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what is the energy change, ??, of a system if a chemical reaction \'ransfers 35.

ID: 636462 • Letter: W

Question

what is the energy change, ??, of a system if a chemical reaction 'ransfers 35.00 kJ of heir to the surroundings while it causes the expansion of a 1500 L vessel to 3 509 L against o prsssre of 550 atmospheres? 1L-atm 101.3 J 8. 9. A 15.0 g metal sample at 25.0 °C has 250 J of heat added to it. The specific hest of the metal is 0.445 J/g°C What is the final temperature? 10. When 1500. J of heat is added to 250. g of a metal, its temperature is raised by 29 °c. What is she specific heat capacity of the metal?

Explanation / Answer

8)

W = -Pext(Vf-Vi)

P = 5.0atm

Vi = 1.5 L

Vf = 3.5 L

put values in above expression

W = -Pext(Vf-Vi)

W = -5.0atm (3.5L - 1.5L)

W = -10.0 atm.L

W = -10.0 *101.3 J

W = -1013 J

W = -1.013 KJ

WE HAVE:

Q = -35.00 KJ

use:

?E = Q + W

?E = (-35.0 KJ) + (-1.013 KJ)

?E = -36.0 KJ

Answer: -36.0 KJ

9)

Given:

Q = 250 J

m = 15 g

C = 0.445 J/g.oC

Ti = 25 oC

use:

Q = m*C*(Tf-Ti)

250.0 = 15.0*0.445*(Tf-25.0)

Tf -25.0 = 37.45 oC

Tf = 62.5 oC

Answer: 62.5 oC

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