How Much Salt is in Ocean Water?

Purpose To determine how many mL of salt there is in 200mL of ocean water. To determine how many mL of salt there is in 200mL of ocean water.

Hypothesis I think that there will be 6mL of salt in the 200mL of ocean water. I tried a taste test before the mixtures went into the freezer. I think that there will be 6mL of salt in the 200mL of ocean water. I tried a taste test before the mixtures went into the freezer.

Materials A sample of ocean water A sample of ocean water Small plastic cups/marker Small plastic cups/marker Measuring cup Measuring cup Table salt Table salt Thermometer Thermometer Freezer Freezer Teaspoon Teaspoon Tap water Tap water Syringe (to measure salt) Syringe (to measure salt)

Procedure 1. Get a sample of ocean water, and a sample of tap water. 2. Allow water to stand for 24 hours to achieve room temperature. 3. Number eight plastic cups and label the salt content as 0, 2, 4, 6, 8, 10, 12, and ocean water. 4. Then measure out the amounts of salt and put the correct amount in each cup. 5. Pour 200mL of tap water into cups 1-7. Put 200mL of ocean water in cup Now, place the cups in a row in the same section of the freezer, and make sure there aren’t other items around them. 7. Every 10 minutes, check the mixtures to see if there are any signs of freezing, and when there is, check the mixtures every 5 minutes until the tops of the mixtures are frozen. 8. Repeat steps 4-7 two more times.

Variables Manipulated Variable: the amount of salt in each cup. Manipulated Variable: the amount of salt in each cup. Responding Variable: the time it takes for the mixtures to freeze. Responding Variable: the time it takes for the mixtures to freeze. Control Variables: Control Variables: 1. The temperature of the freezer (-18 C) 2. Initial temperature of the mixtures (18 C) 3. The type of cups used in the experiment. 4. Type of salt (table salt) 5. The placement of the cups in the freezer. (Placed in a row in the very back of the freezer) 6. Amount of water in each cup.

Observations The 12mL of salt mixture and the ocean water look almost identical when starting to freeze. The 12mL of salt mixture and the ocean water look almost identical when starting to freeze. The cups with salt in them crystallize before they freeze. The cups with salt in them crystallize before they freeze. After the mixtures crystallize, they turn slushy, and then slowly harden. After the mixtures crystallize, they turn slushy, and then slowly harden.

Results: Trial 1 Cup # Amount Of Salt 10 mins. 20 mins. 30 mins. 40 mins. 45 mins. 50 mins. #1NoneNothing Frost on the cup Starting to Freeze In process of freezing Frozen- #22mLNothing Frost on the cup Starting to Freeze In process of freezing Frozen- #34mLNothing Frost on the cup Starting to Freeze In process of freezing Freezing #46mLNothing Frost on the cup NothingNothing Starting to Freeze In process of freezing #58mLNothing Frost on the cup NothingNothing Starting to Freeze Crystals and slushy #610mLNothing Frost on the cup Nothing Crystals and slushy #712mLNothing Frost on the cup NothingNothingNothingNothing #8 Ocean Water Nothing Frost on the cup NothingNothingNothing Starting to Freeze

Results: Trial 1 (continued) Cup # Amount of Salt 55 mins. 60 mins. 65 mins. 70 mins. 75 mins. 80mins. #1None #22mL #34mL Close to frozen Frozen---- #46mL Close to frozen and slushy Slush is hardening Almost frozen Frozen- #58mLSlushySlushy Slush is hardening Close to Frozen Frozen #610mLSlushySlushy Slush is hardening Close to Frozen #712mLSlushySlushy Slush is hardening Close to Frozen Slushy #8 Ocean Water Crystals and slush slushy Slush is hardening Close to Frozen A little Slushy Close to Frozen

Results: Trial 1 (continued) Cup # Amount Of Salt 85 mins. 90 mins. #1None-- #22mL-- #34mL-- #46mL-- #58mL-- #610mLFrozen- #712mL Not quite Frozen Frozen #8 Ocean Water Frozen-

Results: Trial 2 Cup # Amount Of Salt 10 mins. 20 mins. 30 mins. 35 mins. 40 mins. 45 mins. #1NoneNothingNothingNothing Starting to Freeze In process of freezing Frozen #22mLNothingNothing Starting to Freeze Frozen- #34mLNothingNothingNothing In process of Freezing #46mLNothingNothingNothing Starting to Freeze In process of Freezing #58mLNothingNothingNothingNothing Starting to Freeze In process of Freezing #610mLNothingNothingNothing Starting to Freeze Nothing In process of Freezing #712mLNothingNothingNothingNothingNothingNothing #8 Ocean Water NothingNothingNothing Starting to Freeze In process of Freezing

