KERBOODLE SUMMARY QUESTION: ES Flashcards
Write a stoichiometric equation with state symbols for the reaction of chlorine water mixed with aqueous sodium iodide
Cl2(aq) + 2NaI(aq) –> 2NaCl(aq) + I2(aq)
Write a stoichiometric equation with state symbols for the reaction of bromine water mixed with aqueous potassium iodide
<span>Br</span>2(aq) + 2KI(aq) –> 2KBr(aq) + I2(aq)
Write a stoichiometric equation with state symbols for the reaction of bromine water mixed with aqueous sodium chloride
no reaction
Write the two half-equations with state symbols for the following equation
Br2(aq) + 2I-(aq) –> 2Br-(aq) + I2(aq)
2Br2(aq) + 2e- –> 2Br-(aq)
2I-(aq) –> I2(aq) + 2e-
Write a balanced ionic equation for the following precipitation reactions when silver nitrate solution is added to potassium iodide solution
Ag+(aq) + I-(aq) –> AgI(s)
Write a balanced ionic equation for the following precipitation reactions when silver nitrate solution is added to sodium bromide solution
Ag+(aq) + Br-(aq) –> AgBr(s)
Write a balanced ionic equation for the following precipitation reactions when silver nitrate solution is added to copper(II) chloride solution
Ag+(aq) + Cl-(aq) –> AgCl(s)
Given that water in the Dead Sea has a bromide ion concentration of 5.2g dm-3 and a chloride ion concentration of 208g dm-3.
Calculate the concentration in mol dm-3 for bromide ions in Dead Sea water
0.065 mol dm-3
Given that water in the Dead Sea has a bromide ion concentration of 5.2g dm-3 and a chloride ion concentration of 208g dm-3.
Calculate the concentration in mol dm-3 for chloride ions in Dead Sea water
5.68 mol dm-3
Given that water in the Dead Sea has a bromide ion concentration of 5.2g dm-3 and a chloride ion concentration of 208g dm-3.
The simples ratio of bromide ions to chloride ions in the Dead Sea
Br-:Cl-
1:90
Predict what you would observe after silver chloride solution and excess dilute ammonia solution are added together and shaken
colourless solution
Predict what you would observe after chlorine water, potassium iodide solution, and cyclohexane, are added together and shaken
pale brown lower layer and violet upper layer
Predict what you would observe after sodium chloride solution, iodine solution, and cylclohexane are added together and shaken
pale brown lower layer and violet upper layer
Insert electrons, e-, on the appropriate side of the half-equation, in order to balance and complete them, so that the electrical charges on both sides are equal
K –> K+
Identify whether the process is oxidation or reduction
K –> K+ + e-
oxidation
Insert electrons, e-, on the appropriate side of the half-equation, in order to balance and complete them, so that the electrical charges on both sides are equal
H2 –> 2H+
Identify whether the process is oxidation or reduction
H2 –> 2H+ + 2e-
oxidation
Insert electrons, e-, on the appropriate side of the half-equation, in order to balance and complete them, so that the electrical charges on both sides are equal
O –> O2-
Identify whether the process is oxidation or reduction
O + 2e- –> O2-
reduction
Insert electrons, e-, on the appropriate side of the half-equation, in order to balance and complete them, so that the electrical charges on both sides are equal
Cr3+ –> Cr2+
Identify whether the process is oxidation or reduction
Cr3+ + e- –> Cr2+
reduction
Write down the oxidation state of Ag+
silver = +1
Write down the oxidation state of the elements in Al2O3
aluminium = +3, oxygen = -2
Write down the oxidation state of the elements in SO42-
sulfur = +6, oxygen =-2
Write down the oxidation state of the elements in P4
phosphorus = 0
Write down the oxidation state of the elements in SF6
sulfur = +6, fluorine = -1
Write down the oxidation state of the elements in PO43-
phosphorus = +5, oxygen = -2
Work out the oxidation state of chlorine in ClO2
+4
Work out the oxidation state of chlorine in HClO4
+7
Work out the oxidation state of chlorine in MgCl2
-1
Work out the oxidation state of chlorine in Cl2O7
+7
Work out the oxidation state of chlorine in HCl
-1
Work out the oxidation state of chlorine in Cl2O
+1
In the process for the manufacture of bromine from Dead Sea water, bromine is separated from other materials involved in the process.
Which properties of bromine make it possible to separate from water?
Bromine is not very soluble in water and so a lower and higher density bromine layer is formed. This can be run off from water that floats on top
In the process for the manufacture of bromine from Dead Sea water, bromine is separated from other materials involved in the process.
