Brain Candy

[ChemEngineer]

GoodKidsFun

GoodKidsFun.blogspot.com

 

[Jim H - VA USA]

I was taught ( engineering major) that both ice and water are usually present at 0 degrees C (one atmosphere of pressure). It is very difficult to maintain only ice at 0 degrees C or only water at 0 degrees C.

Big Joe, in an unusual combination of mechanical and chemical engineering, I just replaced my refrigerator water filter after 6 1/2 years of constant use. (Manufacturers recommend changing it every six months, so I was only off by just over one order of magnitude, but who's counting.)

I cut both ends off with a hacksaw, resulting in fine white plastic particles, not contaminants from the filter. Then I sliced the carbon filter with a razor blade and there was absolutely nothing visible that the filter captured.

Obviously water filters don't do much but they're pretty expensive. The new one was $25.
Tap water won't kill ya. Gramma and grampa grew up on it.

View attachment 452976

The activated carbon may have adsorbed some trace chemicals and lost their adsorptive capacity. We survived, somehow.

That is so funny. I also cut my refrigerator water filter open. I did mine after three years. It still had plenty of life left.

I will not replace it again until it is clogged enough to restrict flow.

The six months' guidance might be appropriate for someone on a well with pretty bad water, but as you are well aware, they recommend six months to cover the worst-case scenario and maximize revenue.

My filters are ridiculously expensive for basically being a little activated carbon and paper towels.

Many refrigerators will work just fine without a water filter installed. Mine will. So that's another option for people who have perfectly-drinkable water from their tap, like me.

 

[ChemEngineer]

What is so obviously true of refrigerator water filters is likewise true of automotive oil filters. I hacksawed mine open after 5,000 miles and although the dirty oil blackened the paper, the amount of solids filtered by the paper was miniscule. I'd say you can replace your auto oil filters once ever 20,000 to 40,000 miles and save quite a bit, provided that you empty the dirty oil out of the filter and then replace it.

 

[Jim H - VA USA]

If you add a liter of water at the boiling point, 100 degrees Celsius, to a liter of water at its freezing point, 0 degrees Celsius, you obviously get two liters at 50 degrees C.

1) Without doing any calculations what is your best guess of what the equilibrium temperature is when you add a liter of water at 100 C to a liter frozen into ice at 0 C?

2) Now what is your best guess of what the equilibrium temperature is when you add three liters frozen into ice at 0 C to a kilogram (liter of water) of steam at 100 C in a perfectly insulated container?

The answers are amazing.

No calcs?! Okay, that's tough. I won't calc in my head; I will guesstimate...

Heat of fusion 330 J/g
Heat of vaporization 2250 J/g
Heat capacity 4200 J/gK

Not doing any calcs at all, I will guess
1) 40C
2) I find this one quite challenging to guestimate, since there is a mass difference...
The steam condensation still takes more energy than melting the larger amount of ice, so I will guess 60C.

Now I will go read the subsequent posts and find out how wrong I am.

I would prefer to do the calcs, since they are quite simple.

 

[Jim H - VA USA]

What is so obviously true of refrigerator water filters is likewise true of automotive oil filters. I hacksawed mine open after 5,000 miles and although the dirty oil blackened the paper, the amount of solids filtered by the paper was miniscule. I'd say you can replace your auto oil filters once ever 20,000 to 40,000 miles and save quite a bit, provided that you empty the dirty oil out of the filter and then replace it.

The problem will be removing them after driving that long. I know people who have done it and heard about it on Car Talk as well. The gasket will absolutely attach to the gasket mounting surface, and most oil filter wrenches will not be able to remove it.

I suppose one might be able to "crack the seal" on the oil filter by loosening it, and then tightening it every 5000 or so miles and reuse it for an extended period. (Not recommending this. It is a guess.)

Since my oil filters are less than 10 bucks, and they are protecting a $4000 engine, I don't skimp on them.

Engine oil prices are outrageous these days. $5 per quart. Wow. Antifreeze is also crazy expensive.

 

[Jim H - VA USA]

If you add a liter of water at the boiling point, 100 degrees Celsius, to a liter of water at its freezing point, 0 degrees Celsius, you obviously get two liters at 50 degrees C.

1) Without doing any calculations what is your best guess of what the equilibrium temperature is when you add a liter of water at 100 C to a liter frozen into ice at 0 C?

2) Now what is your best guess of what the equilibrium temperature is when you add three liters frozen into ice at 0 C to a kilogram (liter of water) of steam at 100 C in a perfectly insulated container?

The answers are amazing.

No calcs?! Okay, that's tough. I won't calc in my head; I will guesstimate...

Heat of fusion 330 J/g
Heat of vaporization 2250 J/g
Heat capacity 4200 J/gK

Not doing any calcs at all, I will guess
1) 40C
2) I find this one quite challenging to guestimate, since there is a mass difference...
The steam condensation still takes more energy than melting the larger amount of ice, so I will guess 60C.

