1. Make a better Hydrometer On the front table is a variety of supplies to make a better hydrometer. Your mission will be to create a better hydrometer to measure salinity in salt water and to use your hydrometer to compare density and salinity

2. Making the hydrometer-materials You will need a piece of graph paper to record your lab design and to record and graph your data for the comparison of density and salinity lab. The following may be used to design your hydrometer: Straws, coffee stirrer, clay (there are different types) tape (to create measurements), sharpie, ball bearings, rubber stopper

3. Making the hydrometer Look at the designs of the example hydrometers on the table, think about what might help them work well and what flaws they may have. Make sure that your design includes the following: 1. You must have a measuring scale on your hydrometer in mm. Use the tape and mark off each mm. Make your 5mm. marks longer (so 5mm, 10, 15, 20, etc will be more visible) 2. The 0 mm. will be at the top of your hydrometer (opposite end of the “bulb”) 3. Make sure your hydrometer floats upright. The higher your hydrometer floats the greater the density of the liquid

4. Making the hydrometer Testing your hydrometer Testing your hydrometer Use 500 ml of water. Place your hydrometer in the water and make sure it floats but that it is low in your water. Make sure it remains upright, so that you can easily measure. Make sure you have done the marks in waterproof ink. Use 500 ml of water. Place your hydrometer in the water and make sure it floats but that it is low in your water. Make sure it remains upright, so that you can easily measure. Make sure you have done the marks in waterproof ink.

5. Using your hydrometer: Comparing density and Salinity 1. Fill a 500 ml beaker with 300 ml of water. Place your hydrometer in the water. 2. Create a data table. In your data table, record what the water comes to on your mm scale

6. Using your hydrometer: Comparing density and Salinity Data Table Amount of Salt 0 grams 3 grams 6 grams 9 grams HydrometerReading

7. Using your hydrometer: Comparing density and Salinity 3. Remove the hydrometer and mix in 3 g of salt. Replace the hydormeter and record the water level 4. Repeat step 3 four more times, each time adding 3 more grams of salt to the water. Record the water level each time in the data table 5. Plot your data on a graph, making sure to label your x and y axis.

8. Using your hydrometer: Comparing density and Salinity Conclusion: Make sure to include the following in your conclusion: Why did you design the hydrometer the way you did? Did it float? Were you able to use it to measure density? Why did you design the hydrometer the way you did? Did it float? Were you able to use it to measure density? What did your data show you about salinity and density? What did your data show you about salinity and density? What general conclusion can you make about increasing salinity in water? What general conclusion can you make about increasing salinity in water?