Dimensional Analysis and Density

Warm - Up Which side of a ruler should you use to measure – English or metric? Why? How many decimals places past the decimal point can you read a ruler? How do you read a graduated cylinder? How many decimal places can be in your measurement of a graduated cylinder? How many decimal places can be in your measurement of a beaker or a flask? In general, what is an acceptable percent error for a lab?

Objective Today I will be able to: Apply dimensional analysis to real – life situations Calculate density be completing a lab

Homework Study for metric system/ dimensional analysis and accuracy and precision quiz Dimensional analysis practice

Agenda Warm – Up Density Notes Density Lab Baking and Dimensional Analysis Scenario Exit ticket

Density

Density Mass – quantity of matter a body possess (constant) Weight – force of attraction of the earth for a body (gravitational attraction) (variable)

Introduction Matter occupies space, and therefore, has volume Density = mass/volume - Units are g/ml (liquids) and g/cm3 (solids)

What is Density? Density reveals how tightly the molecules composing the matter are packed and how heavy the molecules are Compared to the liquid they are in, less dense materials float, more dense sink Substances are often IDed by their density, as it is rare for two substances to have the same density

Density and States of Matter Solids – composed of tightly packed molecules, low kinetic energy, high density (Iron)

Density and States of Matter Liquids – more loosely packed than solids, density less than solids (water)

Density and States of Matter Gases – molecules are all over the place, density less than solids and liquids (air)

Calculating Density Remember, Density = mass/volume Mass is determined using a scale Volume is calculated several different ways

Finding Volume To find the volume of a liquid, use a graduated cylinder Make sure to read the bottom of the meniscus

Finding Volume Length x Width x Height Volume of a regular object, such as a wooden block

Finding Volume Water Displacement Method - Read the initial volume of water in a graduated cylinder - Place object into cylinder - Read the final volume of water - Final – Initial = Volume of the object

Exit Ticket Which has a greater mass, 6.00 g of lead or 7.00 g of styrofoam? Which occupies a greater volume, 5.00 cm3 of lead or 5.00 cm3 of styrofoam? Which occupies a greater volume, 5.00 g of lead or 5.00 g of styrofoam? Which occupies a greater volume, 9.00 g of lead or 50.0 g of styrofoam? Which occupies a greater volume, 50.0 g of lead or 9.00 g of styrofoam? Styrofoam, neither, styrofoam, styrofoam, can’t tell