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Explain the meanings of the following physical properties of laboratory gases.
(Solved)
Explain the meanings of the following physical properties of laboratory gases.
i) A chocking smell.
ii) An irritating smell.
iii) A neutral gas
Date posted:
May 16, 2019
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Answers (1)
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An element X has atomic number 3, relative atomic mass 6.94 and consists of two isotopes
of mass numbers 6 and 7.
(Solved)
An element X has atomic number 3, relative atomic mass 6.94 and consists of two isotopes
of mass numbers 6 and 7.
a) What is the mass number of the more abundant isotope of X?
b) Calculate the relative abundance of each of the isotopes.
Date posted:
May 16, 2019
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Answers (1)
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When burning magnesium ribbon is put into a gas jar of carbon (IV) oxide gas, it continues to
burn leaving behind white solid powder and black...
(Solved)
When burning magnesium ribbon is put into a gas jar of carbon (IV) oxide gas, it continues to
burn leaving behind white solid powder and black solid specks as residue write chemical
equation for the reaction that produces.
i) The white solid powder.
ii) Black solid specks.
Date posted:
May 16, 2019
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Answers (1)
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State two large scale uses of hard water.
(Solved)
State two large scale uses of hard water.
Date posted:
May 16, 2019
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Answers (1)
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Explain how dilute hydrochloric acid can be used to determine the type of hardness in a sample of tap water.
(Solved)
Explain how dilute hydrochloric acid can be used to determine the type of hardness in a sample of tap water.
Date posted:
May 16, 2019
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Answers (1)
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Describe hardness of water.
(Solved)
Describe hardness of water.
Date posted:
May 16, 2019
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Answers (1)
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A factory produces 63.6 tonnes of anhydrous Na2CO3 on a certain. Calculate the number of tonnes of sodium chloride used on this particular day. Assume...
(Solved)
A factory produces 63.6 tonnes of anhydrous Na2CO3 on a certain. Calculate the number of tonnes of sodium chloride used on this particular day. Assume the plant is working at 100% efficiency.(C = 12, H = 1, Cl = 35.5, Ca = 40, Na = 23)
Date posted:
May 16, 2019
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Answers (1)
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The flow chart below shows the manufacture of sodium carbonate. Study it carefully and
answer the questions that follow.
(Solved)
The flow chart below shows the manufacture of sodium carbonate. Study it carefully and
answer the questions that follow.
a)
i). What is ammoniacal brine?
ii). Ammoniacal brine reacts with carbon (IV) oxide to form a mixture of two salts
which produce Q. Write an equation to show formation of Q
Name two processes that are used to separate Q into NH4Cl and P
b) Give two uses of sodium carbonate produced in the process.
c)i). Name the substance that reacts with water that comes into the slaker
ii). What happens at the kiln?
d) Write an equation for the reaction that occurs when P is heated to form solid
Na2 CO3
e) Name two substances that are recycled in the process.
Date posted:
May 16, 2019
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Answers (1)
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Define the term molar heat of displacement
(Solved)
Define the term molar heat of displacement
Date posted:
May 16, 2019
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Answers (1)
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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)