Mathematical Foundations in Chemistry

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.

Measuring Instruments The Ruler In science is the American or metric system used? Metric ALWAYS

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?

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

Proper Measurement Inaccurate measurement when looking from top. Inaccurate measurement when looking from bottom. Proper measurement when measuring at eye level with meniscus.

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

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

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