All Questions
Tagged with everyday-chemistry thermodynamics
49 questions
3
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3
answers
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Could an airborne swarm of small insects explode? [closed]
I know that fine-grained organic matter such as flour or pollen can be quite explosive if ignited. It also seems logical to me that the explosiveness of such an organic powder is determined by many ...
- 159
-3
votes
1
answer
284
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If Qc> Kc how can forward reaction can take place
If Qc>Kc then there will be a net backward reaction but still forward reaction will take place. My problem is if Qc>Kc forward reaction will become non spontaneous right. So how can that happen, ...
- 13
-1
votes
1
answer
45
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The edge case of an edge case: Vapor emissions of the descaling agent Sulfamic acid
I am wondering about the following scenario:
What happens if ready bought sulfamic acid descaling (usually 15% cont. + $\ce{H2O}$) is vaporized or at least steam develops while very briefly descaling ...
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1
vote
1
answer
232
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Calculating Enthalpy of formation versus Calculating Enthalpy of a reaction not occurring at standard conditions
My understanding of Hess's law and its use in determining the change of enthalpy of a reaction has been challenged recently.
Up until recently, I thought that the only way to calculate a chemical ...
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0
votes
1
answer
190
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Mechanism of successively melting ice with table salt [closed]
Hi I was reading about how regular sodium chloride in itself can melt ice outside, for example ice on roads during low temperatures. However, I am unsure about the exact details, as I have found some ...
- 471
3
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1
answer
1k
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Why is the boiling point of sugarcane juice lower than the boiling point of water?
As the boiling point is a colligative property, one would expect that the boiling point of sugarcane juice should be higher than pure water because Sugarcane juice contains water (75–85%), non-...
2
votes
1
answer
320
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How does heat transfer between molecules happen in deep?
Inside the container is cold water and outside the container is hot water. B is the microscopic view of container walls .W is water
And A is hot water.
What I have shown is the microscopic view of ...
- 412
1
vote
3
answers
163
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Why water cools from outside to inside?
It is a well-known fact that
Water kept in a container, on cooling, results in freezing with initially at the circumference of surface
(1D), then on the surface (2D) and then throughout the volume (...
- 807
0
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0
answers
295
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Lowering the freezing point of a lipid by adding another lipid
I'm trying to stop bacon grease from congealing in the fridge by adding another lipid with a lower freeze point to it, but I'm not sure how much to add, as I'd like to keep the ratio as bacon-grease ...
- 119
1
vote
1
answer
161
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When reactants are in their transition state, can they go back into their reactants form instead of progressing to form the products? [closed]
When reactants are in their transition state, can they go back into their reactants form instead of progressing to form the products? I don't see any reason why the reaction has to keep progressing ...
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4
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2
answers
609
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Water becomes cold on mixing energy drink [closed]
I noticed that the temperature of water decreases noticeably when I mix an energy drink (Glucon-D) in it. The ingredients mentioned on the pack are majorly glucose (52%) and sucrose (45%). I believe ...
- 6,338
0
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1
answer
777
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Is a person warmed by fire an example of endothermic reaction? [closed]
My chemistry textbook gives the example of a man being warmed by a fire as an endothermic reaction. If the man's body is the system and it is increasing in temperature, how can this be endothermic?
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2
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0
answers
1k
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Which cup of tea cools down more quickly?
There are 2 cups (both cups are identical) of tea which are served at the same temperature. Assume that the walls of the cup to be non-heat conducting. Which cup of tea cools down faster, a full-...
- 163
11
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1
answer
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What are the side effects of adding dry ice to a swimming pool?
My apartment complex pool was closed today due to a resident dumping a large quantity of dry ice into the pool. In the notification from my landlord, they stated:
Dry ice is frozen carbon dioxide ...
- 219
21
votes
1
answer
2k
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If aliens lived in a hydrogen (or any flammable gas) based atmosphere, would they perceive oxygen to be flammable?
Energy, fuel, and oxygen are needed for a fire to burn. In a hydrogen chamber, if there was a pipe spewing small amounts of oxygen, could you light the oxygen on fire as it began to mix with the ...
