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- The setup below was used to investigate the changes that take place when sodium hydroxide pellets dissolve in water.(Solved)
The setup below was used to investigate the changes that take place when sodium hydroxide pellets dissolve in water.
a) Why is a plastic beaker used instead of a metallic beaker?
b) State and explain the observations made in the above reaction
Date posted: October 28, 2019. Answers (1)
- Calculate the latent heat of vaporization of water
H2O(l)-------->H2O(g)(Solved)
Calculate the latent heat of vaporization of water
H2O(l)-------->H2O(g)
Given the following thermo chemical equations:-
Date posted: October 28, 2019. Answers (1)
- The rise in temperature when 50cm3 of sodium hydroxide is reacted with two acids is given
in the table below:-(Solved)
The rise in temperature when 50cm3 of sodium hydroxide is reacted with two acids is given
in the table below:-
Explain the difference in the temperature.
Date posted: October 28, 2019. Answers (1)
- Turning of fossil fuels has adverse environmental effects:-
a) Name two pollutants from the burning of petroleum products
b) Give one precaution taken to minimise the pollution...(Solved)
Turning of fossil fuels has adverse environmental effects:-
a) Name two pollutants from the burning of petroleum products
b) Give one precaution taken to minimise the pollution by fossil fuels
Date posted: October 28, 2019. Answers (1)
- Consider the following equilibrium reaction.(Solved)
Consider the following equilibrium reaction.
State and explain the effect of formation of hydrogen chloride if pressure was increased in the equation above
Date posted: October 28, 2019. Answers (1)
- Biogas is a mixture of mainly Carbon (IV) Oxide and methane.
(i) Give a reason why biogas can be used as a fuel
(ii) Other than fractional...(Solved)
Biogas is a mixture of mainly Carbon (IV) Oxide and methane.
(i) Give a reason why biogas can be used as a fuel
(ii) Other than fractional distillation, describe a method that can be used to determine the percentage of methane in biogas
Date posted: October 28, 2019. Answers (1)
- A typical electrolysis cell uses a current of 40,000 amperes. Calculate the mass (in Kg of aluminium produced in one hour). (Al = 27) (Faraday...(Solved)
A typical electrolysis cell uses a current of 40,000 amperes. Calculate the mass (in Kg of aluminium produced in one hour). (Al = 27) (Faraday = 96500 Coloumbs)
Date posted: October 28, 2019. Answers (1)
- Distinguish between molar latent heat of fusion and molar latent heat of vaporization(Solved)
Distinguish between molar latent heat of fusion and molar latent heat of vaporization
Date posted: October 28, 2019. Answers (1)
- Study the graph below and answer the questions which follow:(Solved)
Study the graph below and answer the questions which follow:
Explain the changes occurring between points BC and CD
Date posted: October 28, 2019. Answers (1)
- The grid below shows part of the periodic table. Use it to answer the questions that follow. The letters are not the actual symbols.(Solved)
The grid below shows part of the periodic table. Use it to answer the questions that follow. The letters are not the actual symbols.
i) Write the equation for the reaction that occurs between elements L and D
ii) The oxide of G reacts with both hydrochloric acid and sodium hydroxide. What is the nature of
the oxide of G?
iii) Explain why elements H has a higher boiling points than element D.
iv) State one use of element E
v) Compare and explain the atomic radius of B and C
vi) 11.5g of L was completely burnt in oxygen .Calculate the volume of gas that was used.
(L = 23, molar gas volume at room temperature is 24dm3)
Date posted: October 28, 2019. Answers (1)
- Sodium hydrogen carbonate was strongly heated.
Write an equation for the reaction(Solved)
Sodium hydrogen carbonate was strongly heated.
Write an equation for the reaction
Date posted: October 28, 2019. Answers (1)
- When 1.6g of ammonium nitrate were dissolved in 100cm3 of water, the temperature dropped by 6ºC. Calculate its enthalpy change. (Density of water = 1g/cm3,specific...(Solved)
When 1.6g of ammonium nitrate were dissolved in 100cm3 of water, the temperature dropped by 6ºC. Calculate its enthalpy change. (Density of water = 1g/cm3,specific heat capacity is 4.2kJ kg-1K-1)
Date posted: October 28, 2019. Answers (1)
- Bond energies for some bonds are tabulated below:-(Solved)
Bond energies for some bonds are tabulated below:-
Use the bond energies to estimate the enthalpy for the reaction
C2H4(g) + H2(g)----->C2H6(g)
Date posted: October 28, 2019. Answers (1)
- Study the table below and answer the questions that follow(Solved)
Study the table below and answer the questions that follow
a) Calculate the enthalpy change for the following reaction
C2H4(g) + Br2(g)------->C2H4Br2(g)
b) Name the type of reaction that took place in (a) above
Date posted: October 28, 2019. Answers (1)
- Nitrogen and hydrogen react reversibly according to the equation:-(Solved)
Nitrogen and hydrogen react reversibly according to the equation:-
The energy level diagram for the above reaction is shown below:-
(a) How would the yield of ammonia be affected by:
(i) A decrease in temperature
(ii) An increase in pressure
(b) How does a catalyst affect reversible reaction already in equilibrium?
(c) On the above diagram, sketch the energy level diagram that would be obtained when iron catalyst is added to the reaction
Date posted: October 28, 2019. Answers (1)
- Using the heats of combustion of the following substances, calculate the heat of formation of ethanol(Solved)
Using the heats of combustion of the following substances, calculate the heat of formation of ethanol
Date posted: October 28, 2019. Answers (1)
- The diagram below shows energy levels for the reaction(Solved)
The diagram below shows energy levels for the reaction
(a) Work out the activation energy for the reaction
(b) Calculate the heat of formation of HF
(c) Is the reaction endothermic or exothermic?
Date posted: October 28, 2019. Answers (1)
- Study the information in the following table and answer the questions that follow. The letters do not represent the actual chemical symbols of the elements.(Solved)
Study the information in the following table and answer the questions that follow. The letters do not represent the actual chemical symbols of the elements.
Which of the above elements are:
(i) Likely to be radioactive?
(ii) Able to form a compound with the highest ionic character?
Date posted: October 25, 2019. Answers (1)
- The heat of combustion of ethanol, C2H5OH is 1370KJ/mole.
(i) What is meant by heat of combustion?
(ii) Calculate the heating value of ethanol
(H = 1.0, C...(Solved)
The heat of combustion of ethanol, C2H5OH is 1370KJ/mole.
(i) What is meant by heat of combustion?
(ii) Calculate the heating value of ethanol
(H = 1.0, C = 12.0, O = 16.0)
Date posted: October 25, 2019. Answers (1)
- 6g of Potassium nitrate solid was added to 120cm3 of water in a plastic beaker.
The mixture was stirred gently and the following results were obtained.
Initial...(Solved)
6g of Potassium nitrate solid was added to 120cm3 of water in a plastic beaker.
The mixture was stirred gently and the following results were obtained.
Initial temperature = 21.50C
Final temperature = 17.0 0C
(a) Calculate the enthalpy change for the reaction
(Density =1g/cm3, C= 4.2jg-1K-1)
(b) Calculate the molar enthalpy change for the dissolution of potassium nitrate
(K=39, N= 14, O =16)
Date posted: October 25, 2019. Answers (1)