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How Much Salt is How Much Salt is in in
Ocean Water?Ocean Water?
PurposePurpose
• To determine how many mL of salt To determine how many mL of salt there is in 200mL of ocean water.there is in 200mL of ocean water.
HypothesisHypothesis
• I think that there will be 6mL of salt I think that there will be 6mL of salt in the 200mL of ocean water. I tried a in the 200mL of ocean water. I tried a taste test before the mixtures went taste test before the mixtures went into the freezer.into the freezer.
MaterialsMaterials
• A sample of ocean waterA sample of ocean water• Small plastic cups/markerSmall plastic cups/marker• Measuring cupMeasuring cup• Table saltTable salt• ThermometerThermometer• FreezerFreezer• TeaspoonTeaspoon• Tap waterTap water• Syringe (to measure salt)Syringe (to measure salt)
ProcedureProcedure
1.1. Get a sample of ocean water, and a sample of tap water.Get a sample of ocean water, and a sample of tap water.2.2. Allow water to stand for 24 hours to achieve room Allow water to stand for 24 hours to achieve room
temperature.temperature.3.3. Number eight plastic cups and label the salt content as Number eight plastic cups and label the salt content as
0, 2, 4, 6, 8, 10, 12, and ocean water. 0, 2, 4, 6, 8, 10, 12, and ocean water. 4.4. Then measure out the amounts of salt and put the Then measure out the amounts of salt and put the
correct amount in each cup.correct amount in each cup.5.5. Pour 200mL of tap water into cups 1-7. Put 200mL of Pour 200mL of tap water into cups 1-7. Put 200mL of
ocean water in cup 8.ocean water in cup 8.6.6. Now, place the cups in a row in the same section of the Now, place the cups in a row in the same section of the
freezer, and make sure there aren’t other items around freezer, and make sure there aren’t other items around them.them.
7.7. Every 10 minutes, check the mixtures to see if there are Every 10 minutes, check the mixtures to see if there are any signs of freezing, and when there is, check the any signs of freezing, and when there is, check the mixtures every 5 minutes until the tops of the mixtures mixtures every 5 minutes until the tops of the mixtures are frozen.are frozen.
8.8. Repeat steps 4-7 two more times.Repeat steps 4-7 two more times.
VariablesVariables Manipulated Variable:Manipulated Variable: the amount of salt in each the amount of salt in each
cup.cup.
Responding Variable:Responding Variable: the time it takes for the the time it takes for the mixtures to freeze.mixtures to freeze.
Control Variables:Control Variables:1.1. The temperature of the freezer (-18 C)The temperature of the freezer (-18 C)2.2. Initial temperature of the mixtures (18 C)Initial temperature of the mixtures (18 C)3.3. The type of cups used in the experiment.The type of cups used in the experiment.4.4. Type of salt (table salt) Type of salt (table salt) 5.5. The placement of the cups in the freezer. (Placed in a The placement of the cups in the freezer. (Placed in a
row in the very back of the freezer)row in the very back of the freezer)6.6. Amount of water in each cup.Amount of water in each cup.
ObservationsObservations
The 12mL of salt mixture and the The 12mL of salt mixture and the ocean water look almost identical ocean water look almost identical when starting to freeze.when starting to freeze.
The cups with salt in them crystallize The cups with salt in them crystallize before they freeze.before they freeze.
After the mixtures crystallize, they After the mixtures crystallize, they turn slushy, and then slowly harden. turn slushy, and then slowly harden.
Results: Trial 1Results: Trial 1Cup #Cup # Amount Amount
Of Salt Of Salt 10 mins.10 mins. 20 mins. 20 mins. 30 mins.30 mins. 40 mins.40 mins. 45 mins.45 mins. 50 mins.50 mins.
#1#1 NoneNone NothingNothing Frost on Frost on the cupthe cup
Starting Starting to Freezeto Freeze
In process In process of freezingof freezing
FrozenFrozen --
#2#2 2mL2mL NothingNothing Frost on Frost on the cupthe cup
Starting Starting to Freezeto Freeze
In process In process of freezingof freezing
FrozenFrozen --
#3#3 4mL4mL NothingNothing Frost on Frost on the cupthe cup
Starting Starting to Freezeto Freeze
In process In process of freezingof freezing
FreezingFreezing In process In process of freezingof freezing
#4#4 6mL6mL NothingNothing Frost on Frost on the cupthe cup
NothingNothing NothingNothing Starting to Starting to FreezeFreeze
In process In process of freezingof freezing
#5#5 8mL8mL NothingNothing Frost on Frost on the cupthe cup
NothingNothing NothingNothing Starting to Starting to FreezeFreeze
Crystals Crystals and slushyand slushy
#6#6 10mL10mL NothingNothing Frost on Frost on the cupthe cup
NothingNothing Crystals Crystals and slushyand slushy
Crystals Crystals and slushyand slushy
Crystals Crystals and slushyand slushy
#7#7 12mL12mL NothingNothing Frost on Frost on the cupthe cup
NothingNothing NothingNothing NothingNothing NothingNothing
#8#8 Ocean Ocean WaterWater
NothingNothing Frost on Frost on the cupthe cup
NothingNothing NothingNothing NothingNothing Starting to Starting to FreezeFreeze
Results: Trial 1 Results: Trial 1 (continued)(continued)
Cup #Cup # Amount Amount of Saltof Salt
55 mins.55 mins. 60 mins.60 mins. 65 mins.65 mins. 70 mins.70 mins. 75 mins.75 mins. 80mins.80mins.