Which properties of bromine make it possible to separate from chlorine?
Bromine is separated from chlorine in the distillation column because they have different boiling points
Write an ionic equation with state symbols for the reaction of chlorine gas with aqueous bromide ions to produce aqueous chloride ions and bromine liquid
Cl2(aq) + 2Br-(aq) –> 2Cl-(aq) + Br2(l)
In the production of 1.0 tonne of bromine, what mass of chlorine is required in tonnes? Give your answer to 1 d.p
0.4 tonnes
In the production of 5.0g of bromine, what volume of chlorine is required at RTP? Give your answer to 2 s.f. and in dm3
The volume of one mole of gas at room temperature and pressure is 24.0 dm3
0.75 dm3
The reaction of halogens below is an example of a redox reaction. State which element is oxidised and which is reduced, give the oxidation state of each atom or ion before and after the reaction
H2 + Cl2 –> 2HCl
Identify by formula the oxidising agent and the reducing agent
hydrogen oxidised from 0 to +1
chlorine reduced from 0 to -1
Cl2 - oxidising agent
H2 - reducing agent
The reaction of halogens below is an example of a redox reaction. State which element is oxidised and which is reduced, give the oxidation state of each atom or ion before and after the reaction
2FeCl2 + Cl2 –> 2FeCl3
Identify by formula the oxidising agent and the reducing agent
iron oxidised from +2 to +3
elemental chlorine is reduced from 0 to -1
oxidation state of chlorine in FeCl2 remains -1
Cl2 - oxidising agent
Fe2+ - reducing agent
The reaction of halogens below is an example of a redox reaction. State which element is oxidised and which is reduced, give the oxidation state of each atom or ion before and after the reaction
2H2O + 2F2 –> 4HF + O2
Identify by formula the oxidising agent and the reducing agent
oxygen is oxidised from -2 to 0
fluorine is reduced from 0 to -1
hydrogen remains +1
F2 - oxidising agent
O2- - reducing agent
Use oxidation states to balance the following redox reaction
Br- + H+ + H2SO4 –> Br2 + SO2 + H2O
2Br- + 2H+ + H2SO4 –> Br2 + SO2 + 2H2O
Use oxidation states to balance the following redox reaction
I- + H+ + H2SO4 –> I2 + H2S + H2O
8I- + 8H+ + H2SO4 –> 4I2 + H2S + 4H2O
Use oxidation states to name SnO2
tin(IV) oxide
Use oxidation states to name FeCl2
iron(II) chloride
Use oxidation states to name NO3-
nitrate(V)
Use oxidation states to name PbCl4
lead(IV) chloride
Use oxidation states to name Mn(OH)2
manganese(II) hydroxide
Use oxidation states to name CrO42-
chromate(VI)
Use oxidation states to name VO3-
vandate(V)
Use oxidation states to name SO32-
sulfate(IV)
Write a formula for potassium chlorate(III).The negative ion has a charge of -1.
KClO2
Write a formula for sodium chlorate(V).The negative ion has a charge of -1.
NaClO3
Write a formula for iron(III) hydroxide.The negative ion has a charge of -1.
Fe(OH)3
Write a formula for copper(II) nitrate(V).The negative ion has a charge of -1.
Cu(NO3)2
Predict the products at the cathode and anode in the electrolysis of molten lead bromide
cathode: lead
anode: bromine (not bromide)
Predict the products at the cathode and anode in the electrolysis of molten sodium chloride
cathode: sodium
anode: chlorine (not chloride)
Predict the products at the cathode and anode in the electrolysis of molten zinc iodide
cathode: zinc
anode: iodine (not iodide)
Below is the equation for the electrolysis of sodium chloride:
2Cl-(aq) + 2H2O(l) –> Cl2(aq) + 2OH-(aq) + H2(g)
Calculate the amount (in moles) of sodium hydroxide, NaOH, in 1 tonne of solid sodium hydroxide
1 tonne = 1 000 000g
25 000 mol
Below is the equation for the electrolysis of sodium chloride:
2Cl-(aq) + 2H2O(l) –> Cl2(aq) + 2OH-(aq) + H2(g)
What amount (in moles) of chlorine, Cl2, is produced for each mole of NaOH?
