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Measurements in Chemistry Science in Focus, Chemistry OLevel, 2 nd Edition, Chapter 1

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Presentation on theme: "Measurements in Chemistry Science in Focus, Chemistry OLevel, 2 nd Edition, Chapter 1"— Presentation transcript:

1 Measurements in Chemistry Science in Focus, Chemistry OLevel, 2 nd Edition, Chapter 1

2 What are we going to learn this Chapter? Name appropriate apparatus for the measurement of time, temperature, mass and volume. State the level of accuracy needed when using common measuring apparatus. Suggest suitable apparatus for simple experiments State the purpose of data logging and list examples of its uses.

3 Apparatus for Measurement Stopwatch measures time Accuracy: Nearest second Electronic balance measures mass Accuracy: Up to g Triple beam balance measures mass Accuracy: Nearest 0.1g

4 Apparatus for Measurement Thermometer measures temperature Accuracy: Nearest 0.5 o C (either end with.0 or.5 o C) Gas Syringe measures volume of gas produced Accuracy: Nearest 1 cm 3

5 Apparatus for Measurement Measuring Cylinder Holds either 100 or 250 cm 3 Accuracy: Nearest 1 cm 3 Measuring Volume of Solution Burette Holds 50 cm 3 Accuracy: Nearest 0.1 cm 3 Pipette Holds 10.0, 20.0 or 25.0 cm 3 Only measures fixed volumes.

6 Apparatus for Measurement 1.Is it correct to record a thermometer reading of 24.7 o C? 2.What apparatus can we use to measure 80 cm 3 of solution? 3.What apparatus can we use to add 20.0 cm 3 of acid solution drop by drop to an alkali solution? 4.What apparatus can we use to measure out 22.4 cm 3 of solution?

7 Apparatus for Experiments Flammable liquid is heated using a water – bath. Heating of a Flammable Liquid It can be used to find the boiling point of the flammable liquid. If the boiling point of the liquid is higher than water, then we use oil instead of water (oil- bath). (Learn how to draw)

8 Apparatus for Experiments Use a sulfuric acid of known concentration. Pipette a fixed volume of it. Add alkali solution bit by bit to it and find the volume needed to neutralized the acid completely Use the alkali volume measured to neutralize the acid and find the concentration of the alkali. Titration (Important when you learn acid and base calculations)

9 Apparatus for Experiments Change in Mass during a Reaction Used when gas is produced during a reaction. As gas escapes, the mass of the substances in the flask decreases. By measuring how fast the mass decreases, the speed of the reaction is determined.

10 Apparatus for Experiments Volume of Gas during a Reaction Used when gas is produced during a reaction. As gas escapes, it fills the space in the gas syringe. By measuring how fast the syringe is filled, the speed of the reaction is determined.

11 Apparatus for Experiments What are the two changes you would make to this set-up if you want to warm the flammable liquid? Explain. Heat Flammable liquid Stopper

12 12 Volumetric flask To measure fixed volume of large amount of liquid accurately. (accurate to 0.1 ml) e.g ml, ml

13 Apparatus for Experiments Collection of Gas Gases are collected for industrial and experimental uses after they are prepared. Common gases are hydrogen, oxygen, ammonia, chlorine and carbon dioxide. The method chosen to collect them depends on their solubility in water and density compared to air.

14 Apparatus for Experiments Displacement of water For gases insoluble in water, eg. oxygen, hydrogen, carbon dioxide (Learn how to draw)

15 Delivery tube Gas Gas jar

16 Apparatus for Experiments For gases soluble in water and less dense than air, eg. ammonia Upward delivery Special note: hydrogen (Learn how to draw)

17 Delivery tube Gas jar Gas

18 Apparatus for Experiments Downward delivery For gases soluble in water and denser than air, eg. chlorine, hydrogen chloride, sulfur dioxide Special note: carbon dioxide (Learn how to draw)

19 Delivery tube Gas jar Gas

20 Apparatus for Experiments Drying of gases (Removing water)

21 1.Hydrogen, carbon dioxide, ammonia and chlorine are produced from a factory. They are passed through a water tank and then concentrated sulfuric acid and lastly collected by downward delivery. a.What is the use of the water tank? b.What is the use of concentrated sulfuric acid? c.What gas is collected at the end? Explain. Apparatus for Experiments

22 Data logging is used for Temperature changes Change in volume of gas produced Change in mass during reaction Change in pH as acid reacts with alkali Apparatus for Experiments


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