#1#1 NoneNone -- -- -- -- -- --
#2#2 2mL2mL -- -- -- -- -- --
#3#3 4mL4mL Close to Close to frozenfrozen
FrozenFrozen -- -- -- --
#4#4 6mL6mL Close to Close to frozenfrozen
Close to Close to frozen and frozen and
slushyslushy
Slush is Slush is hardeninghardening
Almost Almost frozenfrozen
FrozenFrozen --
#5#5 8mL8mL SlushySlushy SlushySlushy Slush is Slush is hardeninghardening
Close to Close to FrozenFrozen
Close to Close to FrozenFrozen
FrozenFrozen
#6#6 10mL10mL SlushySlushy SlushySlushy Slush is Slush is hardeninghardening
Close to Close to FrozenFrozen
Close to Close to FrozenFrozen
Close to Close to FrozenFrozen
#7#7 12mL12mL SlushySlushy SlushySlushy Slush is Slush is hardeninghardening
Close to Close to FrozenFrozen
SlushySlushy Close to Close to FrozenFrozen
#8#8 Ocean Ocean WaterWater
Crystals Crystals and slushand slush
slushyslushy Slush is Slush is hardeninghardening
Close to Close to FrozenFrozen
A little A little SlushySlushy
Close to Close to FrozenFrozen
Results: Trial 1 Results: Trial 1 (continued)(continued)
Cup #Cup # Amount Amount Of Salt Of Salt
85 85 mins.mins.
90 90 mins.mins.
#1#1 NoneNone -- --
#2#2 2mL2mL -- --
#3#3 4mL4mL -- --
#4#4 6mL6mL -- --
#5#5 8mL8mL -- --
#6#6 10mL10mL FrozenFrozen --
#7#7 12mL12mL Not quite Not quite FrozenFrozen
FrozenFrozen
#8#8 Ocean Ocean WaterWater
FrozenFrozen --
Results: Trial 2Results: Trial 2Cup #Cup # Amount Amount
Of Salt Of Salt 10 mins.10 mins. 20 mins. 20 mins. 30 mins.30 mins. 35 mins.35 mins. 40 mins.40 mins. 45 45
mins.mins.
#1#1 NoneNone NothingNothing NothingNothing NothingNothing Starting to Starting to FreezeFreeze
In process In process of freezingof freezing
FrozenFrozen
#2#2 2mL2mL NothingNothing NothingNothing Starting to Starting to FreezeFreeze
Starting to Starting to FreezeFreeze
FrozenFrozen --
#3#3 4mL4mL NothingNothing NothingNothing NothingNothing Starting to Starting to FreezeFreeze
Starting to Starting to FreezeFreeze
In In process process
of of FreezinFreezin
gg
#4#4 6mL6mL NothingNothing NothingNothing NothingNothing Starting to Starting to FreezeFreeze
Starting to Starting to FreezeFreeze
In In process process
of of FreezinFreezin
gg
#5#5 8mL8mL NothingNothing NothingNothing NothingNothing NothingNothing Starting to Starting to FreezeFreeze
In In process process
of of FreezinFreezin
gg
#6#6 10mL10mL NothingNothing NothingNothing NothingNothing Starting to Starting to FreezeFreeze
NothingNothing In In process process
of of FreezinFreezin
gg
#7#7 12mL12mL NothingNothing NothingNothing NothingNothing NothingNothing NothingNothing NothingNothing
#8#8 Ocean Ocean WaterWater
NothingNothing NothingNothing NothingNothing Starting to Starting to FreezeFreeze
Starting to Starting to FreezeFreeze
In In process process
of of FreezinFreezin
gg
Results: Trial 2 Results: Trial 2 (continued)(continued)
Cup Cup ##
Amount Amount of Saltof Salt
55 55 mins.mins.
