Questions
- From the following list of compunds;zinc oxide,solid carbon (IV) oxide,sodium carbonate,nitric (V) acid,iron (III) chloride;
- Identify two that sublime.(2 mks)
- Identify a pair that react to form salt and water only.(2 mks)
- Write a word equation for the reaction between sodium carbonate and nitric (V) acid.(1 mk)
- In an experiment to investigate the percentage of oxygen in air,200cm³ of air was passed over heated copper turning repeatedly until a constant volume of air remained.160 cm³ of air remained at the end of the experiment.
- Name one gas remaining in the 160 cm³ of air.(1 mk)
- Determine the percentage of air used up during the experiment.(2 mks)
- What observation would be made during the experiment.(1 mk)
- Write a word equation for the reaction between copper and oxygen.(1 mk)
- Name the best method to use to separate the following mixtures.(4 mks)
- Common salt and water.
- Coloured dyes in ethanol.
- Ammonium chloride and sodium chloride.
- Ethanol and water.
- Study the set up below and answer the questions that follow.
- Identify gas X.(1 mk)
- Name the method used to collect gas X and give the property of the gas that enables it to be collected using the method.(2 mks)
- Write a word equation for the reaction liberating gas X.(1 mk)
- Why is not advisable to use the following in this method of preparing hydrogen;
- Calcium and dilute sulphuric acid(1 mk)
- Zinc and Nitric (V) acid.(1mk)
- What is the purpose of anhydrous calcium chloride in the U-tube?(1mk)
- Name another compound that could serve the same purpose as anhydrous calcium chloride.(1 mk)
- When magnesium is burnt in air,it reacts with oxygen and nitrogen gas giving a white ash.Write two equations for the two reactions that take place.(2 mks)
- The diagram below was used to investigate the action of water on calcium metal.
- Identify gas R.(1 mk)
- The remaining solution in the beaker changes red litmus paper to blue.What does this suggest about the resulting solution.(1 mk)
- Write a word equation for the reaction.(1 mk)
- What would be observed if Carbon(IV)oxide is bubbled through the solution.(1 mk)
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- Name the particles that are found in an atom.(3 mks)
- Atoms are said to be electrically neutral.Explain.(2 mks)
- Element Q has 18 neutrons and a mass number of 34.
- How many protons are present in element Q?(1 mk)
- Write the electron arrangement of element Q.(1 mk)
- To which period and group does Q belong?Explain your answer.(2 mks)
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- In an experiment to investigate what happens when steam is passed over heated magnesium,wet sand or cotton wool soaked in water is heated first before heating magnesium.Why is it necessary?(1 mk)
- Write a word equation for the reaction between magnesium and steam.(1 mk)
- Write a word equation for the reaction between iron and steam.(1 mk)
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- What is the chemical name of rust?(1 mk)
- A form one student in attempt to stop rusting put copper and magnesium in contact with iron as shown.
- The set ups were left outside for two weeks.Where did rusting occur?Explain.(2 mks)
- Name the method used by the student to prevent rusting.(1mk)
- How does painting prevent rusting?(1 mk)
- State the use of the following apparatus as used in the laboratory.
- Pipe-clay triangle(1 mk)
- Desiccator(1 mk)
- Wire gauze(1 mk)
- The diagram below represents a set up for the laboratory preparation of oxygen gas.
- Name solid R.(1 mk)
- Write a word equation for the reaction in the flask.(1 mk)
- How can one test for oxygen gas?(2 mks)
- Give two commercial uses of oxygen gas.(2 mks)
- A student was supplied with a colourless liquid suspected to be water.
- Describe one test that could be carried out to show that the liquid was water.(2 mks)
- How could it have been shown that the liquid was pure water?(1 mk)
- Describe one test that could be carried out to show that the liquid was water.(2 mks)
- When a student was stung by a stinging nettle plant,a teacher applied an aqueous solution of ammonia to the affected area of the skin and the student was relieved of pian.Explain.(2 mks)
- A mixture of magnesium powder and lead (II)oxide will react vigorously when heated but no reaction occurs when a mixture of magnesium oxide and lead powder are heated.
- Explain the observations above.(2 mks)
- Write a word equation for the reaction between magnesium and lead(II) oxide.(1 mk)
- From (b) above,identify the;
- oxidised substance.(1 mk)
- oxidizing agent.(1 mk)
- what name is given to such a reaction?(1 mk)
- Classify the following as either physical or chemical changes.(5 mks)
- Freezing of beer
- Rusting of iron
- Heating of glass until it melts
- Burning a candle.
- Heating copper(II)nitrate
Marking Scheme
-
- Solid carbon (iv) oxide ,iron (III) chloride
- zinc oxide and nitric (v) acid
-
- Nitrogen or inert gases
- 200-160/200*100=40/200X100=20%
- Brown copper turnings turned black copper(II) oxide
- copper +Oxygen ---------> Copper (II) oxide
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- Simple distillation
- chromatography
- Sublimation
- Fractional distillation
-
- Hydrogen
- upward delivery/download displacement of air
Hydrogen gas is less denser than air - Zinc +dilute hydrochloric acid ---------->zinc chloride +hydrogen gas
-
- Formation of an insoluble coating layer of calcium sulphate that prevents further reaction from taking place
- Nitric (v) acid oxidises hydrogen gas formed to water
- Acts as a drying agent
- Concentrated sulphuric (vi) acid
-
- Magnesium + Oxygen -------->Magnesium Oxide
- Magnesium + nitrogen --------> Magnesium nitride
-
- Hydrogen gas
- it is basic in nature
- Calcium + water ---------> Calcium hydroxide +hydrogen gas
- A white precipitate will be formed.
-
- Electrons
Protons
Neutrons - Atoms have equal number of protons and electrons.Protons are positively charged while electrons are negatively charged thus electrically neutral.
-
- 34-18=16
- 2.8.6
- Period 3-has three occupied energy levels
Group VI-has 6 electrons in the outermost energy level
- Electrons
-
- To generate steam
- Magnesium + steam → Magnesium oxide + hydrogen gas
- Iron + steam → Tri-iron tetra oxide + hydrogen gas
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- Hydrated iron (III) oxide
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- Set up(i).This is because iron is more reactive than copper hence iron reacted with water. and oxygen.
- Sacrificial protection
- Painting cuts off oxygen gas and moisture from coming into contact with iron metal.
-
- To hold the crucible during heating
- Used for drying or keeping substances free from moisture.
- Used for even distribution of heat when heating substances in beakers or flasks.
-
- Sodium peroxide
- Sodium peroxide + water -------->sodium hydroxide + oxygen gas
- Using a glowing splint.Oxygen relights a glowing splint.
- Used in hospitals by patients with breathing difficulties.
Used by deep sea divers and high mountain climbers.
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- A liquid suspected to be water turns white anhydrous Copper (II) sulphate to blue hydrated copper (II) Sulphats turns blue Cobalt (II) chloride papper to pink
- The purity of water can be tested by checking whether it boils at 100 oC
- The product from stinging nettle plant is acidic hence aqueous ammonia solution being basic neutralizes the acidic product
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- Magnesium is more reactive than lead hence has a higher affinity of oxygen.It reduces lead (II) oxide to lead.Lead is less reactive than Magnesium thus can not displace oxygen in Magnesium Oxide.
- Magnesium + lead (II) oxide ------- Magnesium Oxide + lead
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- Magnesium
- Lead
- Redox reaction
-
- Physical
- Chemical
- physical
- Chemical
- Chemical
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