Which factor: temperature or salinity do you think will play a bigger role in determining the speed of the solution?

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1 Accel Keeping Current Name: Purpose: To examine the role of density in currents. Hypothesis Which will make a fast flowing current? You will test the ability of four solutions to travel through tap water. The four solutions are 1) cold, salty water 2) cold, fresh water 3) warm, salty water 4) warm, fresh water. Which solution do you think will travel fastest through the tap water? Why? Which factor: temperature or salinity do you think will play a bigger role in determining the speed of the solution? Procedure: 1. Take the mass of the graduated cylinder and record its mass above the chart. Use the same balance and graduated cylinder throughout the investigation. Be sure that the outside is dry before measuring its mass. Do not try to dry out the inside, just shake out as much water as possible. Empty graduated cylinder mass 2. Check that the hose on the bottom of the tube is tightly clamped. It may be necessary for one person to hold the tube steady especially while filling the tube with water. Fill the tube with tap water from the cold faucet 2/3 full (to the fill line) 3. Use a thermometer to record the temperature of solution 1 (cold salty water). Write this in the chart below in degrees C. 4. Then add/measure exactly 50 ml of solution 1 into your graduated cylinder and use the scale to get the mass of the solution in the graduated cylinder. Subtract the empty graduated mass from this new mass to get the mass of just the solution. Record the mass of the solution in the chart. mass of filled graduated cylinder - mass of empty graduated cylinder = mass of solution 6. Calculate the density of the solution and record it in the chart (use proper units) 7. You will now time how long it takes the colored solution to move through the tap water. One person should pour while another watches the time and a third person supports the tube and prevents spills. Begin timing as soon as the water touches the surface of the tap water; stop when it first reaches the bottom. 8. Once you timed the solution traveling through the tap water, you may empty the tube by removing the clamp to drain the water into the sink. 9. Once again secure the clamp and fill the tube with tap water from the cold water faucet. Get 50 ml of solution 2 (cold, fresh) and measure its temperature and mass. Calculate its density. Then time how long it travels through the tap water. Repeat the experiment until all 4 solutions have been tested.

2 Solution temp mass of solution (full-empty cylinder) 1 cold, salty 2 cold fresh 3 warm salty 4 warm fresh Density (mass/volume) time The above graph shows the general relationship between salinity and temperature. The diagonal lines are the densities. Use your information from the data table to determine the salinity of the cold salty water (if it is off the chart, then simply indicate what it is less than or greater than): Why did the solutions move through the tube at different rates? Which current moved fastest? Which factor in THIS experiment: salinity or temperature had the greatest effect on the rate of movement? (it may or may not match reality) Use your results to support your statement.

3 Based on your experiments what would you expect deep water currents to be like in terms of salinity (saltiness) and temperature? Where in the world would conditions be suitable to create these deep currents? How might a sudden influx of freshwater influence the ocean currents? Occasionally turbidity currents occur in submarine canyons on continental slopes. This is a current made of both water and sediment. What would adding sediment do to the density of the ocean water? Therefore what can you assume about the speed of the turbidity current? Deep currents make up one part of the Global Ocean Conveyor. Why are ocean currents important what do they do and transport? (use your text, your background knowledge, and your brain to answer) Refer again to the graph of salinity, temp, and density. Look up the densities of each of the following ocean water masses (estimate if it falls between lines) by plotting the temp and salinity on the graph: Water mass name depth Temp C Salinity ppt North Atlantic Surface water Antarctic Intermediate Mediterranean Intermediate North Atlantic Deep water Antarctic Bottom Water Which water would travel the fastest? Why might the North Atlantic Surface water and Mediterranean waters have high salinities? Density g/ml

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