Now I will go read the subsequent posts and find out how wrong I am.

I would prefer to do the calcs, since they are quite simple.

Now calcs, but just estimates...

1)
Melting ice: 330 kJ
330 kJ / 4.2 kJ/gK / 2000g = 0.04C
50C - 0.04C = 50C (slightly less than 50C, but not significant)

Wow, that is amazing.

Of course, if getting a precise answer was important, I would use m c delta-T and all that properly.

2)
Melting ice: 990kJ
Condensing steam: 2250 kJ
Delta (net energy) = 1260 kJ

1260 kJ / 4000g / 4.2 kJ/gK = 0.075K
Estimate of equilibrium temp w/o phase changes: 3*0 + 100 = 25C
25C + 0.075K = 25.1C

That is amazing as well.

If I messed up by a factor of 1000 somewhere, I would not be surprised.

 

[Jim H - VA USA]

My answer was...

View attachment 452930

If I am drinking it, it is half empty.

If I am pouring it, it is half full.

Of course, ChemEngineer would tell us that the glass is always full, since air will always ensure that.

 

[ChemEngineer]

Sam consistently caught more fish than any other fisherman on the lake. Whereas the other guys would catch two or three fish a day, Sam consistently brought in a large stringer full of trout.

Curious as to Sam's success, the local warden asked his secret. Sam invited him to go fishing the next day. When they got to the middle of the lake, Sam stopped the boat, pulled out a stick of dynamite, lit it, and threw it into the air as far as he could. The explosion rocked the lake and dead fish began floating to the top. The game warden went crazy. "You can't do that. I'm gonna fine you and lock you up, Sam!"

Sam responded by lighting a stick of dynamite and throwing it in the game warden's lap. "Are you gonna just sit there complaining or are you gonna fish?"

 

[ChemEngineer]

If you add a liter of water at the boiling point, 100 degrees Celsius, to a liter of water at its freezing point, 0 degrees Celsius, you obviously get two liters at 50 degrees C.

1) Without doing any calculations what is your best guess of what the equilibrium temperature is when you add a liter of water at 100 C to a liter frozen into ice at 0 C?

2) Now what is your best guess of what the equilibrium temperature is when you add three liters frozen into ice at 0 C to a kilogram (liter of water) of steam at 100 C in a perfectly insulated container?

The answers are amazing.

No calcs?! Okay, that's tough. I won't calc in my head; I will guesstimate...

Heat of fusion 330 J/g
Heat of vaporization 2250 J/g
Heat capacity 4200 J/gK

Not doing any calcs at all, I will guess
1) 40C
2) I find this one quite challenging to guestimate, since there is a mass difference...
The steam condensation still takes more energy than melting the larger amount of ice, so I will guess 60C.

Now I will go read the subsequent posts and find out how wrong I am.

I would prefer to do the calcs, since they are quite simple.

Now calcs, but just estimates...

1)
Melting ice: 330 kJ
330 kJ / 4.2 kJ/gK / 2000g = 0.04C
50C - 0.04C = 50C (slightly less than 50C, but not significant)

Wow, that is amazing.

Of course, if getting a precise answer was important, I would use m c delta-T and all that properly.

2)
Melting ice: 990kJ
Condensing steam: 2250 kJ
Delta (net energy) = 1260 kJ

1260 kJ / 4000g / 4.2 kJ/gK = 0.075K
Estimate of equilibrium temp w/o phase changes: 3*0 + 100 = 25C
25C + 0.075K = 25.1C

That is amazing as well.

If I messed up by a factor of 1000 somewhere, I would not be surprised.

More simply, just look at one gram of water, ice, and steam.

Delta phase change for steam in cooling to water at the same temperature, 100 C, yields 540 calories.
Delta phase change for ice at 0 C absorbs the first 80 calories. Multiply that by three and it's 240 calories. Then three grams of water at 0 C absorbs the remaining 300 calories in one gram of steam so all end up at 100 C.

Imagine waving a magic wand over a teaspoon of water, call it a gram equivalent weight. (Close enough.) Your magic wand increases the size of ever water molecule to a quarter of an inch diameter. How much volume would that water now occupy? (Go big. Way big.)

It would raise the ocean level by about 1200 feet. That's how small molecules are.

 

[ChemEngineer]

 

[Flash]

If you add a liter of water at the boiling point, 100 degrees Celsius, to a liter of water at its freezing point, 0 degrees Celsius, you obviously get two liters at 50 degrees C.

Without doing any calculations what is your best guess of what the equilibrium temperature is when you add a liter of water at 100 C to a liter frozen into ice at 0 C?

Now what is your best guess of what the equilibrium temperature is when you add three liters frozen into ice at 0 C to a kilogram (liter of water) of steam at 100 C in a perfectly insulated container?

