Chemistry Matters for G.C.E. ‘O’ Level Textbook Answers
Chapter 2
Chapter 2
Measurement and Experimental Techniques
Answers to Textbook Exercises Quick Check (page 26) 1.
35.2 cm3 2. (a) Burett ette (b) Pipette
Quick Check (page 28) Ammonia, chlorine and hydrogen chloride are soluble in water. Soluble gases cannot be collected by displacement of water.
Test Yourself 2.1 (page 29)
mixture of methane and water vapour
fused calcium chloride
Exercise 2 (page 30) Foundation 1. A 3.
2. C
(a) 100 cm3 measuring cylinder (b) 50 cm 3 gas syringe (c) 50 cm 3 burette (d) 100 cm 3 beaker (e) Watch glass (f) Test tube
Challenge 1.
(a) (Possible answers) – To investigate if taking tablets (meant to relieve indigestion) with alcohol would affect the speed of action by the tablets. – To investigate if the addition of alcohol slows down the reaction between indigestion tablets and water / acid.
Chemistry Matters for G.C.E. ‘O’ Level Textbook Answers
Chapter 2
(b)
balloon
conical flask
mixture of alcohol and water indigestion tablet
Variable to vary: volume of alcohol added to reaction mixture Variables to keep constant: volume of water : total mass of indigestion tablets Over a fixed time, the bigger the balloon inflates, the greater the amount of CO 2 formed. That is, the more indigestion tablets has reacted. If the balloon is inflated less when more alcohol is added, it shows alcohol decreases the speed at which the tablets work. (i.e. react with water.) 2.
(a) (i)
gas syringe dropping funnel concentrated ammonia solution
Chemistry Matters for G.C.E. ‘O’ Level Textbook Answers
Chapter 2
(b) ammon ia
gas jar
delivery tube ammonia
Critical Thinking (page 31) 1. • • • •
List should include: Purity of reactants Conditions of the reaction — e.g. temperature and concentration Purification of products Method for checking for consistency of colour
2. Reaso Reasons ns shou should ld inc includ lude: e: Easier to control the conditions Cost of extracting the natural substances greater than synthetic raw materials Greater quantities of natural substances required compared to the known amounts of synthetic materials required Natural substances may only be available seasonally • • •