0.5 mol
Below is the equation for the electrolysis of sodium chloride:
2Cl-(aq) + 2H2O(l) –> Cl2(aq) + 2OH-(aq) + H2(g)
Calculate the mass of chlorine produced at the same time as 1 tonne of sodium hydroxide
1 tonne is 1 000 000g
887 500g
Predict the products at the anode and cathode if sodium bromide solution was electrolysed with graphite electrodes
cathode: hydrogen
anode: bromine
Predict the products at the anode and cathode if aluminium nitrate solution was electrolysed with graphite electrodes
cathode: hydrogen
anode: oxygen
Predict the products at the anode and cathode if zinc bromide solution was electrolysed with graphite electrodes
cathode: zinc
anode: bromine
Write the half-equations for the cathode and anode in the electrolysis of zinc bromide solution with graphite electrodes
State whether they are reduction or oxidation
cathode: Zn2+ + 2e- –> Zn (reduction)
anode: 2Br- –> Br2 + 2e- (oxidation)
Write the half-equations for the cathode and anode in the electrolysis of sodium bromide solution with graphite electrodes
State whether they are reduction or oxidation
cathode: 2H+ + 2e- –> H2 (reduction)
anode: 2Br- –> Br2 + 2e- (oxidation)
Write the half-equations for the cathode and anode in the electrolysis of sodium hydroxide solution with graphite electrodes
State whether they are reduction or oxidation
cathode: 2H+ + 2e- –> H2 (reduction)
anode: 4OH- –> O2 + 2H2O + 2e- (oxidation)
Write the half-equations for the cathode and anode in the electrolysis of nitric acid with platinum electrodes
State whether they are reduction or oxidation
cathode: 2H+ + 2e- –> H2 (reduction)
anode: 2H2O –> O2 + 4H+ + 4e- (oxidation)
Write the half-equations for the cathode and anode in the electrolysis of copper nitrate solution with copper electrodes
State whether they are reduction or oxidation
cathode: Cu2+ + 2e- –> Cu (reduction)
anode: Cu –> Cu2+ + 2e- (oxidation)
Write an expression for Kc for the following reaction:
2NO(g) + O2(g) ⇌ 2NO2(g)
Kc = ([NO2]2)/([NO]2[O2])
Write an expression for Kc for the following reaction:
C2H6(g) ⇌ C2H4(g) + H2(g)
Kc = ([C2H4][H2])/([C2H6])
Write an expression for Kc for the following reaction:
<span>2HI</span>(g) ⇌ H2(g) + I2(g)
Kc = ([H2][I2])/([HI]2)
Write an expression for Kc for the following reaction:
CO2(aq) + H2O(l) ⇌ HCO3-(aq) + H+(aq)
Kc = ([HCO3-][H+])/([CO2][H2O])
Write an expression for Kc for the following reaction:
CH3COOH(l) + C3H7OH(l) ⇌ CH3COOC3H7(l) + H2O(l)
Kc = ([CH3COOC3H7][H2O])/([CH3COOH][C3H7OH])
Below is the equilibrium constant Kc for a reaction
Kc = ([SO3(g)]2)/([SO2(g)]2[O2(g)])
Write the balanced chemical equation for the reaction
2SO2(g) + O2(g) –> 2SO3(g)
A mixture of nitrogen and hydrogen was sealed in a steel vessel and held at 1000K until equilibrium was reached. The contents were then analysed. The results are given in the table below.
Write an expression for Kc for the reaction:
N2(g) + 3H2(g) ⇌ 2NH3(g)

Kc = ([NH3]2)/([N2][H2]3)
A mixture of nitrogen and hydrogen was sealed in a steel vessel and held at 1000K until equilibrium was reached. The contents were then analysed. The results are given in the table below.
Calculate a value for Kc for the reaction
N2(g) + 3H2(g) ⇌ 2NH3(g)

Kc = 2.09
When PCl5 is heated in a sealed container and maintained at a constant temperature, an equilibrium is established. At 523K, the below equilibrium concentrations were determined
Write an expression for Kc for the reaction:
PCl5(g) ⇌ PCl3(g) + Cl2(g)

Kc = ([PCl3][Cl2])/([PCl5])
When PCl5 is heated in a sealed container and maintained at a constant temperature, an equilibrium is established. At 523K, the below equilibrium concentrations were determined
Calculate a value for Kc for the reaction:
PCl5(g) ⇌ PCl3(g) + Cl2(g)

Kc = 0.196
For the reaction of aqueous chloromethane with alkali the equilibrium constant has a value of 1 x 1016 at room temperature
OH-(aq) + CH3Cl(aq) ⇌ CH3OH(aq) + Cl-(aq)
What does this tell you about the concentration of chloromethane at equilibrium?
Equilibrium constant is much greater than 1 so products favoued. Chloromethane concentration will be low.
