Water Quality B/C

emescferrall
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Re: Water Quality B/C

Postby emescferrall » January 8th, 2014, 8:37 am

My coach told me this morning that I will be competing Water Quality for the first time on Saturday. My partner has done it before, but she didn't have any notes. Please help!!! Has the Wiki been updated yet???
I took first at 2013 States as a 6th grader in Meteorology!!!

2014 State Results:

Anatomy: 2nd
Can't Judge A Powder: 9th
Crime Busters: 1st
Heredity: 3rd
Meteorology: 3rd
Sounds of Music: 2nd

2015 Events: Anatomy, Crave The Wave, Crime Busters, Experimental Design, Meteorology, Picture This

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caseyotis
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Re: Water Quality B/C

Postby caseyotis » January 8th, 2014, 5:57 pm

My coach told me this morning that I will be competing Water Quality for the first time on Saturday. My partner has done it before, but she didn't have any notes. Please help!!! Has the Wiki been updated yet???
The wiki hasn't been updated... The best thing for you to do is look at the Training Handout and PowerPoint, which can be found at soinc.org. There are a lot of useful notes there.
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emescferrall
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Re: Water Quality B/C

Postby emescferrall » January 8th, 2014, 7:33 pm

Thank you!!
I took first at 2013 States as a 6th grader in Meteorology!!!

2014 State Results:

Anatomy: 2nd
Can't Judge A Powder: 9th
Crime Busters: 1st
Heredity: 3rd
Meteorology: 3rd
Sounds of Music: 2nd

2015 Events: Anatomy, Crave The Wave, Crime Busters, Experimental Design, Meteorology, Picture This

colorado mtn science
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Re: Water Quality B/C

Postby colorado mtn science » January 9th, 2014, 9:27 am

I noticed that I was making a mistake calibrating my salinometer, and I'm thinking this might be a common mistake. When mixing saline solutions I would mess up my total. For example, if I wanted 4% salinity, I would mix 400 g of distilled water with 16 g of salt, because 16 is 4% of 400. However, my total solute to solution ratio would be 16 g of salt over 416 total grams of saltwater solution, and 16 is not 4% of 416. Basically, my results were thrown off because I didn't take into account the total amount of solution. What I should have done to get 400 g of 4% salt water was to mix 16 grams of salt with 384 grams of water. Has anyone else made this mistake?

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rtunnel97
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Re: Water Quality B/C

Postby rtunnel97 » January 9th, 2014, 3:58 pm

colorado mtn science, my partner and i, when we first started water quality two years ago, luckily had a chemistry teacher show us this common error but i could see how this could happen though, hopefully everyone is having a grand ol time calibrating those salinometers right now hahahaha :D
Last edited by rtunnel97 on January 9th, 2014, 6:18 pm, edited 2 times in total.
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ptkid
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Re: Water Quality B/C

Postby ptkid » January 9th, 2014, 6:06 pm

I noticed that I was making a mistake calibrating my salinometer, and I'm thinking this might be a common mistake. When mixing saline solutions I would mess up my total. For example, if I wanted 4% salinity, I would mix 400 g of distilled water with 16 g of salt, because 16 is 4% of 400. However, my total solute to solution ratio would be 16 g of salt over 416 total grams of saltwater solution, and 16 is not 4% of 416. Basically, my results were thrown off because I didn't take into account the total amount of solution. What I should have done to get 400 g of 4% salt water was to mix 16 grams of salt with 384 grams of water. Has anyone else made this mistake?
wait, back in the first year of WQ there was a rules clarification on how to make the saline solution for salinometer testing.

It said "Note: At Nationals, the saltwater solution (most likely NaCl) will be made by adding salt to a volume of water until a predetermined total volume is reached (e.g., a 6.5% solution can be made by dissolving 65g of NaCl in water until a total volume of 1L is reached. Teams will record concentrations in percent (1-10 and estimate the tenth). At Nationals (maybe State) any percent ± 0.5 (maybe ± 1 at Invitationals/Regional) will be given full credit (partial credit may be awarded for other percents). The points for this testing should be approximately 5% of the total score (e.g., if a team recorded between 6.0-7.0%, they could receive 5 points out of 100). There is no restriction on the salinometer type as long as the team builds it."

So if I understand this correctly you would (to make a 6.5% solution):
1. get a graduated cylinder for 1L and dump 65g of NaCl into it.
2. fill the graduated cylinder with water until the meniscus of the water reaches 1L.
3. Then mix.

This would have a greater mass than the way you described above about by creating the solution by mass right? These 2 ways are definitely not the same.
So which way is correct?

EDIT: If by mass, I have calibrated my salinometer wrong for every competition.
Seven Lakes High School '16
Previous National Champion in Green Generation and National Medalist in CJAP, Disease Detectives, Entomology, & Water Quality

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rtunnel97
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Re: Water Quality B/C

Postby rtunnel97 » January 9th, 2014, 6:17 pm

i have never done it by mass. just filled to the 100mL mark on the graduated cylinder.
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Smithy0013
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Re: Water Quality B/C

Postby Smithy0013 » January 9th, 2014, 8:43 pm

Anyone else find it a little ridiculous that they can throw literally any salt they want at us? like not just NaCl. There are so many salts its insane. Can you imagine going into a competion and hearing "alright tell us what percent potassium dichromate is in the water" I know I'd be drooling. So anyway... Does anyone actually compensate for this? If so... how? Chem was kinda my weak science so I'm lost aside from testing every salt in my chem teachers back room.

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caseyotis
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Re: Water Quality B/C

Postby caseyotis » January 10th, 2014, 3:29 am

It says most likely NaCl, and to be honest, I don't know why they'd do any other type of salt...
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Welcome, welcome
“Goodbye,” said the fox.
“And now here is my secret, a very simple secret:
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what is essential is invisible to the
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rtunnel97
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Re: Water Quality B/C

Postby rtunnel97 » January 11th, 2014, 5:23 am

every competition ive been to, they have used NaCl, i have always calibrated my device with NaCl
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