Calculating Density Recap the factors affecting density Formula for calculating density Practicing the calculations

What is Density? Density is the mass per unit volume of a substance Density is function of MASS & VOLUME

What is Density? Remember the definition for Matter: Matter is anything that has mass and takes up space Therefore, to find density of matter we need to know the mass of the substance, and the volume of space it takes up

Formula The formula for calculating density is: Density (d) = Mass (M) Volume (v) or the abbreviated version is d = M v

Units The units for density change depending on whether you are looking at a solid or a fluid Units for solids are mass = g volume = cm³ therefore density = g / cm³ Units for liquids are mass = g volume = ml therefore density = g / ml

Finding Mass Finding mass is as simple as weighing the object using a scale

Finding Volume Finding volume can be a little bit more tricky If the object your measuring is a regular shape (i.e. cube, sphere, prism) you can measure the sides and calculate If it is an irregular shape (i.e. strawberry, person, jeep) you need to use a capacity measurement by dipping the object in water and seeing how much water volume was displaced 1 ml = 1 cm³

Finding Volume

Finding Density Write out the practice question first: A gold coin has a mass of 33.6 g and the volume was calculated to be 2.1 cm³ What is the density of this gold coin? Don’t forget to start by stating the equation you are going to use and only one equal sign per line d = M v d = 33.6 g / 2.1 cm³ d = 16 g/cm³ (solids mean cm³)

Finding Density Write out the practice question first: a small glass holds 250 ml of juice. We find that the juice weighs 350 g. What is the density of the juice? Don’t forget to start by stating the equation you are going to use and only one equal sign per line

Finding Density Write out the practice question first: a small glass holds 250 ml of juice. We find that the juice weighs 350 g. What is the density of the juice? Don’t forget to start by stating the equation you are going to use and only one equal sign per line d = M v d = 350 g / 250 ml d = 1.4 g/ml (liquid means ml)

Finding Density Try this one your self: A brick has a mass of 750 g and a volume of 250 cm³. What is the density of the brick? Don’t forget to start by stating the equation you are going to use and only one equal sign per line What is your answer ?

Finding Density Try this one your self: A brick has a mass of 750 g and a volume of 250 cm³. What is the density of the brick? Don’t forget to start by stating the equation you are going to use and only one equal sign per line d = M v d = 750 g / 250 cm³ d = 3 g/cm³ (solids mean cm³)

Finding Density Try this one your self: Some mysterious liquid was found in a garbage can, it had a mass of 450 g but only took up a volume of 75 ml. What is the density of the liquid? Don’t forget to start by stating the equation you are going to use and only one equal sign per line What is your answer ?

Finding Density Try this one your self: Some mysterious liquid was found in a garbage can, it had a mass of 450 g but only took up a volume of 75 ml. What is the density of the liquid? Don’t forget to start by stating the equation you are going to use and only one equal sign per line d = M v d = 450 g / 75 ml d = 6 g/ml (liquid means ml)

Your Assignment Your assignment for today is: You are being given a worksheet with density questions on it Your job is to complete this sheet so that it can be marked in the next class In some of the questions you may need to calculate volume 1 st so you need to know the equations to find volume You may also need to do some comparison of densities and graph them

Formulas Here are a couple of formulas you will need: Density = Mass / Volume Volume Rectangle = Base x Width x Height Volume Sphere = 4 x 3.14 x r³ 3