Use Kc to explain how the position of equilibrium would change if acid was added to the reaction between carbon dioxide and water
CO2(aq) + H2O(l) ⇌ HCO3-(aq) + H+(aq)
if acid was added [H+(aq)] would increase. Some HCO3- and H+ react making more CO2 and H2O. The equilibrium position moves to the left
Calculate the amount of sodium thiosulfate in the 20.0 cm3 of solution with a concentration of 1.00 mol dm-3
Write your answer in standard form and to an appropriate number of significant figures
2.0 x 10-2 moles
Calculate the amount of sodium thiosulfate in the 24.6 cm3 of solution with a concentration of 0.0100 mol dm-3
Write your answer in standard form and to an appropriate number of significant figures
2.46 x 10-4 moles
In a titration, 10.00 cm3 of sodium chlorate(I) solution was pippeted into a conical flask before excess potassium iodide and sulfuric acid were added. A 0.500 mol dm-3 solution of sodium thiosulfate was then run into the conical flash. The end point was reached when 11.2 cm3 of sodium thiosulfate had been added. Calculate the concentration of sodium chlorate(I) solution to 3s.f.
0.280 mol dm-3
When chlorine gas reacts with water, it makes dilute hydrochloric acid and dilute chloric(I) acid, HClO. This is a reversible reaction. Write a balanced equation with state symbols
Cl2(g) + H2O(l) ⇌ HCl(aq) + HClO(aq)
Household bleach is diluted by making 10.0 cm3 of bleach up to 100 cm3 in a volumetric flask. To a 10.0 cm3 aliquot of this, excess acid and potassium iodide were added. A mean titre of 9.80 cm3 of 0.0100 mol dm-3 sodium thiosulfate solution was required to change the starch indicator to colourless. Calculate the concentration of the undiluted bleach to 3 s.f.
0.490 mol dm-3
Propanol can be dehydrated to produce propene and water:
CH3CH2CH2OH –> CH3CH=CH2 + H2O
Calculate the relative formula mass of propanol
60.0
Propanol can be dehydrated to produce propene and water:
CH3CH2CH2OH –> CH3CH=CH2 + H2O
Calculate the relative formula mass of propene
42.0
Propanol can be dehydrated to produce propene and water:
CH3CH2CH2OH –> CH3CH=CH2 + H2O
Calculate the atom economy of this reaction
70%
1-bromobutane, C4H9Br, will react (rather slowly) with water to produce butan-1-ol, C4H9OH, and hydrogen bromide
Write the equation for this reaction
C4H9Br + H2O –> C4H9OH + HBr
1-bromobutane, C4H9Br, will react (rather slowly) with water to produce butan-1-ol, C4H9OH, and hydrogen bromide
Calculate the atom economy of this reaction
47.8%
1-bromobutane, C4H9Br, will react (rather slowly) with water to produce butan-1-ol, C4H9OH, and hydrogen bromide
This reaction can be sped up using sodium hydroxide, NaOH, instead of water. In this case, the waste product of the reaction is not hydrogen bromide, HBr, but sodium bromide, NaBr
Write an equation for this reaction
C4H9Br + NaOH –> C4H9OH + NaBr
1-bromobutane, C4H9Br, will react (rather slowly) with water to produce butan-1-ol, C4H9OH, and hydrogen bromide
This reaction can be sped up using sodium hydroxide, NaOH, instead of water. In this case, the waste product of the reaction is not hydrogen bromide, HBr, but sodium bromide, NaBr
What effect would changing the reactant in this way have on the atom economy?
