Physical properties of water

--an informal lab

Purpose

• To measure several physical properties of water, and compare those properties to acetone and lighter fluid

Please measure and record:

1) The time it takes to deliver 10.00 ml of each liquid.

2) The mass of 10.00 ml of each liquid (by difference)

3) The number of drops of each it takes to fill a .35 ml well plate

4) The number of drops over the rim that surface tension will allow a .35 ml well to hold.

Please measure and record:5) Sketch, on graph paper, the area that a

single drop will cover when delivered to a flat surface.

6) Change in temperature that occurs when a heated marble is delivered to a 50 ml sample of each liquid. (Will be done together as a class)

7) The mass remaining of the 10.00 ml of each liquid after 1 hour

What is being measured in each case?

1)

2)

3)

4)

5)

6)

7)

What is being measured in each case?

1) Viscosity

2) Density

3) Size of each drop

4) Surface tension

5) Cohesion and surface tension

6) Specific heat capacity

7) Rate of evaporation

To start your discussion:

• Draw a Lewis diagram of each molecule:

H2O CH3COCH3 C9H20

Water Acetone Lighter fluid

• Label polar bonds—determine whether each molecule is polar or nonpolar.

• Calculate the formula mass of each compound

Discussion (1)

• Define viscosity

• How does the time relate to viscosity?

• Relate to attraction between molecules

• Relate to the size of a molecule

• List, in order, least to most viscous

Discussion (2)

• Calculate the density of each liquid using your data. Show all of your work clearly. Include units and consider significant figures.

• Relate to attraction between molecules

• List, in order, least to most dense

Discussion (3)

• How does the number of drops in .35 ml relate to the size of each drop?

• Calculate the size of a drop for each liquid using your data. Show all of your work clearly. Include units and consider significant figures.

• Relate to attraction between molecules

• List, in order, least to most volume/drop

Discussion (4)

• Define surface tension

• Convert the number of drops to volume above the rim for each liquid using your result from (3). Show all of your work clearly. Include units and consider significant figures.

• Relate to attraction between molecules

• List, in order, least to most surface tension

Discussion (5)

• Estimate the area covered by each sketch.

• Relate to attraction between molecules

• List, in order, least to most area covered by a drop.

Discussion (6)

• Define specific heat capacity (C).• Supposing that a 3.4 g marble at 90oC

gives up 200J of heat to each liquid as it cools, how is the final temperature affected by the specific heat capacity?

• Relate to motion of molecules• Relate to attraction between molecules• List, in order, least to most specific heat

capacity

Discussion (7)

• Describe the process of evaporation • Calculate the rate of evaporation, in g/min

for each liquid. Show all of your work clearly. Include units and consider significant figures.

• How does the change in mass indicate the rate of evaporation?

• Relate to attraction between molecules• List, in order, least to most evaporation in

the given time