Determining the Density of Plastics

Determining the Density of Plastics

1) Introduction
⦁ a) Purpose: Determine density of different plastics
⦁ b) Hypothesis: If density is related to the ratio of mass to volume, then density can be calculated by using the formula D=M/V.
i. c) Background: Density is the physical property that can be used to help identify substances. D=M/V. mass= found using a balanc and labeled in grams and volume=graduated cylinder or taking ( lxwxh ) measured in mL or cm3

2) Materials
⦁ a) List
-graduated cylinders
-balance
-plastic strips ( polystyrene, polythylene, polyvinyl, & unknown plastic)
-salt water
-rubbing alcohol water ⦁ b) Safety
-closed toed shoes
-safety glasses
-tie long hair

3) Procedure
⦁ a) Part 1:
i. safety glasses ii. fill one vile/graduated cylinder 3/4 full iii. fill another cylinder 3/4 of saltwater iv. fill another cylinder 3/4 of rubbing alcohol
v. place one of each type of plastic strips in the graduated cylinder vi. invert the graduated cylinder vii. wait and see which strip will float or sink viii. record the results
⦁ b) Part 2: vii. take 10 polyvinyl chloride strips and find the mass viii. fill the graduated cylinder 3/4 full of water ix. record level in graduated cylinder
x. drop all 10 plastic strips into the graduated cylinder and record xi. repeat all other plastics

4) Data & Calculations
⦁ a) Data
Sample Water Sodium Chloride Rubbing Alcohol
------------ ----------- ---------------------- ----------------------
-PS Sink Float Sink
-HDPE Float Float Sink
-PVC Sink Sink Sink
-Unkown Sink Float Sink

# Plastic Strip Mass(g) Volume before (mL) Volume after (mL) Change in Volume
------------------- ------------ -------------------------- ------------------------- -------------------------
-PS 2.91 10 13.5 3.5
-HDPE 2.11 10 12.5 2.5
-PVC 2.55 10 12.5 2.5
-Uknown 2.63 10 13 3

⦁ b) Calculations:
i. PS-