Enthalpy change that occurs when one mole of a substance is displaced from a solution of its ions.
sharon kalunda answered the question on May 16, 2019 at 13:50
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0.65 of zinc was reacted with 20cm3 of 2 M copper(II) sulphate solution in a plastic beaker.
The copper(II) sulphate solution was in excess. The initial...
(Solved)
0.65 of zinc was reacted with 20cm3 of 2 M copper(II) sulphate solution in a plastic beaker.
The copper(II) sulphate solution was in excess. The initial temperature and the highest temperature of the solution were recorded. 0.64 of copper metal was formed.
a) Other than change in temperature, state the observations made during the reaction
b) Calculate the
I Number of moles of Zinc that reacted (Zn=65)
II The number of moles of copper that was displaced from the solution (Cu=64)
III The mole ratio of Zn: Cu
Date posted:
May 16, 2019
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Answers (1)
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The grid below represents part of the periodic table. The letters do not represent the actual
symbols of the elements. Study it and answer the questions...
(Solved)
The grid below represents part of the periodic table. The letters do not represent the actual
symbols of the elements. Study it and answer the questions that follow.
a) Explain why element A is placed in two positions in the periodic table.
b) Name the type of bond and structure formed when element F reacts with element G.
c) Select one element which forms a highly soluble carbonate.
d) Which name is given to the group to which element D belong?.
e) Compare and explain the following:
i). Atomic radii of elements B and E.
ii). Electrical conductivity of elements E and H.
f)i). The oxide of element C was dissolved in water to form a solution of C. Compare the pH
value of the solution C with that of sodium chloride solution. Give a reason for your answer.
ii). Give ONE use of elements of which J is a member.
Date posted:
May 16, 2019
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Answers (1)
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State one use of radioactive isotope in (i). Medicine (ii). Industry.
(Solved)
State one use of radioactive isotope in
i). Medicine
ii). Industry.
Date posted:
May 16, 2019
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Answers (1)
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Radioactive carbon – 14 decays by emitting ß- Particle to form N-14. Write a nuclear
equation for the reaction.
(Solved)
Radioactive carbon – 14 decays by emitting β- Particle to form N-14. Write a nuclear
equation for the reaction.
Date posted:
May 16, 2019
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Answers (1)
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Distinguish between nuclear fission and nuclear fusion.
(Solved)
Distinguish between nuclear fission and nuclear fusion.
Date posted:
May 16, 2019
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Answers (1)
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The table below gives the percentage of a radioactive isotope of Bismuth that remains after decaying at different times.
(Solved)
The table below gives the percentage of a radioactive isotope of Bismuth that remains after
decaying at different times.
i). On the grid provided, plot a graph of the percentage of Bismuth remaining(Vertical axis) against
time.
ii) Using the graph determine the
i) Half- life of Bismuth isotope.
ii) Original mass of the Bismuth Isotope given that the mass that remained after 70
minutes was 0.16g.
Date posted:
May 16, 2019
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Answers (1)
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Study the flow chart below and use it to answer the questions between.
(Solved)
Study the flow chart below and use it to answer the questions between.
a) Identify the process described by the flow chart
b) Explain why the Ore is crushed
c) Which process occurs at mixing chamber?
d) Explain the use of ;
i) water
ii) Oil
e) Compressed air Write down an equation for the formation of slag.
f) Identify the cations present where the metal is being purified.
Date posted:
May 16, 2019
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Answers (1)
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The set – up below was used during the electrolysis of a solution of magnesium
sulphate using inert electrodes.
