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- 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)
- How does the pH value of 0.25M KOH(aq) compare with that of 0.25M ammonia solution?(Solved)
How does the pH value of 0.25M KOH(aq) compare with that of 0.25M ammonia solution?
Date posted: October 25, 2019. Answers (1)
- In an experiment, soap solution was added to three samples of water. The results below
show the volume of soap solution required to lather with 500cm3...(Solved)
In an experiment, soap solution was added to three samples of water. The results below
show the volume of soap solution required to lather with 500cm3 of each water sample before and after boiling
(i) Which water samples are likely to be soft?
(ii) Explain the change in volume of soap solution used in sample 2
Date posted: October 25, 2019. Answers (1)
- A solution of hydrogen chloride gas in methylbenzene has no effect on calcium carbonate.
A solution of hydrogen chloride in water reacts with calcium carbonate to...(Solved)
A solution of hydrogen chloride gas in methylbenzene has no effect on calcium carbonate.
A solution of hydrogen chloride in water reacts with calcium carbonate to produce a gas. Explain
Date posted: October 25, 2019. Answers (1)
- In the equilibrium given below:-(Solved)
In the equilibrium given below:-
What would be observed when Iron (III) Chloride is added to the equilibrium mixture. Explain
Date posted: October 25, 2019. Answers (1)
- Study the table below showing the solubility of substance K at various temperatures(Solved)
Study the table below showing the solubility of substance K at various temperatures
(a) What would happen if a sample of a saturated solution of the substance at 30oC is
heated to 70oC? Explain.
(b) What is the most likely state of substance K
Date posted: October 25, 2019. Answers (1)
- Study the following tests and observation and answer the questions that follow:-(Solved)
Study the following tests and observation and answer the questions that follow:-
Identify:-
(a) Substance responsible for:
I. Light blue precipitate
II. Deep blue solution
(b) Gas evolved in test III above
Date posted: October 25, 2019. Answers (1)
- A student attempted to prepare a gas using the set-up below. She could not collect any gas(Solved)
A student attempted to prepare a gas using the set-up below. She could not collect any gas
(a) Give two reasons why no gas was collected
(b) Which gas did the student intend to prepare?
Date posted: October 25, 2019. Answers (1)
- Two samples of hard water C and D were boiled. When tested with drops of soap, sample D formed lather easily while C did not:-
(a)...(Solved)
Two samples of hard water C and D were boiled. When tested with drops of soap, sample D formed lather easily while C did not:-
(a) Name the possible salt that caused hardness in sample D
(b) Explain how distillation can remove hardness in sample C
Date posted: October 25, 2019. Answers (1)
- The table shows solubility of potassium chlorate V(Solved)
The table shows solubility of potassium chlorate V
(a) Calculate the mass of solute and solvent in 90g of the saturated solution of the salt at 45oC
(b) A solution of the salt in 100g water contains 63g at 95oC. At what temperature will the solution start forming crystals when cooled
Date posted: October 25, 2019. Answers (1)
- Describe how you would prepare a dry sample of crystals of potassium sulphate starting with 100cm3 of 1M sulphuric (VI) acid.(Solved)
Describe how you would prepare a dry sample of crystals of potassium sulphate starting with 100cm3 of 1M sulphuric (VI) acid.
Date posted: October 25, 2019. Answers (1)
- In an experiment to determine solubility of sodium chloride, 10.0 cm3 of a saturated solution of sodium chloride weighing 10.70g were placed in a volumetric...(Solved)
In an experiment to determine solubility of sodium chloride, 10.0 cm3 of a saturated solution of sodium chloride weighing 10.70g were placed in a volumetric flask and diluted to a total of 500cm3. 25.0 cm3 of the diluted solution of sodium chloride reacted completely with 24.0 cm3 of 0.1M silver nitrate solution.
I. Calculate;
(i) Moles of silver nitrate in 24.0 cm3 of solution.
(ii) Moles of NaCl in 25.0 cm3 of solution.
(iii) Moles of NaCl in 500 cm3 of solution.
(iv) Mass of NaCl in 10.0 cm3 of saturated sodium chloride (Na = 23, Cl = 35.5)
(v) Mass of water in 10.0cm3 of saturated solution.
(vi) The solubility of NaCl in g/100g of waters.
Date posted: October 25, 2019. Answers (1)