Units and Dimensional Analysis

Chapter 3 - Goals 1. Know and understand the metric system. 2. Be able to use units in performing mathematical operations. 3. Know and be able to convert within and between measurement systems. 4. Know and be able to use Dimensional Analysis. 5. Know and understand density and temperature 6. Be able to calculate percent error.

Metric versus English… English: 12 inches = 1 foot Metric: 10 mm = 1 cm English: 5280 feet = 1 mile Metric: 1000 m = 1 km

Measurement Length Mass Temperature Time Amount of substance Electric currentAmpere (amp) Luminous intensityCandela (cd) SI system (metric) Base Units

A little on multiple dimensions… The SI base unit for volume is the You may be asked to solve problems involving this. For example: Calculate the volume of a steel cube with a side that measures cm. Give your answer in cm 3 and m 3.

Practice 2 For example: You put 5.00 cm 3 of oil onto the surface of a lake. The oil spreads to occupy an area of 200 m 2. What is the thickness of the layer of oil? Give your answer in cm.

Non SI units Volume Energy  Note… different than a Calorie 

Derived Units Speed:, Density: Volume:

Terms to know… Mass: Weight: Area: Volume: Density:

Metric Prefixes You should know: Kilo Centi Milli Micro Nano Pico Mega And how they modify the base unit Larger i.e kg Smaller i.e cg Smaller i.e mg Smaller i.e μg Smaller i.e ng Smaller i.e pg Larger i.e Mg

Conversions Method 1: ladder (number line) Method 2: ratios Method 3: unit conversion

The Number Line MegaKilo Base unit MilliMicroNano Pico Centi 10 -2

MegaKilo Base unit MilliMicroNano Pico Centi Convert: mg to g

MegaKilo Base unit MilliMicroNano Pico Centi Convert: ks to ns

Solve… 4 x 6 x 7 x 3 x 2 6 x 9 x 8 x 2 x 2 a x b x 2 x c x 4 6 x 12 x b x a x 4

Plan… Convert Unit Conversion/Dimensional Analysis Convert: ks to ns

Unit Conversion/Dimensional Analysis Convert: ks to ns

Unit Conversion/Dimensional Analysis How many mg are in lb.

Convert 7.00 miles per second into meters per day.

Density Common ratio used in chemistry Physical property of a substance SI units: kg/m 3 Solid g/cm 3 Liquid g/mL Gas g/L Can change due to temperature and/or pressure changes

Density 1.Find the density of a piece of metal with a volume of 2.7 cm 3 and a mass of 10.8 g. 2. Determine the mass of an object with a density of 0.24 g/cm 3 and a volume of 2 cm 3.

Density as a conversion factor Ethanol has a density of g/mL. Use this to determine: The number of grams in mL of ethanol The number of L in E4 g of ethanol

Percent Error Percent error: how far from the true answer your data is, expressed as a percent. Percent error = X 100

Temperature Scale of Amount of Scales Kelvin Celsius Fahrenheit

Conversions o C to o F o F = 1.8( o C) + 32 o C to K K = o C

Determine the Celsius temperature if the Fahrenheit temperature is

Convert Copper boils at o C. What is this temperature in o F

Convert What is the boiling point of copper in K?