- 321
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1
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Real life example for second law of thermodynamics
Is there any real life example that can illustrate the Kelvin - Planck's statement of the second law of thermodynamics?
- 23
1
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1
answer
173
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Is it always the case that when a reaction's products are higher in energy than its reactant, then the reaction is not favored?
If this is the case, can you give a brief explanation why is this always the case?
- 85
3
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1
answer
447
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Does benzene vapor react with air in a closed barrel?
If we would have benzene in a closed barrel for quite a while at room temperature, some vapor would form fast due to its volatility, right? But let's say that when the barrel was closed, some air got ...
- 954
2
votes
1
answer
59
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silicon nitride and sCO2
I want to use silicon nitride ball bearings with a reciprocating piston that will be powered by $\ce{CO2}$ liquid heated to $\mathrm{288^oC}$ becoming super critical. That temperature is the maximum ...
- 23
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votes
1
answer
69
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Device to Save Fuel
If I have an electromagnetic device connected to an internal combustion engine, such that the fuel particles passing through the device are "sorted", allowing the fuel to burn better and thus ...
1
vote
1
answer
605
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Will the addition of salt further cool down ice that is already at -30 °C?
I know that ice gets colder when salt is added. But how big is the effect if it is already −30 °C?
Can it cool it down more or does it just work with −1 °C cold ice?
Another question: If I have a ...
- 111
5
votes
2
answers
8k
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Safe endothermic reaction that gets below freezing?
I have a project/idea I am working on but I am only 14 years old and I need some help.
I'm looking for an endothermic reaction that gets below freezing, but the chemicals before the reaction and ...
- 59
3
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2
answers
6k
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Does adding ice to sparkling mineral water extend the 'fizziness' of the solution before the drink goes flat?
To my understanding the carbonated beverage loses its $\ce{CO2}$ content as gas bubbles which gives the drink its 'fizziness'. The loss of $\ce{CO2}$ occurs due to the low solubility of carbonic acid ...
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1
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VT graph thermodynamics
If we have one mole monoatomic ideal gas was taken through process AB as shown in the figure then ∆ S is positive and work is also positive but how can we find the value of work and heat absorbed as ...
- 409
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2
answers
6k
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Is melting of Tar for road construction a reversible change?
In India roads are made up of a black liquid which is prepared by melting a black material(probably coal tar). After cooling the liquid becomes very rigid. Can this solid be converted back to its ...
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4
votes
2
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2k
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Minimum amount of water in pressure cooker
When cooking I would like to know the minimum amount of water I can add to my 6.2 L pressure cooker, worst case, so without any food. At second ring cooking the pressure is 0.8 bar.
I assume I need ...
- 151
2
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3
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How much does a light heat the air around it?
My dad told me to turn off the lights when I'm not using them because it will keep the house cooler. I don't think he is correct that a light can heat up the room. How much of a difference in the ...
- 1,167
1
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0
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43
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Thermodynamic-Fuel and efficiency
Why is the maximum theoretical efficiency of Ar engine higher than that of Nitrogen engine? On a molecular level.
For an Otto Cycle
$\mathrm{Eff} \le\left(1-r^{1-\gamma}\right)$
$\gamma=\dfrac{C_p}{...
- 51
0
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1
answer
473
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Does the temperature of water affect its ability to extinguish fires?
Since water can be either hot or cold, does its temperature affect its ability to extinguish fires?
- 1,491
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1
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When the heat is absorbed by the ice then ice will melt to form liquid water
My new try:
Given data
Energy given by reaction =1690 kJ
Initial temperature = 0 oC
Final temperature = 50 oC
C water = 4.18 Jmol-1 K-1
?Hfus ice = 6.01 kJ*mol-1
Calculate Mass of ice = ?
Ice ...
- 75
11
votes
1
answer
3k
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Is there a chemical reaction which could give off enough heat underwater to cook something?
The mer-people demand cooked food. They don't want to go on land to make it.
Is there a chemical reaction they could use which would create enough heat to cook their food underwater in a safe manner?
