What Calculations Are Needed to Convert Steam to Water and Ice to Steam?

AI Thread Summary
To convert 400 grams of steam at 200 degrees Celsius to water at 100 degrees Celsius, a total heat loss of -985,000 J is required, which involves cooling the steam and then condensing it into water. The calculations include determining the heat lost during cooling and the latent heat of vaporization. For converting 1 kg of ice at -20 degrees Celsius to steam at 130 degrees Celsius, a heat absorption of 3,100,000 J is necessary, which requires accounting for the energy needed for both phase changes and temperature increases. The process emphasizes that significant energy is needed for phase changes compared to temperature changes. Understanding these calculations involves breaking down the heat transfer into distinct phases for accurate results.
xxiangel
Messages
5
Reaction score
0
Temperature Problems... Confused! please help!

How much heat must be taken away from 400 grams of steam at 200 degrees to change it into water at 100 degrees? (Teacher says answer is -985,000 J)

How much heat must be absorbed by 1 kg of ice at -20 degrees Celcius to change it to steam at 130 degrees? (Answer is 3,100,000 J)


If someone could please show me how to work out these problems, it would be wonderful! Thank you so much! :smile:
 
Physics news on Phys.org
xxiangel said:
How much heat must be taken away from 400 grams of steam at 200 degrees to change it into water at 100 degrees? (Teacher says answer is -985,000 J)
How many moles of H2O in 400 g. of steam? What heat is given off in cooling to 100 deg. C? What is the heat removed from water turning from vapour to liquid?

How much heat must be absorbed by 1 kg of ice at -20 degrees Celcius to change it to steam at 130 degrees? (Answer is 3,100,000 J)
Use the same approach as above.

AM
 
its very very easy...

what andrew said is right...but i will explain it to u...
when steam is to be converted into water it has to lose heat...but one important thing u have to notice is that...when a substance is changing its phase its losing more heat than when a small temperature change occurs...
first let's take steam from 200 to equilibrium..ie 100 degrees...for that heat required is equal to...Q=.4*c*(373-473)...now,steam has to spend some energy to convert steam into water...for that Q1=L*.4...where L is the latent heat of vapourization...then add Q & Q1...remember the added value will be negative as the heat energy is lost here and not gained...remember to convert grams into kilograms for getting answer in SI units...do the same for the second question as well...here Q maybe positive as here we need more energy to convert a solid to vapour...

finally just remember this...we need a lot of energy to change the phase of a substance...and always calculate Q by dividing it into various Qs wherever a phase change is taking place...ok yaaaaaar
 
Last edited:
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
View full post »

Similar threads

Mixing water and ice
Replies
12
Views
912
I try to solve a thermodynamics problem on heat transfer
Replies
3
Views
2K
Heat Transfer. Ice and steam in a container (easy)
Replies
2
Views
4K
1 kg of ice at -20°C is mixed with 1kg steam at 200°C......
Replies
9
Views
7K
Calorimetry: Finding mass of ice, water, steam left
Replies
1
Views
4K
Energy required to make 2.0 kg of steam
Replies
3
Views
2K
Reversible Isothermal Expansion Steam
Replies
2
Views
3K
Question about thermal physics -- Ice cubes melting in water
Replies
8
Views
3K
How much ice to cool down this water?
Replies
17
Views
5K
Finding the Value of M in a Physics Homework Problem
Replies
12
Views
2K

Hot Threads

Recent Insights

Back
Top