Sea Water Sea Water DensityDensity

““Mass per unit Mass per unit volume”volume”

TEMPERATURETEMPERATUREWater molecules Water molecules

are at the are at the maximum maximum distance from distance from adjacent adjacent molecules due molecules due to hydrogen to hydrogen bonding==bonding==

Minimum Minimum

density.density.

Water makes Hydrogen Bonds

Ice (solid phase) is a crystal with maximal number of hydrogen bonds per molecule (4)

crystalline lattice configuration

Deep circulation in the Deep circulation in the AtlanticAtlantic

1. The effect of salinity on 1. The effect of salinity on density:density:Use hydrometer and thermometer to measure the density and temperature for three solution of different salinities: 10, 20, 35 ‰

Hydrometer must be floating

Determine what the theoretical density should be at a given temperature and salinity.

2: The effects of Temperature The effects of Temperature on Densityon Density

• Use 35%o water. Warm this water to 30°C. Then chill it, measuring the density along the way with 2 minute intervals.

• Remove the Remove the hydrometer between hydrometer between measurements.measurements.

30 ºC

5 ºC

3. The Effect of Ice Formation on 3. The Effect of Ice Formation on DensityDensity

1. Let ~1/3 of your sample to turn into ice.

2. Transfer the remaining liquid that does not freeze “brine” into graduate. (you need ~85 mL to float the hydrometer)

3. Measure the temperature with the thermometer and measure the density with a hydrometer at 5oC.

DO NOT STIR WITH THE THERMOMETER

DO NOT LEAVE THE THERMOMETER IN THE FLASK WHILE FREEZING

4: Temperature vs Salinity4: Temperature vs Salinity

Although not in the text, we will be setting up Although not in the text, we will be setting up the internal wave tanks again:the internal wave tanks again:

1)1) Place the divider in the center and put 2.5 Place the divider in the center and put 2.5 liters of cold (blue) fresh water in one half liters of cold (blue) fresh water in one half and 2.5 liters room temperature (red) fresh and 2.5 liters room temperature (red) fresh water in the other half.water in the other half.

2)2) Predict the outcome and then pull the Predict the outcome and then pull the divider.divider.

3)3) After the tank settles, reinsert the divider After the tank settles, reinsert the divider ~1/3 of the tank and stir the layers ~1/3 of the tank and stir the layers together.together.

4)4) Pull the divider again and answer the Pull the divider again and answer the questions. questions.

1500 ml tap water15 drops of yellow

1500 ml cold water15 drops of blue