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- The oxides of calcium and phosphorous react as shown below:-(Solved)
The oxides of calcium and phosphorous react as shown below:-
6CaO(s) + P4O10(s)--------->2Ca3(PO4)2(s)
(i) Give a reason why these substances react and yet both are oxides
(ii) Work out the oxidation state of phosphorous in P4O10
(iii) State one use of Ca3(PO4)2
Date posted: October 31, 2019. Answers (1)
- Explain how the pollution caused by large scale extraction of Zinc can be reduced by having a fertilizer plant close to it.(Solved)
Explain how the pollution caused by large scale extraction of Zinc can be reduced by having a fertilizer plant close to it.
Date posted: October 31, 2019. Answers (1)
- Give the chemical formula of Zinc blende(Solved)
Give the chemical formula of Zinc blende
Date posted: October 31, 2019. Answers (1)
- The following is an equation for the reaction between ammonia and water(Solved)
The following is an equation for the reaction between ammonia and water
Name the base in the backward reaction
Date posted: October 31, 2019. Answers (1)
- Calculate the volume at s.t.p of hydrogen evolved when 2A of electricity are passed
through dilute sulphuric acid for 2hours.
(Molar gas volume at s.t.p = 22.4dm3,...(Solved)
Calculate the volume at s.t.p of hydrogen evolved when 2A of electricity are passed
through dilute sulphuric acid for 2hours.
(Molar gas volume at s.t.p = 22.4dm3, one Faraday= 96500coulombs)
Date posted: October 31, 2019. Answers (1)
- State Faradays First Law of Electrolysis(Solved)
State Faradays First Law of Electrolysis
Date posted: October 31, 2019. Answers (1)
- Copper (II) sulphate solution was electrolysed using copper electrode. A Current of 0.5A was passed for 64.3 minutes and a mass of 0.64g of copper...(Solved)
Copper (II) sulphate solution was electrolysed using copper electrode. A Current of 0.5A was
passed for 64.3 minutes and a mass of 0.64g of copper was deposited. (Cu = 63.5)
a) Which electrode decreased in mass during electrolysis? Explain
b) Calculate the quantity of charge needed to deposits 1 mole of copper
Date posted: October 31, 2019. Answers (1)
- A student set up the experiment shown below. Study it and answer the questions that follow.(Solved)
A student set up the experiment shown below. Study it and answer the questions that follow.
a) State any two observations the student made during the experiment
b) Explain what happens to the pH of the resultant solution at the end of the experiment
Date posted: October 31, 2019. Answers (1)
- In the equation below identify the reagent that acts as an acid in the forward reaction.
Give a reason for your answer.(Solved)
In the equation below identify the reagent that acts as an acid in the forward reaction.
Give a reason for your answer.
Date posted: October 31, 2019. Answers (1)
- The following table shows the standard reduction potentials of some half cells. Study the table and refer to it to answer the questions that follow;(Solved)
The following table shows the standard reduction potentials of some half cells. Study the table and refer to it to answer the questions that follow;
a) Identify the strongest oxidizing agent
b) Which substance would be used to oxidize R- ion to the atom R
c) Study the cell represented below;
i) Identify the electrodes
ii) Write equations for the reaction taking place in each half- cell
iii) Determine the cell equation and the electromotive force (e.m.f) of the cell represented in
(c) above
iv) In which direction does the electrons flow in the external circuit of the cell whose e.m.f
is determined in (iii) above
d) A steady current of 2.5A was passed for 15 minutes through a cell containing divalent ions
M2+. During this process 0.74g of metal M was deposited (IF = 96500C)
i) Calculate the quantity of electricity passed in this cell
ii) Determine the relative atomic mass of M
Date posted: October 31, 2019. Answers (1)
- The reaction between ammonia and oxygen to form Nitrogen (II) oxide is highly exothermic(Solved)
The reaction between ammonia and oxygen to form Nitrogen (II) oxide is highly exothermic
4NH3(g) + 5O2(g)-------->4NO(g) + 6H2O(g)
The reaction is carried out in presence of platinium-rhodium catalyst at 1173k and a pressure of 911.952k pa.
