Question

PbO can be formed from lead metal and oxygen gas

Pb+O₂ $\rightarrow$ PbO

Use the follwing reactions to determine the standard enthalpy change when 1 mole of PbO is formed from lead metal and oxygen gas

PbO+C $\rightarrow$ Pb+CO dELTA H=107KJ

2C+O₂ $\rightarrow$ 2CO DELTA H=-222KJ

Answer 1

first we multiply the first equation by 2 and then subtracting the second equat

2PbO+2C= 2Pb+2COion from it, we get

- 2C+O2 = 2CO

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2PbO - O2 = 2Pb

therefore, 2Pb+O2 = 2PbO (this is the correct equation. yours is not balanced.)

the standard enthalpies also get subtracted in the process.

delta H of formation of PbO=(2x107 KJ)-(-222 KJ)

=436 KJ