Accuracy of Measurements accepted value: true or correct value based on reliable source experimental value: measured by you during the experiment

Error difference between the accepted value and the experimental value take the absolute value

Error % error = error x 100 accepted value = actual – experimental x 100 actual

Error A student measures a volume as 25.0 mL but the correct volume is 23.2 mL. Calculate %error.

Density Which is heavier – a pound of popcorn or a pound of cheese? They have the same mass!! If you had equal VOLUMES of popcorn and cheese, the cheese would have more mass.

Density A cube of gold-colored metal with a 64 cm 3 volume is 980. grams. The density of pure gold is 19.3 g/cm 3. Is the metal pure gold?

Temperature The temp of an object determines the direction of heat transfer. three scales: Farenheit Celsius Kelvin

(Gabriel) Fahrenheit Scale German physicist, 1714 first to use Hg in thermometer 3 measured quantities for scale: water freezing point = 32°F water boiling point = 212°F 0°F = fp of water, salt & dry ice

Why use Hg in a thermometer? increase T of mercury, and its expansion is NOTICABLE and CONSTANT. alcohol thermometer used in Alaska because Hg will freeze!

(Anders) Celsius Scale Swedish Astronomer, 1742 centigrade (100 divisions) water fp = 0°C, water bp = 100°C uses Hg in thermometer conversion: F = 9 / 5 C + 32

(Lord William) Kelvin Scale developed in 1848 based on absolute zero = zero kinetic energy = all motion stops zero Kelvin = –273.15°C no degree sign (Kelvin units)

(Lord William) Kelvin Scale Kelvin is a theoretical scale – does not compare its temp. to the fp or bp of water. Based on lowest temperature possible – no negative numbers on scale

Compare Temperature Scales