It was warmer 1000 and 2000 years ago


#82

Wish I could edit. Dissolve 2.00 grams of salt in 20.00 grams of water. the result is 21.98 grams. there we go.


#83

Climate has never been stable, other than being consistantly fluctuating at an inconsistent rate.
Since time began. There have been too many variables for it to be otherwise.
The temperature of the sun has changed. The orbits have changed, the continents have moved, changing the weather patterns. The jet streams move. And on it goes.
If you want to say this year is different than 5 years ago, fine.
It is a blink of an eye, and it makes no real difference.
But go ahead, say whatever makes you feel better.


#84

Cool. When did time begin?


#85

How long is a blink of an eye?


#86

Which orbits have changed?


#87

What makes you feel better? At least my wife makes me know what feels better. But she’s not really interested in orbits and stuff.


#88

I’m trying to figure out where your lassie faire attitude leaves us.

We are changing the climate rapidly and in an uncontrolled manner. This is not natural and is not cyclical. It’s not the sun. It’s not our orbit. It’s not the continents. It’s us.

The Earth was warmer millions of years ago sure. The Earth will probably survive our climate meddling.

Will we?


#89

Salt water weighs more per volume than fresh water, and adding salt to fresh water does not change its volume. Didn’t you learn that in 7th grade?

ETA Sorry, I did not see your correction posts until I posted this one.


#90

All of them.


#91

Yeah. I wasn’t clear. So my question was: If 2.00 grams of salt is dissolved in 20.00 grams of water and the resulting mass is 21.98 grams, did the mass change?


#92

Grams are mass.

What is your point?


#93

Yes. I’m talking about mass. It’s a mass problem.


#94

So what is your point?


#95

Did mass change?


#96

I’m still not getting your point. What does the solubility of a salt in a liquid have to do with the topic?


#97

Sorry if I’m misunderstood. I am not talking about solubility. I am talking about mass. So again, I offer up a more specific description of the problem: If 2.00 g of salt is dissolved in 20.00 g of water and, when dissolved, the resulting mass is 21.98 g, is your conclusion is that mass decreased?


#98

No. Some of the mass was transformed into energy.

But again … what does this have to do with the topic?


#99

A couple of things. This is not strictly a question about mass. It is a typical 8th-grade problem involving uncertainty. And more broadly, uncertainty in measurement, scientific or otherwise. Apply to any topic you like.

All measurements are subject to uncertainty, which is limited by instrumentation. A standard electronic balance that reports mass to the 0.01 g, usually has an uncertainty of +/- 0.01 g, unless it is worse than advertised (by the way, that can be tested). So, if two measurements are involved in an operation involving subtraction or addition, the uncertainty is more-or-less doubled. So a change in mass of 0.02 g is not sufficient to conclude that the mass changed. Ergo, no evidence that mass changed. And in any case that would violate the Law of Conservation of Mass. It is simply attributable to experimental error.


#100

And endothermic reaction.

… or is it exo? :thinking:

It’s been too many years since I took Chemistry.


#101

Yeah Samm. It is endothermic. And admittedly it was kind of a trick question. So, I had this 5th grade teacher come to me and said: “We can’t teach this kid anything more, can you do something for him.” He was nine years old. So I said bring him up. He came with his mom and the books he was reading, which were about relativity. So I asked the kid, suppose you have two lead boxes on an equal-arm balance and and the arm was horizontal. Suppose you could heat up one of the lead boxes. Would the arm stay balanced, would it go down, or would it go up?

Would would you say?

He said that the heated box pan would go down. I asked him why. He said that heat translates to motion, and that relative motion increases mass. It was a relativistic argument. He was right.

Only one of two geniuses I’ve taught in 31 years,