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- A dry cell is constructed using the following substances. Zinc metal, graphite rod, ammonium chloride paste and manganese (IV) oxide mixed with carbon powder.
(a) State...(Solved)
A dry cell is constructed using the following substances. Zinc metal, graphite rod, ammonium chloride paste and manganese (IV) oxide mixed with carbon powder.
(a) State the roles of:
(i) Ammonium chloride paste.
(ii) Manganese (IV) oxide mixed with carbon powder.
(b) Given that:
Calculate the e m f of the cell given zinc forms the negative electrode.
Date posted: March 29, 2019. Answers (1)
- Dry hydrogen chloride gas was passed over heated iron wool as shown below.(Solved)
Dry hydrogen chloride gas was passed over heated iron wool as shown below.
(a) State the observation made in the combustion tube at the end of the experiment.
(b) Write the equation for the reaction taking place:-
(i) In the combustion tube.
(ii) Leading to production of the blue flame.
Date posted: March 29, 2019. Answers (1)
- A mass of 40g of a saturated solution of potassium chlorate at 250C yields 14g of potassium chlorate when evaporated to dryness. Calculate the solubility...(Solved)
A mass of 40g of a saturated solution of potassium chlorate at 250C yields 14g of potassium chlorate when evaporated to dryness. Calculate the solubility of potassium chloride at 250C.
Date posted: March 29, 2019. Answers (1)
- The diagram below is a set-up of apparatus used to react ammonia gas with iron (IV) chloride solution.(Solved)
The diagram below is a set-up of apparatus used to react ammonia gas with iron (IV) chloride solution.
(a) State the observation made in the beaker after a few minutes.
(b) Explain why the funnel is used to deliver the ammonia into the solution.
Date posted: March 29, 2019. Answers (1)
- Give one use of radioactive isotopes in industries.(Solved)
Give one use of radioactive isotopes in industries.
Date posted: March 29, 2019. Answers (1)
- 384g of radioactive element was reduced to 48g in 540 days. Determine the half-life of X.(Solved)
384g of radioactive element was reduced to 48g in 540 days. Determine the half-life of X.
Date posted: March 29, 2019. Answers (1)
- Study the table below and use it to answer the questions that follow.(Solved)
Study the table below and use it to answer the questions that follow.
(i) In which of the solution will phenolphthalein indicator be colourless.
(ii) Which of the solutions could be used to relieve heartburn? Explain.
Date posted: March 29, 2019. Answers (1)
- Study the reaction scheme below and answer the questions that follow.(Solved)
Study the reaction scheme below and answer the questions that follow.
(a) Write an ionic equation for the formation of the white precipitate.
(b) Write the formula of the complex ion present in the colourless solution Q.
Date posted: March 29, 2019. Answers (1)
- 100cm³ of sulphur (IV) oxide takes 20 seconds to diffuse through a porous plate. What volume of oxygen gas would diffuse through the same plate...(Solved)
100cm³ of sulphur (IV) oxide takes 20 seconds to diffuse through a porous plate. What volume of oxygen gas would diffuse through the same plate in 30 seconds under similar conditions. (S = 32, O = 16).
Date posted: March 29, 2019. Answers (1)
- Consider the following reaction at equilibrium.(Solved)
Consider the following reaction at equilibrium.
Complete the table below to show the effect of different factors on the position of equilibrium.
Date posted: March 29, 2019. Answers (1)
- In the down’s process (used for extraction of sodium) a certain salt is added to lower the melting point of sodium chloride from 8000C to...(Solved)
In the down’s process (used for extraction of sodium) a certain salt is added to lower the melting point of sodium chloride from 8000C to about 6000C.
(i) Identify the salt added.
(ii) Why is it necessary to lower the temperature?
(iii) Give one use of sodium.
Date posted: March 29, 2019. Answers (1)
- The set-up below shows how gas A was prepared and reacted with heated magnesium.(Solved)
The set-up below shows how gas A was prepared and reacted with heated magnesium.
(a) Give a reason why it is not advisable to heat magnesium before heating ammonium nitrite.
(b) (i) Identify gas A.
(ii) Write a chemical equation for the reaction between gas A and magnesium.
Date posted: March 29, 2019. Answers (1)
- The empirical formula of a compound is CH2 and its molecular mass is 42.
(a) What is the molecular formular of this compound?
(b) To which...(Solved)
The empirical formula of a compound is CH2 and its molecular mass is 42.
(a) What is the molecular formular of this compound?
(b) To which group of hydrocarbons does the compound above belong?
(c) Draw the structural formula of the fourth member of this series and give its IUPAC name.
Date posted: March 29, 2019. Answers (1)
- When 25cm³ of 0.5M HCl is added to 25cm³ of 0.5M NaOH the temperature of the solution rose from 230C to 260C. Given that the...(Solved)
When 25cm³ of 0.5M HCl is added to 25cm³ of 0.5M NaOH the temperature of the solution rose from 230C to 260C. Given that the density of the solution is 1gcmˉ³ and its specific heat capacity is 4.2Jgˉ¹Kˉ¹.
(a) Determine the amount f heat evolved that caused the temperature rise.
(b) Work out the molar enthalpy of neutralization for this reaction.y is 4.2Jgˉ¹Kˉ¹.
Date posted: March 29, 2019. Answers (1)
- Write down the property of concentrated sulphuric (VI) acid shown in the following reactions.(Solved)
Write down the property of concentrated sulphuric (VI) acid shown in the following reactions.
Date posted: March 29, 2019. Answers (1)
- The set-up was used to prepare carbon (IV) oxide and investigate its properties.(Solved)
The set-up was used to prepare carbon (IV) oxide and investigate its properties.
(a) Write an equation for the reaction in vessel B.
(b) What is the role of sodium hydroxide solution in the set-up?
(c) What would be observed if a burning splint is introduced at jet C?
Date posted: March 29, 2019. Answers (1)
- The formula for cane sugar is (C12H22O11). Use an equation to show what happens when sugar is added to conc.Sulphuric (VI) acid.(Solved)
The formula for cane sugar is (C12H22O11). Use an equation to show what happens when sugar is added to conc.Sulphuric (VI) acid.
Date posted: March 29, 2019. Answers (1)
- 20cm³ of a dibasic acid required 25cm³ of 0.1M NaOH for complete neutralization.
(a) How many moles of sodium hydroxide reacted with the dibasic acid?
(b)...(Solved)
20cm³ of a dibasic acid required 25cm³ of 0.1M NaOH for complete neutralization.
(a) How many moles of sodium hydroxide reacted with the dibasic acid?
(b) Calculate the concentration of the dibasic acid in moles per litre.
Date posted: March 29, 2019. Answers (1)
- When a compound X was heated, a brown gas and a black residue were produced. Give the formula of:
(i) The brown gas.
(ii) The black...(Solved)
When a compound X was heated, a brown gas and a black residue were produced. Give the formula of:
(i) The brown gas.
(ii) The black residue.
Date posted: March 29, 2019. Answers (1)
- 0.92g of ethanol were found to burn in excess air producing a temperature rise of 32.5oC in 200cm3 of water(C=12.0,H=1.0,O=16.0) Density of water is 1g/cm3,...(Solved)
0.92g of ethanol were found to burn in excess air producing a temperature rise of 32.5oC in 200cm3 of water(C=12.0,H=1.0,O=16.0) Density of water is 1g/cm3, specific heat capacity of water is 4.2KjKg-1K-1.
(a) Write the equation for the combustion of ethanol.
(b) Determine the molar heat of combustion of ethanol
Date posted: March 29, 2019. Answers (1)