KCSE CHEMISTRY QUESTIONS AND ANSWERS PER TOPIC
Use the information below to answer the question that follows
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(a) A few drops of freshly prepared iron (II) sulphate solution were added to potassium nitrate solution in a test – tube. Concentrated sulphuric acid was then carefully added to the mixture. State the observation that were made
(b) Write an equation for the reaction that occurs when solid potassium nitrate is strongly heated
Use the cell representation below to answer the questions that follow
In an attempt to prepare sulphur dioxide gas, dilute sulphuric acid was reacted with barium sulphuric. The yield of sulphur dioxide was found to be negligible explain
The pressure of nitrogen gas contained in a 1dm3 cylinder at -196°C was 107 Pascals.
Calculate the: a) Volume of the gas at 25°C and 105 Pascals. b) Mass of nitrogen gas(Molar volume of gas is 24dm3, N = 14.0)
Complete the table below by writing the product formed at the electrodes during the electrolysis of the electrolytes given in the table.
Aluminium oxide reacts with both acids and bases.
a) Write an equation for the reaction between aluminium oxide and hydrochloric acid. b) Using the equation in (a) above, calculate the number of moles of hydrochloric acid that would react completely with 153.0g of aluminium oxide. (AL = 27.0, 0= 16.0)
Hydrate cobalt(II) chloride exists as pink crystals and anhydrous cobalt(II) chloride is a blue powder. Describe a laboratory experiment that can be used to show that the action of heat on hydrated cobalt(II) chloride is a reversible reaction.
Draw the structures and give the name of the three alkaline having molecular formula C5H10
What is the name given to each of the following:
a) What is meant by the terms: i. element ii. atomic number
b) The formula for a chloride of titanium is TiCl3. What is the formua of its sulphate?
ANSWERS
(i) Element — substance that consists of one type of atoms.
(ii) Atomic number — number of protons in an atom. Ti3(S04)2
a) Distinguish between a deliquescent and a hygroscopic substance.
b) Give one use of hygroscopic substance in the laboratory.
ANSWERS
(a)Deliquescent - a substance that absorbs water from the atmosphere and changes into a solution.
Hygroscopic — a substance that absorbs water from the atmosphere but just becomes wet. (b)drying agent. D gm of potassium hydroxide were dissolved in distilled water to make 100cm3 of solution. 50cm3 of the solution- required 50cm3 of 2 M nitric acid for complete neutralization. Calculate the mass D, of potassium hydroxide (KOH)(aq) + HNO3(aq) →KNO3 (aq) + H2O (I) Relative formula mass of KOH = 56
State the observation that would be made when a piece of sodium metal is placed in samples of:
Pentane: __________ Pentanol: __________
The table below shows the solubility of a salt at various temperatures
What would happen if a sample of a saturated solution of the salt at 400C is heated to 800C. Explain
Write the formula of sulphide of an element C, whose atomic number is 5. (C is not the actual symbol of the element)
What type of bond is formed when lithium and Fluorine react? Explain
(Atomic numbers: Li = 3 and F = 9)
Starting with red roses, describe how;
(i) a solution containing the red pigment may be prepared (ii) the solution can be shown tobe an indicator.
ANSWERS
(i)Crush the roses with a suitable solvent Filter to obtain pigment
(ii)Add pigment to an acid . It turns read
Sulphur dioxide and nitrogen dioxide react as shown in the equation below
SO2(g) + NO2(g) → SO3(g) + NO(g)
(i) Using the oxidation numbers of either sulphur or nitrogen, show that this is a redox reaction
(ii) Identify the reducing agent
4.76g of liquid ammonia and 4.76g of liquid nitrogen were each allowed warming up and hanging into gas at warm temperature and pressure. Relative atomic masses: H=1.0 and N=14.0. Using the data given above, explain which gas occupied the greater volume.
State and explain the observation that would be made when a few drops of concentrated sulphuric acid are added to a small sample of hydrated copper (II) sulphate
Study the flow chart below and answer the questions that follow
(a) Name:
Aluminium metal is a good conductor and is used for overhead cables. State any other two properties that make aluminium suitable for this use.
ANSWER
(a) Energy of the activated energy Therefore more molecules will take part in effective collision. Or Energy of the activated/intermediate complex of the unanalyzed reaction
(b) Catalyst lowers the activation energy therefore more molecules will take effective collision |
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