Results: Trial 2 (continued) Cup # Amount of Salt 55 mins. 60 mins. 65 mins. 70 mins. 75 mins. 80mins. #1None #22mL #34mL In process of Freezing Frozen---- #46mL SlushySlushyFrozen-- #58mL SlushySlushySlushyFrozen- #610mL SlushySlushySlushySlushySlushy #712mLNothingSlushySlushySlushySlushySlushy #8 Ocean Water SlushySlushySlushySlushy Hardenin g slush Slushy

Results: Trial 2 (continued) Cup # Amount Of Salt 85 mins. 90 mins. 95 mins. 100 mins. #1None---- #22mL---- #34mL---- #46mL---- #58mL---- #610mLFrozen--- #712mLSlushySlushySlushyFrozen #8 Ocean Water Frozen---

Results: Trial 3 Cup # Amount of Salt 10 mins. 20 mins. 30 mins. 35 mins. 40 mins. 45 mins. #1NoneNothing Frost on Cup Nothing Starting to Freeze In process of Freezing #22mLNothing Frost on Cup Nothing Starting to Freeze In process of Freezing #34mLNothing Frost on Cup Starting to Freeze In process of Freezing #46mLNothing Frost on Cup NothingNothing Starting to Freeze #58mLNothing Frost on Cup NothingNothingNothingNothing #610mLNothing Nothing Starting to Freeze In process of Freezing #712mLNothing Frost on Cup NothingNothingNothingNothing #8 Ocean Water Nothing Frost on Cup NothingNothingNothingNothing

Results: Trial 3 (continued) Cup # Amount of Salt 50 mins. 55 mins. 60 mins. 65 mins. 70 mins. 75 mins. #1None In process of Freezing NothingFrozen--- #22mL Frozen---- #34mL Frozen---- #46mL NothingSlushyNothingSlushyFrozen #58mL NothingSlushyNothingSlushyFrozen #610mL NothingSlushyNothingSlushySlushy #712mLNothingNothingSlushyNothingSlushySlushy #8 Ocean Water In process of Freezing NothingSlushyNothingSlushySlushy

Results: Trial 3 (continued) Cup # 80 mins. 85 mins. 90 mins. #1--- #2--- #3--- #4--- #5--- #6Frozen-- #7Slushy Slush is Starting to harden Frozen #8Slushy Slush is starting to harden Frozen

Time for Samples to Freeze Trial # #1- None #2- 2mL #3- 4mL #4- 6mL #5- 8mL #6- 10mL #7- 12mL #8- Ocean Water # 1 45 mins. 60 mins. 75 mins. 80 mins. 85 mins. 90 mins. 85 mins. # 2 45 mins. 40 mins. 60 mins. 70 mins. 75 mins. 85 mins. 100 mins. 85 mins. # 3 60 mins. 55 mins. 75 mins. 80 mins. 90 mins.

Analysis

Conclusion After gathering my information, it seems that in 200mL of ocean water, there is about mL of salt. My hypothesis was wrong. While I was doing my trials, I noticed that the ocean water mostly froze at the same time as the 10mL or the 12mL salt mixture. Therefore, I conclude that there is between 10 and 12mL of salt in 200mL of ocean water. To be more accurate I would have to conduct more trials using 1mL increments of salt.

Sources of Error Where I placed the cups in the freezer was a big factor on how the mixtures froze, because it was colder in the back of the freezer rather than the front (I learned this the hard way and had to redo the whole trial) Where I placed the cups in the freezer was a big factor on how the mixtures froze, because it was colder in the back of the freezer rather than the front (I learned this the hard way and had to redo the whole trial) It was tricky to measure the salt and the water, so it might not be exactly right. It was tricky to measure the salt and the water, so it might not be exactly right. How warm or cold the mixtures are. (I left the mixtures on the counter for 24 hours before doing my experiments) How warm or cold the mixtures are. (I left the mixtures on the counter for 24 hours before doing my experiments) Any chemicals in the tap water could have affected the results in freezing. Any chemicals in the tap water could have affected the results in freezing. The temperature of the freezer each time I used it. The temperature of the freezer each time I used it. If the salt was not completely dissolved and stirred throughout, there may have been surface freezing of plain water. If the salt was not completely dissolved and stirred throughout, there may have been surface freezing of plain water. Amount of time the freezer door was open while I collected my data. Amount of time the freezer door was open while I collected my data.

Ways to Improve 1. Try the experiment again, except this time instead of going up in increments of 2mL, for the amounts of salt, go up by 1mL each time. 2. Try boiling amounts of ocean water and collecting the residue of salt. Measure the amount of salt remaining. 3. Try using rock salt instead of table salt.