- 221
1
vote
2
answers
70
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Exercising to use up energy consumed
Suppose I eat a whole $450~ \rm{g}$ chocolate Easter rabbit. The enthalpy of combustion of chocolate is $−22.4~\rm{ kJ/g}$. One kilogram of body fat contains $39000 ~\rm{kJ}$ of energy. Walking for an ...
- 19
8
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1
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What Causes there to be a Maximum Amount of Salt which can be Dissolved in Water?
When you add salt to water and stir, after a while the salt will no longer dissolve. Why is this?
- 373
16
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4
answers
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Beer freezing after being opened
I am watching the Stoke vs Swansea game, & to be honest, it's pretty boring. So much so, that I've started to wonder why it is that my beer has turned into a slushy after being taken out of the ...
- 263
3
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2
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Why is mercury used in thermometers?
I know it expands when hot and grows compact when cool (that's about all I know), but I suppose many other substances do, too.
Also, and excuses for my ignorance, what the term used to describe the ...
- 139
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3
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Why does hand sanitizer leave your skin feeling cool?
I noticed, and perhaps many others have too, that the application of hand sanitizer (mainly ethanol), leaves one's hands feeling rather chilly after application.
What is responsible for this ...
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2
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2
answers
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Does ice melt faster when submerged in water?
Suppose you have a container with a drain at the bottom full of frozen H2O which you leave a room temperature to melt. Will the ice melt faster if you drain the water as it melts?
I would expect that ...
- 383
0
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1
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endothermic dissolution process
Can anybody give me an example of an endothermic dissolution process, preferably one in which name of the substances involved are easy to remember. I have searched the Web thoroughly but could not ...
- 83
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1
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Is it possible to make liquid nitrogen with a bottle of CO2 gas and a freezer?
I really want to make liquid nitrogen(or oxygen) without using dry ice, a specially made freezer, or other chemicals.
I have a mixture of some sponges, rotten grass, sugar and water, which makes ...
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4
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5
answers
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Homemade reactor for water cooling
Background:
Well, it's summer here in Brazil, and a great way to keep cool is drinking a so called Tereré, and, of course, we do need cold water for that.
Problem: I was looking for endothermic ...
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1
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Strange observation!
Every one have observed that when we pour cool water into a transparent glass (or simply glass), some droplets accumulate on the outside part. Did the droplets come pass through the glass? If they ...
- 2,374
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1
answer
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Why doesn't diffusion take place between immiscible liquids?
If we take a test-tube of bromine and invert an upside-down test tube of air on top of it, it'll diffuse with the air, until the bromine is thoroughly 'mixed' with the air in both test tubes. But why ...
- 3,499
11
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4
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Why calcium chloride is used to melt ice over sodium chloride
I'm not quite sure I understand this. My question is:
Calcium chloride is a salt used widely to melt ice on sidewalks and roads. Explain why one mole of $\ce{CaCl2}$ would be more effective than ...
- 233
8
votes
1
answer
7k
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Is an explosion merely an exothermic reaction?
An exothermic reaction is apparently one that releases energy to it's environment. According to Wikipedia, an explosion is a rapid increase in volume & energy.
Does this mean that an explosion is ...
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2
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3
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Looking for a safe exothermic reaction [closed]
Is there an exothermic reaction which produces 1 to 2 minutes of heat at around 175 degrees Fahrenheit, no toxic gasses and is considered to be more or less safe?
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1
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Why is bread warm at room temperature?
If I buy a loaf of freshly-made bread and leave it out at room temperature for a day or two, when I reach into the bag the air inside is much warmer than the rest of the room. Why?
- 213
22
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3
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7k
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What are the chemical reactions behind fire?
I've always wondered what the chemistry behind fire is. What are the basic chemical reactions behind a simple wood fire, and how do they manifest into this phenomenon?
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2
answers
5k
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Methane seems to dissolve more readily in cold water. Why?
When you are diluting air in the system and/or properly evacuating it, you must consider water temperature. Methane is completely dissolved in water at 42 degrees Fahrenheit (5.5 C) but can be ...
- 841
8
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1
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104
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Retention of surface texture after combustion
Just some while ago I was burning a box of cardboard in my backyard and I saw a very curious phenomenon.
I saw that as the cardboard box started burning it started to curl. Up after a while as I ...
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