Thinkwell I Fall 2017-Homework assignment #11 Thermoch D: 1458 he combustion of

Question

Thinkwell I Fall 2017-Homework assignment #11 Thermoch D: 1458 he combustion of methane is given by the following equation: CH4(g) + 2 O2(g) CO2(g) + H2O(g) }--890 kJ What is the enthalpy change for 5 moles of methane? -890 kJ +890 kJ -4450 kJ +4450 kJ 11) QID: 1477 Which of the following statements is true? The enthalpy fo The enthalpy from the entha Altitude is a s e reverse positive AH. 12) QID: 1488 +34k -34kJ +788k -788k From the given information, calculate the enthalpy change for the formation of sodium chloride. Na+(g) + Cr@-NaCl(s) H = ? Na(g) + Cl(g) Na+(g) + Cl-(g) -+147 kJ Na(s) + ½ Cl2 (g) Na(g) .+ Cl(g) -+230 kJ Na(s) + ½ Cl2(g)- NaCl(s) AH=-411kJ

Explanation / Answer

Solution:- (10) The given equation is...

CH4(g) + 2O2(g) -----> CO2(g) + 2H2O(g) delta H = -890kJ

from the balanced equation, 890 kJ of heat is released by the combustion of 1 mol of methane(CH4).

So, the that would released from the combustion of 5 moles of methane would be...

5 mol x (-890 kJ)/1mol = -4450 kJ

(12) It is based on Hess's law.

We need to calculate the enthalpy change for the equation, Na+(g) + Cl-(g) ----> NaCl(s)

We would try to make this equation from the given equation..

Na+(g) and Cl-(g) are present in first equation so let's flip the first equation. when an equation is flipped then sign of delta H is also changed.

Na+(g) + Cl-(g) ----> Na(g) + Cl(g) delta H = -147 kJ

Now, we want the product that is NaCl(s). This is present in last equation so let's write that.

Na(s) + 1/2Cl2(g) ----> NaCl(s) delta H = -411 kJ

To get rid of Na(s). It's present in second equattion, so let's flip the second equation.

Na(g) + Cl(g) ----> Na(s) + 1/2Cl2(g) delta H = -230 kJ

let's add all these three equations...

Na+(g) + Cl-(g) ----> Na(g) + Cl(g) delta H = -147 kJ

Na(s) + 1/2Cl2(g) ----> NaCl(s) delta H = -411 kJ

Na(g) + Cl(g) ----> Na(s) + 1/2Cl2(g) delta H = -230 kJ

-------------------------------------------------------------------------------------------

Na+(g) + Cl-(g) ----> NaCl(s) delta H = -788 kJ

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

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