60 60 mins.mins.
65 65 mins.mins.
70 70 mins.mins.
75 75 mins.mins.
80mins.80mins.
#1#1 NoneNone -- -- -- -- -- --
#2#2 2mL2mL -- -- -- -- -- --
#3#3 4mL4mL In In process process
of of FreezingFreezing
FrozenFrozen -- -- -- --
#4#4 6mL6mL In In process process
of of FreezingFreezing
SlushySlushy SlushySlushy FrozenFrozen -- --
#5#5 8mL8mL In In process process
of of FreezingFreezing
SlushySlushy SlushySlushy SlushySlushy FrozenFrozen --
#6#6 10mL10mL In In process process
of of FreezingFreezing
SlushySlushy SlushySlushy SlushySlushy SlushySlushy SlushySlushy
#7#7 12mL12mL NothingNothing SlushySlushy SlushySlushy SlushySlushy SlushySlushy SlushySlushy
#8#8 Ocean Ocean WaterWater
SlushySlushy SlushySlushy SlushySlushy SlushySlushy HardeniHardening slushng slush
SlushySlushy
Results: Trial 2 (continued)Results: Trial 2 (continued)
Cup #Cup # Amount Amount Of Salt Of Salt
85 mins.85 mins. 90 mins.90 mins. 95 mins.95 mins. 100 100 mins.mins.
#1#1 NoneNone -- -- -- --
#2#2 2mL2mL -- -- -- --
#3#3 4mL4mL -- -- -- --
#4#4 6mL6mL -- -- -- --
#5#5 8mL8mL -- -- -- --
#6#6 10mL10mL FrozenFrozen -- -- --
#7#7 12mL12mL SlushySlushy SlushySlushy SlushySlushy FrozenFrozen
#8#8 Ocean Ocean WaterWater
FrozenFrozen -- -- --
Results: Trial 3Results: Trial 3Cup #Cup # Amount Amount
of Saltof Salt10 10
mins.mins.20 20
mins.mins.30 mins. 30 mins. 35 35
mins.mins.40 mins.40 mins. 45 45
mins.mins.
#1#1 NoneNone NothingNothing Frost on Frost on CupCup
NothingNothing Starting Starting to Freezeto Freeze
Starting Starting to Freezeto Freeze
In In process process
of of FreezingFreezing
#2#2 2mL2mL NothingNothing Frost on Frost on CupCup
NothingNothing Starting Starting to Freezeto Freeze
Starting Starting to Freezeto Freeze
In In process process of of FreezingFreezing
#3#3 4mL4mL NothingNothing Frost on Frost on CupCup
Starting Starting to Freezeto Freeze
Starting Starting to Freezeto Freeze
Starting Starting to Freezeto Freeze
In In process process of of FreezingFreezing
#4#4 6mL6mL NothingNothing Frost on Frost on CupCup
NothingNothing NothingNothing Starting Starting to Freezeto Freeze
Starting Starting to Freezeto Freeze
#5#5 8mL8mL NothingNothing Frost on Frost on CupCup
NothingNothing NothingNothing NothingNothing NothingNothing
#6#6 10mL10mL NothingNothing Frost on Frost on CupCup
NothingNothing Starting Starting to Freezeto Freeze
Starting Starting to Freezeto Freeze
In In process process
of of FreezingFreezing
#7#7 12mL12mL NothingNothing Frost on Frost on CupCup
NothingNothing NothingNothing NothingNothing NothingNothing
#8#8 Ocean Ocean WaterWater
NothingNothing Frost on Frost on CupCup
NothingNothing NothingNothing NothingNothing NothingNothing
Results: Trial 3 Results: Trial 3 (continued)(continued)
Cup #Cup # Amount Amount of Saltof Salt
50 mins.50 mins. 55 mins.55 mins. 60 mins. 60 mins. 65 mins.65 mins. 70 mins.70 mins. 75 mins.75 mins.
#1#1 NoneNone In process In process of of
FreezingFreezing
NothingNothing FrozenFrozen -- -- --
#2#2 2mL2mL In process In process of of
FreezingFreezing
FrozenFrozen -- -- -- --
#3#3 4mL4mL In process In process of of
FreezingFreezing
FrozenFrozen -- -- -- --
#4#4 6mL6mL In process In process of of
FreezingFreezing
NothingNothing SlushySlushy NothingNothing SlushySlushy FrozenFrozen
#5#5 8mL8mL In process In process of of
FreezingFreezing
NothingNothing SlushySlushy NothingNothing SlushySlushy FrozenFrozen
#6#6 10mL10mL In process In process of of
FreezingFreezing
NothingNothing SlushySlushy NothingNothing SlushySlushy SlushySlushy
#7#7 12mL12mL NothingNothing NothingNothing SlushySlushy NothingNothing SlushySlushy SlushySlushy
#8#8 Ocean Ocean WaterWater
In process In process of of
FreezingFreezing
NothingNothing SlushySlushy NothingNothing SlushySlushy SlushySlushy
Results: Trial 3 Results: Trial 3 (continued)(continued)
Cup #Cup # 80 mins.80 mins. 85 mins.85 mins. 90 mins.90 mins.