Decreases the atom economy (41.8%)
Write a balanced symbol equation with state symbols for the reaction of hydrogen iodide with ammonia
NH3(g) + HI(g) –> NH4I(s)
Write a balanced symbol equation with state symbols for the reaction of hydrogen iodide with concentrated sulfuric acid
H2SO4(aq) + 8HI(aq) –> H2S(g) + 4H2O(l) + 4I2(s)
1,2 - dichloroethane undergoes thermal cracking to give chloroethene
CH2ClCH2Cl –> CH2=CHCl + HCl
Calculate the percentage yield of this process if 10.0 tonnes of the 1,2-dichloroethane yield 2.0 tonnes of chloroethene
31.7%
1,2 - dichloroethane undergoes thermal cracking to give chloroethene
CH2ClCH2Cl –> CH2=CHCl + HCl
In this process 10.0 tonnes of the 1,2-dichloroethane yield 2.0 tonnes of chloroethene
Use the percentage yield and atom economy of this reaction to calculate how much in tonnes of the 1,2-dichloroethane is actually converted into chloroethene
0.400 tonnes
Explain why pure hydrogen chloride can be prepared by the addition of concentrated sulfuric acid to sodium chloride but the same method cannot be used to prepare hydrogen bromide from sodium bromide. Include any equations which help your explanation
Sodium chloride reacts with concentrated acid to make pure hydrogen chloride gas
NaCl(s) + H2SO4(aq) –> NaHSO4(aq) + HCl(g)
Sodium bromide first of all reacts with concentrated sulfuric acid to make hydrogen bromide
NaBr(s) + H2SO4(aq) –> NaHSO4(aq) + HBr(g)
However, the bromide ions produced are strong enough reducing agents to reduce the sulfuric acid which is present to sulphur dioxide
2H+(aq) + 2Br-(aq) + H2SO4(aq) –> SO2(g) + 2H2O(l) + Br2(l)
This means that adding concentrated sulfuric acid to sodium bromide would not be a good way to make hydrogen bromide gas because it won’t be pure
The gas made will be a mixture of:
Hydrogen bromide
Sulfur dioxide
Bromine vapour (since the reaction is exothermic)
Deacon process:
4HCl(g) + O2(g) ⇌ 2Cl2(g) + 2H2O(g)
Which element is oxidised and which element is reduced in the Deacon process?
Chlorine = oxidised Oxygen = reduced
Ethanol is produced industrially at about 70 atmospheres pressure and 300oC by the following reaction. The reaction needs a catalyst
C2H4(g) + H2O(g) ⇌ C2H5OH(g) ΔH = -46 kJ mol-1
Which of the following would move the position of equilibrium to the right?
A) Increasing the temperature
B) Increasing the concentration of steam
C) Decreasing the pressure
B) Increasing the concentration of steam
State the direction in which the position of equilibrium would move (if at all) if the pressure was increased by compressing the reaction mixture of:
2NO(g) + O2(g) ⇌ 2NO2(g)
to the right
State the direction in which the position of equilibrium would move (if at all) if the pressure was increased by compressing the reaction mixture of:
C2H6(g) ⇌ C2H4(g) + H2(g)
to the left
State the direction in which the position of equilibrium would move (if at all) if the pressure was increased by compressing the reaction mixture of:
2HI(g) ⇌ H2(g) + I2(g)
no effect
State the direction in which the position of equilibrium would move (if at all) if the pressure was increased by compressing the reaction mixture of:
2NO2(g) ⇌ N2O4(g)
to the right
State the direction in which the position of equilibrium would move (if at all) if the pressure was increased by compressing the reaction mixture of:
2CO(g) + O2(g) ⇌ 2CO2(g)
to the right
Write an equation for the reaction between hydrogen and oxygen to produce steam
2H2(g) + O2(g) ⇌ 2H2O(g)
Consider the reaction between hydrogen and oxygen to produce steam
Wrie an expression for Kc
Kc = ([H2O]2)/([H2]2[O2])
Consider the reaction between hydrogen and oxygen to produce steam
Describe and explain how the equilibrium position is affected by an increase in temperature
Forward reaction is exothermic. The equilibrium moves to the left
Consider the reaction between hydrogen and oxygen to produce steam
Describe and explain how the equilibrium position is affected by an increase in the total pressure
The equilibrium position moves to the right as well the products side has fewer molecules
For the Deacon process explain why adding excess oxygen would increase the yield of chlorine
HCl(g) + O2(g) ⇌ 2Cl2(g) + 2H2O(g) ΔH = -114 kJ mol-1
The equilibrium position moves to the right to use up the extra oxygen
For the Deacon process explain why decreasing the pressure would increase the yield of chlorine
HCl(g) + O2(g) ⇌ 2Cl2(g) + 2H2O(g) ΔH = -114 kJ mol-1
There are fewer molecules on the left hand side of the equation than on the right. The equilibrium position moves to the right
For the Deacon process explain why decreasing the temperature would increase the yield of chlorine
HCl(g) + O2(g) ⇌ 2Cl2(g) + 2H2O(g) ΔH = -114 kJ mol-1
The forward reaction is exothermic. The equilibrium position moves to the right
This equilibrium exists in bleach:
Cl2(aq) + 2NaOH(aq) ⇌ NaCl(aq) + NaOCl(aq) + H2O(l)
Explain why you should never use another cleaning product that is acidic alongside the bleach
Adding acid removes NaOH, so NaOH concentration decreases. The equilibrium position moves to the left producing more NaOH and Cl2. Chlorine is a toxic gas