Chem 136-lab B 6i91k

Density and Specific Gravity Pre-Lab Study Questions

1. What property of oil makes it float on water? Water is denser than oil. Water sinks and oil rises. 2. Why would heating the gas in an air balloon make the balloon rise? As air is heated, it becomes less dense than the surrounding cooler air. 3. What is the difference between density and specific gravity? One is a ratio of the other. Specific gravity is a measure of a density. 4. How does a graph help us interpret scientific data?

It allows you to see a change in the data and use it to predict possible changes. A. Density of a Solid (Use the “density of a solid demonstration” to collect data.)

A.1 Mass of the solid ____18g_______ A.2 Volume of the solid by displacement Initial water level (mL) _____20_______ Final water level with solid (mL) ______32_______ Volume of solid (mL) ___12__________ A.3 Calculating the density of the solid ___1.5g/mL________ Show calculations 18g/12mL

Questions and Problems (Show complete setup)

Q.1 An object made of aluminum has a mass of 8.37 g. When it was placed in a graduated cylinder containing 20.0 mL of water, the water level rose to 23.1 mL. Calculate the density and specific gravity of the object. Density = 8.37g/3.1mL = 2.7 g/mL Specific Gravity = 1

B. Density of a Liquid (Use the “Sugar-Water Experiment” to collect data) B.1 Volume of Liquid Type of liquid sugar water Volume (mL) __3.3 mL_________ B.2 Mass of Liquid Mass of beaker ____50g__________ Mass of beaker + liquid ______75g________ Mass of liquid ___25g_________ B.3 Density of a Liquid Density ___7.58g/mL_________ (Calculations for density) 25g/3.3mL

C. Specific Gravity

C.1 Specific gravity ____7.58__________ (Show calculations, calculated from B.3)

7.58g/ml / 1.00

Questions and Problems (Show complete setups.)

Q.2 What is the mass of a solution that has a density of 0.775 g/mL and a volume of 50.0 mL? 50 * 0.775 = 38.75g

Q.3 What is the volume of a solution that has a specific gravity of 1.2 and a mass of 185 g? 1.2 * 185 = 222mL