Explain how each of the following would affect the yield of Nitrogen(II) oxide gas:
a) Reduction in pressure
b) Using a more efficient catalyst
Date posted: October 31, 2019. Answers (1)
- Sodium hydroxide may be manufactured by the electrolysis of brine as in the diagram below:-(Solved)
Sodium hydroxide may be manufactured by the electrolysis of brine as in the diagram below:-
(i) State the chemical name of brine
(ii) Write the equations for the reactions at the electrodes
-Anode
-Cathode
(iii) Explain how sodium hydroxide is obtained from the product of this process
Date posted: October 31, 2019. Answers (1)
- The diagram below shows a Zinc –copper cell.(Solved)
The diagram below shows a Zinc –copper cell.
(i) Given the standard electrode potential of Zinc is -0.76V and that of copper is +0.34V, suggest;
(i)The identity of W
(ii) The identity of X
(iii) The equation for the overall cell reaction
(iv) The reading on the voltmeter
Date posted: October 31, 2019. Answers (1)
- Cheptoo set-up some apparatus as shown in the diagram below:-(Solved)
Cheptoo set-up some apparatus as shown in the diagram below:-
At the start of the experiment, the bulb did not light:-
(a) State and explain the observation made when the tap was opened to allow the hydrogen chloride gas through the water for about 20 minutes
(b) Write the chemical equation for the reaction that took place at the cathode
Date posted: October 31, 2019. Answers (1)
- A student performed the following experiment with an intention to extract calcium metal(Solved)
A student performed the following experiment with an intention to extract calcium metal
(i) The student was surprised that no calcium was produced in the experiment. Explain why no calcium was produced
(ii) Write the equation for the reaction that occurred at the anode if the solution was concentrated
(iii) The electrolysis involved passing an electric current of 4A for one hour. Calculate the mass of
the product at the anode. (1Faraday = 96500C, Cl =35.5, H = 1.0, O =16, Ca = 40)
Date posted: October 31, 2019. Answers (1)
- A strip of copper metal was immersed into a nitrate solution of metal Q overnight. Use the information below to answer questions that follow(Solved)
A strip of copper metal was immersed into a nitrate solution of metal Q overnight. Use the information below to answer questions that follow
(a) State the observations made at the end of the experiment
(b) Give a reason for the observations made in (a) above
(c) Calculate the e.m.f of the cell above
Date posted: October 31, 2019. Answers (1)
- Below are the standard electrode potentials for electrodes B and D(Solved)
Below are the standard electrode potentials for electrodes B and D
(i) Identify the electrode which is ;
(a) The least reducing agent
(b) The strongest oxidizing agent
(ii) Calculate the e.m.f of the cell formed when the two electrodes are connected
(iii) Write a cell representative for the cell above
Date posted: October 31, 2019. Answers (1)
- The flow chart below shows an analysis of mixture R that contains two salts. Study it and answer the questions that follow:-(Solved)
The flow chart below shows an analysis of mixture R that contains two salts. Study it and answer the questions that follow:-
(i) Write two ionic equations for the reactions between the cation in filtrate X and aqueous
ammonia (Ammonium hydroxide)until in excess
(ii) What conclusion can be drawn from Step IV only? Explain
(iii) What observation would indicate the presence of a NO3- ion in step I?
(iv) Write the formula of the anion in residue V. Explain
(v) Suggest the identity of the cation present in solution Z
(vi) Name the two salts present in mixture R
Date posted: October 29, 2019. Answers (1)
- Study carefully the information given below and answer the questions that follow:-(Solved)
Study carefully the information given below and answer the questions that follow:-
(a) Identify the substances represented by the letters
(b) Give equations for the reactions in which:-
(i) Substance B is formed from the solution of A on electrolysis
(ii) Substance B is formed from solution A when reacted with E
(c) Give one use of gas C
(d) Name the ion responsible for the deep blue solution
Date posted: October 29, 2019. Answers (1)
- When nitrate solution of a certain metal X was electrolysed, 1.174g of metal X was deposited by a current of 4 amperes flowing for 16...(Solved)
When nitrate solution of a certain metal X was electrolysed, 1.174g of metal X was deposited by a current of 4 amperes flowing for 16 minutes. Determine the formula of the metal nitrate. (1F= 96,500, R.A.M of X= 59)
Date posted: October 29, 2019. Answers (1)