Thursday, April 24, 2008 - 4B

Described using pictures and steps how to do the Density 3 lab - Density of liquids.

If you use a red based 10 mL graduated cylinder, the measurements are off by 0.15 mL.
Actual volume = volume read from grad cylinder - 0.15 mL.

If you use this grad cylinder for measuring the density of liquids you MUST make this correction.

Procedure:
1. Zero the electronic balance.
2. Place the 5 mL graduated cylinder on the balance and read the mass of just the graduated cylinder
3. Go to the table with the beakers of liquid and put exactly 5 ml of liquid into the graduated cylinder using a pipette. Do not bring the beakers over to the electronic balances in case of spills.
4. Re-zero the balance and put the graduated cylinder with liquid on the balance. Read the mass of the graduated cylinder + liquid.
5. Find the mass of the liquid by subtracting the mass of the graduated cylinder from the mass of the grad cylinder plus liquid.
6. Find the density using density = mass/volume

Students were given time to finish Density Lab 2, then do Density Lab 3. When done with both labs, students posted their density values on the board. They redid any I thought were too far off.

When done with all labs, students handed in both labsheets and worked on the homework packet of density problems.