Reef Chemistry Quiz 2007: A Preview!

[Randy Holmes-Farley]

Reef Chemistry Quiz 2007 is coming your way in just a few days.

It will post at Reefkeeping Magazine in the January issue.

For those who missed last years quiz, it is a fun way to test your reef chemistry knowledge, rank yourselves against others, and possibly learn something along the way.

The test consists of 50 multiple choice questions that range from medium to hard. You answer the questions, get a ranking, and can then see detailed explanations of the answers as well as a bar graph of everyone's scores. The rankings are:

90-100% Master Reef Chemist
80-89% Senior Reef Chemist
60-79% Reef Chemist
40-59% Apprentice Reef Chemist
26-39% Novice Reef Chemist
12-25% Neophyte Reef Chemist

To get you warmed up, here's a typical question that I had prepared as a backup question. I'll post a detailed answer tomorrow (Tuesday, 1/2/07).


Why can’t magnesium supplements be added to limewater (kalkwasser) before dosing to an aquarium?

A. Magnesium will precipitate as magnesium carbonate.
B. Calcium will precipitate as calcium hydroxide.
C. Magnesium will precipitate as magnesium sulfate.
D. Magnesium will precipitate as magnesium hydroxide.

[drummereef]

Awesome! I hate tests and anything to do with school for that matter, but this sounds like fun. :D

[SDguy]

D :D

And hey, now that I actually have used Lugol's, hope that question is still on there again :p

[Randy Holmes-Farley]

:lol:

Well, the second question has Lugol's as one of the multiple choices:

B. Molecular iodine (I2, such as is present in Lugol’s iodine solution)

:D

[MJAnderson]

I think I need to start studying! I read the question and knew the answer --- "it will cause precipitate" --- then read that choices were a little more specific... =)

[Randy Holmes-Farley]

Sometimes knowing half the answer is good enough. :D

[Craig Lambert]

If I remember correctly from the last test, if you reach the level of Apprentice Reef Chemist, you'll be scoring far better than most. Hopefully Randy grades on "the curve"............

[SDguy]

<a href=showthread.php?s=&postid=8871201#post8871201 target=_blank>Originally posted</a> by Randy Holmes-Farley
Sometimes knowing half the answer is good enough. :D

Not on a scantron it isn't :D

<a href=showthread.php?s=&postid=8871348#post8871348 target=_blank>Originally posted</a> by Craig Lambert
If I remember correctly from the last test, if you reach the level of Apprentice Reef Chemist, you'll be scoring far better than most. Hopefully Randy grades on "the curve"............

My PhD boss barely made it to Senior Reef Chemist last year, so don't feel bad...

[Paintbug]

im thinking C, but im probably wrong LOL

[DrBegalke]

D.

[chris.hampton]

A

[boxfishpooalot]

Yep D.

[Randy Holmes-Farley]

The correct answer is D: magnesium will precipitate as magnesium hydroxide. Limewater consists of a solution of calcium hydroxide in freshwater. Magnesium hydroxide is rather insoluble under the conditions present in limewater (high hydroxide concentration with a pH above 12) and magnesium hydroxide will precipitate from limewater. That precipitation will not only render the magnesium useless mud on the bottom of the container, but will reduce the alkalinity in the limewater, making it an unbalanced additive with excess calcium relative to the remaining alkalinity. More details on the solubility of magnesium in limewater are provided in this article:

http://www.advancedaquarist.com/issues/dec2003/chem.htm

[Randy Holmes-Farley]

Here's another:

Suppose that the water in a reef aquarium has a temperature of 80°F. If 10% of the water in the aquarium is replaced by artificial seawater of the same salinity at 60°F, the final temperature in the aquarium will be closest to which of the following values?

A. 78°F
B. 77°F
C. 76°F
D. Not enough information is provided to properly answer.

[DrBDC]

removed

[Craig Lambert]

78. (FWIW My edit was to delete a question about the previous post, not to change the answer)

[boxfishpooalot]

I think its d again because it depends how fast the water is added and the surrounding temp of the air.

