- Write an equation to show the effect of heat on the nitrate of: - (2marks)
- Potassium
- Silver
- Study the diagram below and use it to answer the questions that follow.
- State the observation made in the combustion tube. (1mark)
- Write an equation for the reaction that took place in the combustion tube. (1mark)
- Name gas P (1mark)
- A typical electrolysis cell used a current of 40,000 amperes. Calculate the mass (in Kg of aluminum produced in one hour. (Al = 27) (Faraday = 96500Coulombs).(3marks)
- Oxygen is obtained on large scale by the fractional distillation of air as shown on the flow chart below.
- Identify the substance that is removed at the filtration stage. (1mark)
- Explain why Carbon (IV) oxide and water are removed before liquefaction of air. (1mark)
- Identify the component that is collected at -186°C. (1mark)
- The flow chart below shows steps used in the extraction of zinc from one of its ores
- Name the process that is used in step 2 to concentrate the ore. (1mark)
- Write an equation for the reaction which takes place in step 3. (1mark)
- Name one use of lead. (1mark)
- In an attempt to prepare a gas, a student added concentrated hydrochloric acid to Potassium manganate (VII). The products were then passed through two wash bottles containing water and concentrated sulphuric acid
- Name the gas prepared………………………………………………………… (1mark)
- State the purpose of wash bottle:
- Containing water? (1mark)
- Containing concentrated sulphuric acid? (1mark)
- Starting with 50 cm3 of 2M sodium hydroxide, describe how a solid sample of pure sodium sulphate crystals can be prepared in the laboratory. (3 marks)
- The grid below shows a part of the periodic table. The letters do not represent the actual symbols. Use it to answer the questions that follow: -
- Why is it possible to place element E in both group I and VII? (1mark)
-
- What type of structure formed when element N and P react? (1mark)
- Why do most of the elements react? (1mark)
- The table below gives information about the major alkanes which are constituents of crude oil. Study it and answer the questions that follow:.
- Why is petrol highly flammable than diesel? (1mark)
- Explain why alkenes and alkynes are not contained in crude oil. (1mark)
- Give one use of bitumen. (1mark)
-
- Explain the importance of the high percentage of nitrogen in air. (1mark)
- Why is nitrogen used for storage of semen in artificial insemination? (1mark)
- A solution of bromine gas in water is an example of a chemical reaction in a state of balance. The reaction involved is represented by the equation below:
State and explain the observations made when hydrochloric acid is added to the mixture. - Concentrated hydrochloric acid that is 35% pure has a density of 1.18g/cm3. Calculate its concentration in moles per litre. (H=1.0 Cl=35.5) (3marks)
-
- State the reason for using Argon in electric light bulbs. (1mark)
- Study the information in the table below and answer the questions that follow. The letters do not represent the actual symbols of the elements.
Element
Electronic configuration
Boiling point
X
Y
Z
2.7
2.8.7
2.8.8.7
-188oC
-35oC
59oC
- What is the general name given to the group in which the elements? (1mark)
- Identify the element that is a solid at room temperature. Explain (1mark)
- Bond energies for some bonds are tabulated below: -
BOND
BOND ENERGY KJ/mol
H – H
436
C = C
610
C- H
410
C - C
345
Use the bond energies to estimate the enthalpy for the reaction. (3marks) - The diagram below shows three methods for collecting gases in the laboratory
- Name the methods A and B. (1mark)
- From the methods above, identify one that is suitable for collecting Sulphur (IV) oxide. Explain. (2 mark)
- The structure below represents a cleansing agent.
- State the type of cleansing agent represented above. (1 mark)
- State two disadvantage of using the other type cleansing agent. (2 marks)
- The diagram below represents a set-up that can be used for the electrolysis of dilute sulphuric acid
- Name the electrodes A and (1mark)
- Write an equation for the reaction taking place at electrode B. (1mark)
- What happens to the concentration dilute sulphuric acid as the reaction continues?(1mark)
-
- State the graham’s law of diffusion. (1mark)
- Calculate the relative formula mass of gas X given that the time taken by equal volume of nitrogen gas and gas X to diffuse through the same hole is 10 seconds and 20 seconds respectively. (2mks)
-
- Complete the following nuclear equation. (1mark)
- 100g of a radioactive substance was reduced to 12.5g within 15.6 years. Determine the half-life of the substance. (2marks)
- Complete the following nuclear equation. (1mark)
- Wooden splints F and G were placed in different zones of a Bunsen burner flame. The diagram below gives the observations that were made.
- Explain the difference between F and (1mark)
- Name the type of flame that was used in the above experiment. (1mark)
-
- Identify the acid and base in the forward reaction given by the equation below: (1mark)
- Using the above equation and your answer in (a) above, define the term acid.(1mark)
- Sulphur exists in two crystalline forms.
