<u>Answer:</u> The amount of heat released when 0.211 moles of 
reacts is 554.8 kJ
<u>Explanation:</u>
The chemical equation for the reaction of 
with oxygen gas follows:
The equation for the enthalpy change of the above reaction is:
![\Delta H_{rxn}=[(5\times \Delta H_f_{(B_2O_3(s))})+(9\times \Delta H_f_{(H_2O(l))})]-[(2\times \Delta H_f_{(B_5H_9(l))})+(12\times \Delta H_f_{(O_2(g))})]](https://tex.z-dn.net/?f=%5CDelta%20H_%7Brxn%7D%3D%5B%285%5Ctimes%20%5CDelta%20H_f_%7B%28B_2O_3%28s%29%29%7D%29%2B%289%5Ctimes%20%5CDelta%20H_f_%7B%28H_2O%28l%29%29%7D%29%5D-%5B%282%5Ctimes%20%5CDelta%20H_f_%7B%28B_5H_9%28l%29%29%7D%29%2B%2812%5Ctimes%20%5CDelta%20H_f_%7B%28O_2%28g%29%29%7D%29%5D)
We are given:
Putting values in above equation, we get:
![\Delta H_{rxn}=[(2\times (-1272))+(9\times (-285.4))]-[(2\times (73.2))+(12\times (0))]\\\\\Delta H_{rxn}=-5259kJ](https://tex.z-dn.net/?f=%5CDelta%20H_%7Brxn%7D%3D%5B%282%5Ctimes%20%28-1272%29%29%2B%289%5Ctimes%20%28-285.4%29%29%5D-%5B%282%5Ctimes%20%2873.2%29%29%2B%2812%5Ctimes%20%280%29%29%5D%5C%5C%5C%5C%5CDelta%20H_%7Brxn%7D%3D-5259kJ)
To calculate the amount of heat released for the given amount of , we use unitary method, we get:
When 2 moles of reacts, the amount of heat released is 5259 kJ
So, when 0.211 moles of will react, the amount of heat released will be = 
Hence, the amount of heat released when 0.211 moles of reacts is 554.8 kJ
Answer:
The ranking order of the degree of polarity is HF>HCl>HBr>HI
Explanation:
The degree of polarity of a compound depends on the nature electronegative atom that it contains.
Among Fluorine,chlorine,bromine and iodine the electronegativity of fluorine is highest among all the mentioned atoms.
Due to high electronegativity HF is the most polar than HCl,HBr and HI and the HI have least polarity as its atomic structure is large and electronegativity is lower than fluorine,chlorine and bromine.
Covalent bonding!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
