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Published byAlvin Wheeler Modified over 9 years ago
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Mathematical Foundations in Chemistry
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Measurement A chemist must know how to properly use all measuring devices. Must know how to determine the most precise measurement the instrument will allow.
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Measuring Instruments The Ruler In science is the American or metric system used? Metric ALWAYS
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Measuring Instruments Graduated Cylinders - Liquids A graduated cylinder is used to measure the volume of a liquid. – This is a 100 milliliter graduated cylinder (GC) – How would you read the volume of this liquid?
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Properly Measuring a Liquid Because of a liquid’s adhesive property, a lens shaped meniscus forms at the surface of the liquid. When measuring liquids, measure from the bottom of the meniscus. MeniscusALWAYS
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Proper Measurement Inaccurate measurement when looking from top. Inaccurate measurement when looking from bottom. Proper measurement when measuring at eye level with meniscus.
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Measuring Instruments The Thermometer A THERMOMETER is used to measure the TEMPERATURE of a substance – Temperature is a measure of how much KINETIC ENERGY the molecule of a substance have. – KINETIC ENERGY is the energy of MOTION Therefore: THERMOMETERS measure how much ENERGY is being given off due the MOVEMENT of molecules
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Using a Thermometer When you look at a regular outside bulb thermometer, you'll see a thin red or silver line that grows longer when it is hotter. The line goes down when colder. This liquid is sometimes colored alcohol but can also be a metallic liquid called mercury. Both mercury and alcohol grow bigger when heated and smaller when cooled. Increasing Temperature Decreasing Temperature Molecules Moving Faster Molecules Moving Slower
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How to Measure When measuring we always record the actual values that we see. – 29 Degrees We ESTIMATE the next place value. – I would estimate that the red line is 0.1 degree above 29 degrees. Therefore this Thermometer reads 29.1 degrees
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