest reducing agent in the given list.
(e.ii)
A voltaic cell is made up of a Mn2+/Mn half-cell and a Ni2+/Ni
half-cell.
Deduce the equation for the cell reaction.
(e.iii) The voltaic cell stated in part (ii) is partially shown below.
Draw and label the connections needed to show the direction
of electron movement and ion flow between the two half-cells.
[1]
[1]
[2]
18.
[Maximum mark: 3]
17M.2.sl.TZ1.3
Vanadium, another transition metal, has a number of different oxidation states.
(a)
Determine the oxidation state of vanadium in each of the
following species.
[2]
(b)
Formulate an equation for the reaction between VO2+(aq) and
V2+(aq) in acidic solution to form V3+(aq).
[1]
19.
[Maximum mark: 5]
17M.2.sl.TZ1.1
The rate of the acid-catalysed iodination of propanone can be followed by
measuring how the concentration of iodine changes with time.
I2(aq) + CH3COCH3(aq) → CH3COCH2I(aq) + H+(aq) + I−(aq)
(a.i)
(a.ii)
Suggest how the change of iodine concentration could be
followed.
[1]
A student produced these results with [H+] = 0.15 moldm−3.
Propanone and acid were in excess and iodine was the limiting
reagent.
Determine the relative rate of reaction when [H+] = 0.15
moldm−3.
[2]
(b)
The student then carried out the experiment at other acid
concentrations with all other conditions remaining unchanged.
[2]
State and explain the relationship between the rate of reaction
and the concentration of acid.
20.
[Maximum mark: 6]
17M.2.sl.TZ2.2
2+
An acidic sample of a waste solution containing Sn (aq) reacted completely
with K2Cr2O7 solution to form Sn4+(aq).
(a.i)
State the oxidation half-equation.
[1]
(a.ii)
Deduce the overall redox equation for the reaction between
acidic Sn2+(aq) and Cr2O72–(aq), using section 24 of the data
booklet.
[1]
(b.i)
Calculate the percentage uncertainty for the mass of K2Cr2O7(s)
from the given data.
[1]
(b.ii)
The sample of K2Cr2O7(s) in (i) was dissolved in distilled water to
form 0.100 dm3 solution. Calculate its molar concentration.
(b.iii) 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.
[1]
[2]
21.
[Maximum mark: 7]
Bonds can be formed in many ways.
17M.2.sl.TZ2.4
The landing module for the Apollo mission used rocket fuel made from a mixture
of hydrazine, N2H4, and dinitrogen tetraoxide, N2O4.
N2H4(l) + N2O4(l) → 3N2(g) + 4H2O(g)
(a.i)
(a.ii)
State and explain the difference in bond strength between the
nitrogen atoms in a hydrazine and nitrogen molecule.
[2]
State why hydrazine has a higher boiling point than dinitrogen
tetraoxide.
[1]
(a.iii) Determine the oxidation state of nitrogen in the two reactants.
[1]
(a.iv) Deduce, giving a reason, which species is the reducing agent.
[1]
(b)
[2]
Deduce the Lewis (electron dot) structures of ozone.
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