1a)The enthalpy change for the reaction below at 25oC is -1,850 kJ (per mole of

Question

1a)The enthalpy change for the reaction below at 25oC is -1,850 kJ (per mole of C9H20). What is the internal energy change for the reaction at 25oC?

9 CO(g) + 19 H2(g) --> C9H20(l) + 9 H2O(l)

Enter your answer in kJ (per mole of C9H20), rounded to the nearest kilojoule.

1b)When a 8.37-g mixture of methane, CH4, and ethane, C2H6, is burned in oxygen at constant pressure, 445.8 kJ of heat is liberated. What is the percentage by mass of CH4 in the mixture? The standard enthalpies of combustion for CH4 and C2H6 are -890.3 kJ mol-1 and -1569.7 kJ mol-1, respectively.

Use atomic masses accurate to four significant digits in your calculations.
Enter your answer with 2 significant digits.
Enter only numbers in your answer. (

Explanation / Answer

n =change in number of moles of gaseous state components =0-(19+9) = -28

H=U +nRT

U = H -nRT = -1850 -(-28*0.008314*298) =-1850 +69.37 = -1780.63 kJ

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.