Physical Properties & Density

Physical Properties How would you describe someone or something? How would you describe someone or something? The weight, height, length, eye color, hair color, etc. would be good items to use to describe someone. The weight, height, length, eye color, hair color, etc. would be good items to use to describe someone. It is easy to identify chemicals, compounds and elements based on their physical properties also. It is easy to identify chemicals, compounds and elements based on their physical properties also. These include color, odor, and state of matter to name a few. These include color, odor, and state of matter to name a few.

Density Another physical property that can be used is density. Another physical property that can be used is density. Density is a measure of the relationship between mass and the volume it occupies. Density is a measure of the relationship between mass and the volume it occupies. Think of it like using weight and height. Think of it like using weight and height.

Density Units Density can be defined as the unit mass per unit volume. Density can be defined as the unit mass per unit volume. Density = Mass/Volume Density = Mass/Volume Density is recorded as g/ml. Density is recorded as g/ml. Mass is measured in g. Mass is measured in g. Volume is measured in ml. Volume is measured in ml.

Density Calculations To perform a density calculation: To perform a density calculation: Determine if it is a density problem. The problem should include statements for mass and volume and density. Determine if it is a density problem. The problem should include statements for mass and volume and density. Read the word problem. Read the word problem. You will need to calculate one of the three terms but the other two should be given (# unit). You will need to calculate one of the three terms but the other two should be given (# unit). Write down the mathematical formula for density. Write down the mathematical formula for density. Plug in the given. Plug in the given. Convert to the correct units if necessary. Convert to the correct units if necessary. Solve the problem Solve the problem Let’s look at some examples Let’s look at some examples

Density What is the density of 5 g of tin that has a volume of 1.2 ml? What is the density of 5 g of tin that has a volume of 1.2 ml? Density, = Mass, / Volume, Density, = Mass, / Volume, g/ml = g / ml g/ml = g / ml ? g/ml = 5 g / 1.2 ml ? g/ml = 5 g / 1.2 ml 4.2 g/ml 4.2 g/ml

Density What is the volume of 5 g of tin that has a density of 4.6 g/ml? What is the volume of 5 g of tin that has a density of 4.6 g/ml? Density, = Mass, / Volume, Density, = Mass, / Volume, g/ml = g / ml g/ml = g / ml 4.2 g/ml = 5 g / X ml 4.2 g/ml = 5 g / X ml

Density 4.6 g/ml = 5 g / X ml 4.6 g/ml = 5 g / X ml Get the unknown by itself. 1.Multiply both sides by X ml to cancel it off the bottom. 4.6 g/ml * X ml = ( 5 g / X ml) * X ml 4.6 g/ml * X ml = ( 5 g / X ml) * X ml 4.6 g/ml * X ml = 5 g 4.6 g/ml * X ml = 5 g

Density Get the unknown by itself. 2.Divide both sides by 4.6 g/ml to finish getting the unknown alone. 4.6 g/ml * X ml = 5 g 4.6 g/ml * X ml = 5 g (4.6 g/ml * X ml)/ 4.6 g/ml = 5 g / 4.6 g/ml (4.6 g/ml * X ml)/ 4.6 g/ml = 5 g / 4.6 g/ml

Density X ml = 5 g / 4.6 g/ml X ml = 5 g / 4.6 g/ml If at this time while doing other problems, if the units don’t match, you are wrong and need to restart the problem X ml = 1.2 ml X ml = 1.2 ml Grams cancel out and you are left with ml. Try the math.

Buoyancy and Density One factor that density controls is floating and sinking. One factor that density controls is floating and sinking. Objects float and sink because of their density. Objects float and sink because of their density.  Compounds that are MORE dense than water sink  Compounds that are LESS dense than water float The density of water is 1.0 g/ml. The density of water is 1.0 g/ml. The density of cork is 0.34 g/ml. The density of cork is 0.34 g/ml. The density of lead is 13.9 g/ml. The density of lead is 13.9 g/ml.

Does metal float or sink in water? Does metal float or sink in water? Sink. Sink. Look at lead. Look at lead. What is the density of lead? What is the density of lead? Is it less or more dense than water? Is it less or more dense than water? More More Compounds that are more dense than water sink. Compounds that are more dense than water sink. Name some other items that will sink in water. Name some other items that will sink in water. Buoyancy and Density

Does cork float in water? Does cork float in water? Yes. Yes. Look at cork. Look at cork. What is the density of cork? What is the density of cork? Is it less or more than water? Is it less or more than water? Compounds that are less dense than water float. Compounds that are less dense than water float. Name some other items that will float in water. Name some other items that will float in water.