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Given that

P(g) + 3Cl(g) = PCl3(g) energy change = -983kjmol-1
P(s) + 3/2Cl2(g) = PCl3(g) energy change = -305kjmol-1
P(s) = P(g) energy change = +314kjmol-1

calculate the following bond energies:

a) P-Cl in PCl3

b) Cl-Cl in Cl2

i really have absolutley no idea what to do so some help would be much appreciated

2. (Original post by Aleisha1)

Given that

P(g) + 3Cl(g) = PCl3(g) energy change = -983kjmol-1
P(s) + 3/2Cl2(g) = PCl3(g) energy change = -305kjmol-1
P(s) = P(g) energy change = +314kjmol-1

calculate the following bond energies:

a) P-Cl in PCl3

b) Cl-Cl in Cl2

i really have absolutley no idea what to do so some help would be much appreciated
a) Look at the first equation and consider the definition of bond energy ...
3. (Original post by charco)
a) Look at the first equation and consider the definition of bond energy ...
Hi sorry i still dont understand. i have nothing in my notes or text book telling me how to do this so i am basically starting from scratch :s
4. (Original post by Aleisha1)
Hi sorry i still dont understand. i have nothing in my notes or text book telling me how to do this so i am basically starting from scratch :s
The bond energy is the energy required to break 1 mole of specific bonds giving gaseous atoms.

Look again at the first equation and ask yourself "what is happening to get from reactant to products?" ...
5. (Original post by Aleisha1)

Given that

P(g) + 3Cl(g) = PCl3(g) energy change = -983kjmol-1
P(s) + 3/2Cl2(g) = PCl3(g) energy change = -305kjmol-1
P(s) = P(g) energy change = +314kjmol-1

calculate the following bond energies:

a) P-Cl in PCl3

b) Cl-Cl in Cl2

i really have absolutley no idea what to do so some help would be much appreciated
What bonds (notice plural) are you forming in reaction one ? How much energy is being released to form these ? Therefore how much energy would be required to BREAK one of them ?
Bond enthalpies are always quoted as positive as the definition is to break bonds.
Question b you'll need to piece together reactions 2 and 3.
6. (Original post by charco)
The bond energy is the energy required to break 1 mole of specific bonds giving gaseous atoms.

Look again at the first equation and ask yourself "what is happening to get from reactant to products?" ...
thanks i think i get it now
7. (Original post by Spoogle)
What bonds (notice plural) are you forming in reaction one ? How much energy is being released to form these ? Therefore how much energy would be required to BREAK one of them ?
Bond enthalpies are always quoted as positive as the definition is to break bonds.
Question b you'll need to piece together reactions 2 and 3.

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