(Solved)
The set – up below was used during the electrolysis of a solution of magnesium
sulphate using inert electrodes.
i). Identify the ions present in the electrolyte
ii). Write half equations at the anode and at the cathode:
Cathode:
Anode
Date posted:
May 16, 2019
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Answers (1)
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Study the following table and then use it to answer the questions that follow
(Solved)
Study the following table and then use it to answer the questions that follow
These organic compounds belong to the same homologous series.
i). What is meant by the term homologous series?
ii). To which homologous series do the above hydrocarbons belong?
iii). Select one hydrocarbon that would be a liquid at room temperature 298K. Give a reason for your answer
iv). What is the relationship between the boiling point and the relative molecular masses of
the hydrocarbons in the table above? Explain your answer
v). Give one chemical test to distinguish between C2H6 and the third member to the homologous series of the general formula CnH2n.
Date posted:
May 16, 2019
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Answers (1)
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The diagram below represents an electrochemical cell. Write the overall ionic equation
(Solved)
The diagram below represents an electrochemical cell.
Write the overall ionic equation
Date posted:
May 16, 2019
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Answers (1)
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Dry chlorine gas was passed through two pieces of coloured cotton cloth as shown.
(Solved)
Dry chlorine gas was passed through two pieces of coloured cotton cloth as shown.
a) State what is observed in each experiment.
Experiment 1
Experiment 2
b) Explain your observation using an equation.
Date posted:
May 16, 2019
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Answers (1)
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The molar heat of formation of carbon (II) oxide is -105kJ/mol, molar heat of combustion of
carbon is -393kJ/mol.By using an energy cycle diagram, determine the...
(Solved)
The molar heat of formation of carbon (II) oxide is -105kJ/mol, molar heat of combustion of
carbon is -393kJ/mol.By using an energy cycle diagram, determine the molar heat of combustion of
Carbon(II)oxide.
Date posted:
May 16, 2019
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Answers (1)
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The system below is at equilibrium. Explain how an increase in the following affects the equilibrium position. (i) Temperature (ii) Pressure.
(Solved)
The system below is at equilibrium.
Explain how an increase in the following affects the equilibrium position.
(i) Temperature
(ii) Pressure.
Date posted:
May 16, 2019
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Answers (1)
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Bronze is an alloy of copper and another metal. Identify the other metal.
(Solved)
Bronze is an alloy of copper and another metal. Identify the other metal.
Date posted:
May 16, 2019
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Answers (1)
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During the extraction of copper and Zinc from their Ores, some of the processes include.
(i) Crushing
(ii) Mixing of the crushed Ore with Oil and water...
(Solved)
During the extraction of copper and Zinc from their Ores, some of the processes include.
(i) Crushing
(ii) Mixing of the crushed Ore with Oil and water and bubbling air through it.
(i) Name the process(ii) above.
(ii) What is the purpose of process (ii) above?
Date posted:
May 16, 2019
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Answers (1)
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The boiling and melting points of alkali metals decreases down the group while the melting and boiling points of halogens increase down the group.Explain
(Solved)
The boiling and melting points of alkali metals decreases down the group while the melting and boiling points of halogens increase down the group.Explain
Date posted:
May 16, 2019
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Answers (1)
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Helium is used instead of Hydrogen to fill balloons.Explain
(Solved)
Helium is used instead of Hydrogen to fill balloons.Explain
Date posted:
May 16, 2019
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Answers (1)
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A solution containing 0.1m sulphuric acid has a pH of 2 while 5M has a pH of more than two.
Explain.
(Solved)
A solution containing 0.1m sulphuric acid has a pH of 2 while 5M has a pH of more than two.
Explain.
Date posted:
May 16, 2019
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Answers (1)
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When a current of 2.5 amperes was passed through a cell containing N2+ ions of a metal for 25 minutes, the mass of the cathode increased by...
(Solved)
When a current of 2.5 amperes was passed through a cell containing N2+ ions of a metal for
25 minutes, the mass of the cathode increased by 0.36g. ( 1 faraday = 96500 coulombs).Determine the relative atomic mass of element N.
Date posted:
May 16, 2019
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Answers (1)
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State and explain the observation made in the set-up below.
(Solved)
State and explain the observation made in the set-up below.
Date posted:
May 16, 2019
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Answers (1)