Otherwise this question is really hard... :D

[Puffdragon]

My guess is A. 78

[dwculp]

<a href=showthread.php?s=&postid=8876842#post8876842 target=_blank>Originally posted</a> by Randy Holmes-Farley
Here's another:

Suppose that the water in a reef aquarium has a temperature of 80°F. If 10% of the water in the aquarium is replaced by artificial seawater of the same salinity at 60°F, the final temperature in the aquarium will be closest to which of the following values?

A. 78°F
B. 77°F
C. 76°F
D. Not enough information is provided to properly answer.

This would have been a great question for my 8th grade Integrated Physics and Chemistry class. Just before winter break I was teaching heat, equilibrium, specific heat etc....

One of the labs we do is mixing water of different temperatures together and then predicting and measuring the final temperature and measuring and calculating the heat loss and heat gained. Then we do it with alcohol, then water and alcohol.

[miracles38]

d. can't figure it out without volume of water.

[dwculp]

<a href=showthread.php?s=&postid=8878563#post8878563 target=_blank>Originally posted</a> by miracles38
d. can't figure it out without volume of water.

Yes you can, just think of it this way:

You have 9 parts 80 degree F water and 1 part 60 degree F water.

((9*80F) + (1*60F)) / 10 = 780F/10 = 78F!

[Tripspike]

Is a heater involved??? hehe

[boxfishpooalot]

would the speed at wich the water is added effect the final temperature though? I mean the prescise temp?

Other things like powerheads and lights would also need to take into account.

He did not say it was added instantly, or does that even matter?

[DrBDC]

Also, wouldn't you use the kelvin scale vs. F or C? And mass of rock retains temperature.

[Tripspike]

The glass dissipates heat faster also...oh so many factors..what aboutthe friction generated heat which is produced when you pour the 60 F water into the 80 water.

Trip

[dwculp]

You guys are reading too much into the question, classic mistake :)

[Tripspike]

It was stated that this took place in a reef aquarium, not in a couple of beakers.:crazy1:

[Randy Holmes-Farley]

Good thing this one isn't in the real quiz. :D

FWIW, I expected the answer to be 78, but the point about rocks etc may make answer D a good one too. That's why I have Team RC beta test the real quiz. :D

[Tripspike]

Randy, great job with this! Keep up the good work. I am looking forward to the quiz. It will be a great learning tool fo all of us.

Trip

[Randy Holmes-Farley]

Thanks. :)

[Watch Yo Wrasse]

Our body temperature is like 98 ... so like .. what about that?

[DrBDC]

So I guess if you are sitting in the tank during the water change it may counteract the temperature drop. :lol:

[SDguy]

<a href=showthread.php?s=&postid=8884883#post8884883 target=_blank>Originally posted</a> by Watch Yo Wrasse
Our body temperature is like 98 ... so like .. what about that?

So you probably shouldn't go swimming for too long in your tank... your acros might bleach :lol:

And please get out of the water if you have to pee :eek1:

[DrBDC]

unless it's a new tank and you're trying to kick start the cycle. :D

[ridetheducati]

<a href=showthread.php?s=&postid=8884883#post8884883 target=_blank>Originally posted</a> by Watch Yo Wrasse
Our body temperature is like 98 ... so like .. what about that?

You have to consider our body temps radiating out and effecting or is it affecting :) the 60 degree sample.

Great thread, one vote from me.

[DrBDC]

Depending on the mass of each vessel. The water change water will be effected more than the tank water. Then we need to get a thermography study done in order to see how much heat is radiated by the water changer. Is he mad, happy, depressed? What is thier normal body temp? There is a couple degree variation in people + or -.

[Victoria]

Right off the top of my head I'd say 78. Only because I've done it.

[chris.hampton]

And Randy said it earlier on!!! :beer:

[Victoria]

Thanks Chris for letting me know. I did not see that. But thanks again for pointing it out. I think I might of missed it if it was not for you. Really thanks soo sooo much.
Victoria

[chris.hampton]

Sorry i was only joking!!

[MJAnderson]

I think you're all ignoring the issue of measurement error, 78+/- 0.1 I think should be the extra credit answer.

We won't even discuss the observer effect. Just turning on the lights and standing near the tank will change the answer! =)

[Paintbug]

48% LOL good thing im did pay for a class on the subject. but i did improve over last years.

[six.line]

These quizzes are tough. I thought I had a fair handle on reef chemistry when I took that test. Randy sure put the kibosh on my ego. :D