Thread: Introduction to Thermodynamics

Two Basic Questions:

1. A kettle holding 1lt. of water is boiling. Assuming water is evaporating at a constant evaporation rate of 1g/min, determine how long it will take for the kettle to dry out.

2. Another kettle holding 1lt. of water and 20g. of salt is also boiling. Again water evaporates at a rate of 1g/min. This time you are asked to derive a mathematical relationship for how the salt concentration in the kettle changes with respect to time.

Starting from these two basic questions, we can discuss some basic topics of Thermdynamics, exactly conservation of mass and energy. These two questions are about material balance in open and closed systems.

20-25 views and no any answer, no any try-to-do?

1) water has the ratio 1kg/1 litre

so in 1 litre of water you have 1000g
1 gram per minute,
you can do the maths.

As for the second question, you should get a hyperbolic graph? 1/x and all that?

20-25 views and no any answer, no any try-to-do?

Too trivial. Where are you really going with this?
We'll wait for the good stuff.


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Now this calls for my high school drop out physics skills!

Water at 100C has a density of ~0.958g/cm3 which should give one liter a weight of 958g. At the rate of 1g/m the formula should be 20/(978-t) where t is time in minutes.

8)