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1.) When 1kg of water at 20.0 C changes to ice at -20.0 C is heat released or ab

ID: 1414106 • Letter: 1

Question

1.) When 1kg of water at 20.0 C changes to ice at -20.0 C is heat released or absorbed? How much heat?
2.) When 1kg of water at 20.0 C changes to steam at 120.0 C is heat released or absorbed? How much heat?
3.) At what temperature is the RMS speed of H2 equal to RMS speed of O2 at 300K? 1.) When 1kg of water at 20.0 C changes to ice at -20.0 C is heat released or absorbed? How much heat?
2.) When 1kg of water at 20.0 C changes to steam at 120.0 C is heat released or absorbed? How much heat?
3.) At what temperature is the RMS speed of H2 equal to RMS speed of O2 at 300K?
2.) When 1kg of water at 20.0 C changes to steam at 120.0 C is heat released or absorbed? How much heat?
3.) At what temperature is the RMS speed of H2 equal to RMS speed of O2 at 300K?

Explanation / Answer

1 )

given

m = 1 kg

C = 4180 J.kg/K

temperature dT = T1 - T2 = 20-(-20)

= 40 C

Q = m X C X dT

= 1 X 4180 X 40

= 167200 J

Q = 1.672 X 105 J

heat released Q = 1.672 X 105 J

2 )

dT = 120-20 = 100 C

Q = m X C X dT

= 1 X 4180 X 100

Q = 4.18 X 105J heat absorbed

3 )

T / mH2 = 300 / mO2  

T / 2 = 300 / 32

T = 2 X 9.375

T = 18.75 K