Questions and Answers
Match the following physical properties of measurement with their corresponding SI units and examples of measuring apparatus:
Time = Second (s), Digital stopwatch Mass = Kilogram (kg), Beam balance Temperature = Kelvin (K), Gas syringe Volume = Cubic metre (m³), Burettes Length = Metre (m), Measuring tape
Which measuring apparatus is used to measure accurate fixed volumes?
A measuring cylinder measures volumes to the nearest 0.05 cm³.
False
What is the function of downward delivery in gas collection methods?
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A burette measures a range of volumes to the nearest ______.
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What is the meniscus in relation to measuring liquids?
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Study Notes
Measurements in Experimental Chemistry
- Common physical properties measured in chemistry include time, mass, temperature, volume, and length.
- Standard International (SI) units and symbols for these properties are:
- Time: Second (s)
- Mass: Kilogram (kg)
- Temperature: Kelvin (K)
- Volume: Cubic metre (m³)
- Length: Metre (m)
Measuring Apparatus
- Time can be measured using digital stopwatches, mechanical stopwatches, and electronic balances.
- Mass is measured using beam balances and digital laboratory thermometers.
- Volume measuring devices include burettes and pipettes.
- Length measuring tools consist of metre rules and measuring tapes.
Measuring Liquid Volume
- Burette: Precision measuring device for small volumes, accurate to 0.05 cm³.
- Measuring Cylinder: Measures a range of volumes with an accuracy of 0.5 cm³.
- Pipette: Used for fixed and accurate volumes; common sizes include 20 cm³ and 25 cm³.
- Volumetric Flask: Ideal for measuring large fixed volumes, typically 100 cm³ or 250 cm³.
Measuring Gas Volume
- Avoid parallax error by ensuring eye level is aligned with the liquid meniscus when reading measurements.
- The meniscus is the curved surface of the liquid in a measuring instrument.
Collection of Gases
- Gases can be collected using three primary methods:
- Displacement of air
- Displacement of water
- Gas syringe
-
Displacement of Air: Suitable for collecting gases with densities either higher or lower than air.
- Downward Delivery: Effective for gases denser than air, prevalent in certain chemical reactions.
Factors Influencing Method Choice
- The solubility of the gas and its density are key considerations in selecting the appropriate gas collection method.
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Description
Test your understanding of measurements and physical properties in experimental chemistry from Unit 1. Explore various measuring apparatus and their corresponding SI units. This quiz covers fundamental concepts essential for practical experiments in chemistry.
