A. Calculate the standard enthalpy change for the reaction 2A+B2C+2D Use the fol
ID: 916938 • Letter: A
Question
A.
Calculate the standard enthalpy change for the reaction
2A+B2C+2D
Use the following data:
Express your answer to three significant figures and include the appropriate units.
B.
How much heat is required to warm 1.60 L of water from 26.0 C to 100.0 C? (Assume a density of 1.0g/mL for the water.)
C.
A 2.67 g lead weight, initially at 11.0 C, is submerged in 8.18 g of water at 52.4 C in an insulated container.
What is the final temperature of both the weight and the water at thermal equilibrium?
Express the temperature in Celsius to three significant figures.
Substance Hf(kJ/mol) A -225 B -419 C 195 D -495
Explanation / Answer
2A + B <-> 2C + 2D
HRxn = Hprod - Hreact
Hrxn = 2*195 + 2*-495 - (2*-225 -419) =269 kJ/mol
b)
Q = m*Cp*(Tf-Ti)
Q = 1600*4.184*(100-25) =502080 J
c)
m = 2.67 g of Lead
Cp lead = 0.128 J/gC
T = 11
m = 8.18 g of water
t = 52.4
Cp = 4.184
Q = -Q
m*Co*(TF-t1) = -m*Cp*(Tf-T2)
2.67*0.128*(Tf-11) = -8.18*4.184*(Tf-52.5)
Tf-11 = -100.143(Tf-52.5)
Tf-11= -100.14Tf + 5257.4
101.14Tf = 5257+11
Tf = 52.08°C
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