The answers are amazing.

If I remember correctly there was a question like this on my PE examination.

I probably got it wrong. It took me three times to get the PE certification.

 

[ChemEngineer]

 

[ChemEngineer]

 

[ChemEngineer]

 

[ChemEngineer]

Quite a few countries named their capital city after the country. My favorite starts with a D.
Can you guess what it is? I don't think so.

Andorra

Djibouti

Guatemala

Kuwait

Luxemburg

Kuwait

Mexico

San Marino

Sao Tome

 

[ChemEngineer]

 

[borninnj]

Seventy-two views and only one guess by JoMoma.

Don't be afraid to guess wrong, people.



A gram of ice melts while absorbing 80 calories which cools the hot water from 100 to 20 C.

Equal quantities of 20 C water and 0 C water equilibrate at 10 degrees C. (Heat of fusion = 80 cal/gram)


Now add one pound, ton, or gram of ice at 0 degrees Celsius while piping in a like amount of steam at 100 degrees C and what do you think the equilibrium temperature will be? (It’s crazy.)


The first gram of steam entirely melts all the equal amount of ice while losing only 80 calories. It then loses another 100 calories raising the temperature from 0 to 100. All the water and steam are 100 degrees C. Another two grams of ice can be added and the final equilibrium temperature of 3 grams, or pounds, or tons of ice with 1 gram, pound, or ton of steam, will all be at 100 degrees C, the boiling point.

(Heat of vaporization is 540 calories per gram)

1 unit of steam melts and heats 3 units of ice to its temperature of water’s boiling point.

Steam can be superheated, so I wouldn't take that as a general rule.

 

[ChemEngineer]

Steam can be superheated, so I wouldn't take that as a general rule.

No, you got it backwards. IT IS a general rule, for we are talking about standard pressure.
Superheated steam is a special case which of course introduces an entire new set of
variables..

 

[ChemEngineer]

How many pounds, or ounces, of ice at 0 degrees Celsius will be required to cool one pound of gold at 100 degrees Celsius, just melting all of the ice so that both are at 0 degrees?



The answer is 0.617 ounces of ice.



Water has a heat capacity of 4.18 J/g C degree

Gold has a heat capacity of 0.129 J/g C degree

The heat of fusion of water is 80 times the heat capacity of water, so one gram of gold will heat up 100 degrees with the addition of 12.9 Joules. Ice will melt absorbing 4.18 J x 80 per gram or 334.4 J without changing temperature!

The ratio of 12.9 to 334.4 or .038576 will apply to any respective quantity of gold and ice. So a pound of gold at 100 requires .038576 pound of ice at 0 to cool it. .038576 of 16 ounces is 0.617 ounces of ice.



How many ounces of steam at 100 degrees Celsius will heat up one pound of gold at 0 degrees Celsius, just condensing all the steam so that both are at 100 degrees Celsius?

The answer is 0.0914 ounces of steam.



The heat of vaporization of water at 100 degrees Celsius is 540 times its specific heat which equates to 6.75 times the heat capacity of ice so only 1/6.75 or 0.148148 of the ice in the previous computation is required.



.0617 divided by 6.75 = .0914 ounce

 

[ChemEngineer]

"I have an inferiority complex, but it's not a very good one."



One night my mom told me to go to sleep. I said “I don't know how.” She said you go down to the end of tired and you hang a right. So I went down to the end of tired and, just out of curiosity, I hung a left. There was my mother, saying “I thought I told you to go to sleep!”

"When it rains, I run around and post WET PAINT signs on everything"


There are three kinds of people, those who can count and those who can't


I booked a flight the other day and the clerk asked: How many people will be travelling with you. I don't know it's your plane.

"If you’re not part of the solution, you are part of the precipitate."

I'm a peripheral visionary. I can see the future, but only off to the sides.

"I remember the day the candle shop burned down. Everyone just stood around and sang happy birthday."

I went to get something to eat at a 24 hour convenience store and when I got there a man was locking the place up. So, I asked him "Excuse me isn't this place open 24 hours? Then the man replied, "well yeah, but not in a row!”


You know how a stick in the river, half in and half out of water looks like it bends?
That's why I don’t take baths.


I wish the first word I ever said was 'quote' so right before I died I could say 'unquote’.


Depression is merely anger without enthusiasm.


"I went into a department store the other day, and a man asked, "Can I help you?" I said, "umm yes, do you have anything I would like?" He said, "How do I know what you'd like?" I said, "You started this."


An elderly couple was sitting together, watching their favorite Saturday night TV program.
During one of those commercial breaks, the husband asked his wife:
"Whatever happened to our sexual relations?"
After a long thoughtful silence, the wife, during the next commercial break, replied:
"You know, I don't really know--I don't even think we got a Christmas card from them this year."