- Name one crystalline form of Sulphur. (1mk)
- State two uses of Sulphur. (2mks)
- Study the set up below and answer the questions that flows
State all the observations that would be made when the circuit is completed (3marks) - The diagram below shows the catalytic oxidation of ammonia gas. Use it to answer the questions thatfollow: -
- What metal could rod M be made of? (1mark)
- State and explain two observations made inside the conical flask. (2marks)
- State two distinctive features of a dynamic equilibrium. (2marks)
- 3.1 of an organic compound containing Carbon hydrogen and oxygen only produced 4.4g of Carbon (IV) oxide and 2.0g of water on complete combustion.
- Calculate its empirical formula. (2 marks)
- Calculate in molecular formula if its formula mass is 62. (1 mark)
-
- Nitric (V) acid prepared in the laboratory is yellow in colour. What causes the yellow colour? (1 mark)
- State any two observations that would be made when concentrated nitric(V) acid is added to copper turnings. (2 marks)
- The curves below were obtained when equal volumes of HCl acid of same concentration were reacted with 25.0g of Mabel chips. In one case, the acid was first warmed to a high temperature.
- Which curve represents the reaction involving warm hydrochloric acid? (1 mark)
- Suppose a graph of volume of CO2 produced against time was plotted, draw on the same axes a sketch to show the graphs of the reaction above and label them as warm acid and cold acid. (2 marks)
MARKING SCHEME
-
-
- A brown solid is formed p1
-
- Carbon (II) Oxide. p1
- Q = 40000 x 60 x 60 = 144000000cp1
Mass of Al = 144000000 x 27p1
3 x 96500
= 13.43kgp1 -
- Dust particlesp1
- They readily solidify hence may block the pipesp1
- Argonp1
-
-
- Chlorine gasp1
-
- Remove traces of hydrogen chloride gasp1
- Drying agentp1
- Add 50cm3 of 1.0M sulphuric (VI) acid / Add 25cm3 of 2.0M sulphuric (VI) acid to a beaker containing 50 cm3 of 2M sodium hydroxide and stir.p1 *
Heat the mixture to saturate while stirring.p1
Allow slow cooling to form crystals of sodium sulphate.p1 -
- Element E can loss or gain one electron to gain stability hence possible to place it in group I or group VII. p1
-
- Molecular structure. p1
- To gain stability/stable configuration. p1
-
- Petrol has low carbon hydrogen ratio than diesel hence more flammable. p1
- Alkenes and alkynes are more reactive than alkanes hence do not exist naturally. p1
- -Manufacture of Tar used in road tarmacking
- -Sealing of leakages on roofs. Any correct use p1
-
- It neutralizes air to prevent violent combustion reaction from occurring. p1
- Its inert and have very low b.pt of -196oC. p1
- -The yellow/orange colour intensifies. P1
- Adding hydrochloric acid increases concentration of H+ hence favoring backward reaction where more Br2 and H2O are formed. p1
- Consider 1000cm3 of the solution
Mass = 1000 x 1.18
= 1180g P1/2
% acid = 35/100 X 1180P1/2
= 413g of acid in 1000cm3 P
Molarity= 413/36.5
= 11.32MP
-
- To prevent filament from burning out. Provides an atmosphere in which burning cannot occur /provides an inert atmosphere. P
- HalogensP
- - ZP 1/2
- Because its boiling point is above the room temperature. P 1/2
-
-
- A- Downward delivery /upward displacement of air. P 1/2
B – Over water. P 1/2 - A – Denser than airP
- A- Downward delivery /upward displacement of air. P 1/2
-
- Soapless detergent P
- -Non- biodegradable resulting in pollution P
- waste a lot of soap during washing before lather is formed.
- causes stains/blemishes/marks on clothes/garment
- causes fur on electric appliances like kettle, boilers and pipes form
-
-
- The rate of diffusion of any gas is inversely proportional to the square root of its density at constants conditions of temperature and pressure. P1
- The rate of diffusion of any gas is inversely proportional to the square root of its density at constants conditions of temperature and pressure. P1
-
- F is place in the middle of the flame while G is placed at the upper region of the flameP1
- Non- luminous flameP1
-
- Acid …H2O (l) P1/2
Base …HSO4- (aq) P1/2 - An acid is a proton donor P1
- Acid …H2O (l) P1/2
-
- Rhombic or monoclinicü1 Sulphur.
- – For hardening rubber
- Manufacture of sulphuric acid ü1 Any one correct
- As a fungicide
- In making calcium hydrogen sulphite used in bleaching.
- -The bulb lights P
- Grey solid deposits at the cathode P
- Brown gas bubbles produced at the anode P -
- -The rate of forward reaction is equal to the rate of forward reaction. P
- At equilibrium the concentrations of reactants and products do not change. P -
-
- Contains dissolved NO2 gasP
- - A blue solution is formedP
- Effervescence of brown gas P
-
- Curve IIP
-
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