#1#1 -- -- --
#2#2 -- -- --
#3#3 -- -- --
#4#4 -- -- --
#5#5 -- -- --
#6#6 FrozenFrozen -- --
#7#7 SlushySlushy Slush is Starting Slush is Starting to hardento harden
FrozenFrozen
#8#8 SlushySlushy Slush is starting Slush is starting to hardento harden
FrozenFrozen
Time for Samples to Time for Samples to FreezeFreeze
Trial Trial ##
#1-#1-NoneNone
#2-#2-2mL2mL
#3-#3-4mL4mL
#4-#4-6mL6mL
#5-#5-8mL8mL
#6-#6-10mL10mL
#7-#7-12mL12mL
#8-#8-Ocean Ocean WaterWater
# 1# 1 45 45 mins.mins.
45 45 mins.mins.
60 60 mins.mins.
75 75 mins.mins.
80 80 mins.mins.
85 85 mins.mins.
90 90 mins.mins.
85 85 mins.mins.
# 2# 2 45 45 mins.mins.
40 40 mins.mins.
60 60 mins.mins.
70 70 mins.mins.
75 75 mins.mins.
85 85 mins. mins.
100 100 mins.mins.
85 85 mins.mins.
# 3# 3 60 60 mins.mins.
55 55 mins.mins.
55 55 mins.mins.
75 75 mins.mins.
75 75 mins.mins.
80 80 mins.mins.
90 90 mins.mins.
90 90 mins.mins.
AnalysisAnalysisRate at which the Salt Water Mixtures
Froze
0
20
40
60
80
100
0 2 4 6 8 10 12 ow
Amount of Salt (mL)
Tim
e (
min
ute
s)
Trial 1Trial 2Trial 3
ConclusionConclusion
After gathering my information, it seems After gathering my information, it seems that in 200mL of ocean water, there is that in 200mL of ocean water, there is about 10-12mL of salt. My hypothesis was about 10-12mL of salt. My hypothesis was wrong. While I was doing my trials, I noticed wrong. While I was doing my trials, I noticed that the ocean water mostly froze at the that the ocean water mostly froze at the same time as the 10mL or the 12mL salt same time as the 10mL or the 12mL salt mixture. Therefore, I conclude that there is mixture. Therefore, I conclude that there is between 10 and 12mL of salt in 200mL of between 10 and 12mL of salt in 200mL of ocean water. To be more accurate I would ocean water. To be more accurate I would have to conduct more trials using 1mL have to conduct more trials using 1mL increments of salt.increments of salt.
Sources of ErrorSources of Error Where I placed the cups in the freezer was a big factor on Where I placed the cups in the freezer was a big factor on
how the mixtures froze, because it was colder in the back how the mixtures froze, because it was colder in the back of the freezer rather than the front (I learned this the hard of the freezer rather than the front (I learned this the hard way and had to redo the whole trial)way and had to redo the whole trial)
It was tricky to measure the salt and the water, so it It was tricky to measure the salt and the water, so it might not be exactly right.might not be exactly right.
How warm or cold the mixtures are. (I left the mixtures on How warm or cold the mixtures are. (I left the mixtures on the counter for 24 hours before doing my experiments)the counter for 24 hours before doing my experiments)
Any chemicals in the tap water could have affected the Any chemicals in the tap water could have affected the results in freezing.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 If the salt was not completely dissolved and stirred
throughout, there may have been surface freezing of throughout, there may have been surface freezing of plain water.plain water.
Amount of time the freezer door was open while I Amount of time the freezer door was open while I collected my data.collected my data.
Ways to ImproveWays to Improve
1.1. Try the experiment again, except Try the experiment again, except this time instead of going up in this time instead of going up in increments of 2mL, for the amounts increments of 2mL, for the amounts of salt, go up by 1mL each time.of salt, go up by 1mL each time.
2.2. Try boiling amounts of ocean water Try boiling amounts of ocean water and collecting the residue of salt. and collecting the residue of salt. Measure the amount of salt Measure the amount of salt remaining.remaining.
3.3. Try using rock salt instead of table Try using rock salt instead of table salt. salt.