Answer : The change in enthalpy for the following chemical reaction is, -90 kJ
Explanation :
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
The given main reaction is,
The intermediate balanced chemical reaction will be,
(1)
(2)
(3)
Now we will reverse the reaction 2 and then adding all the equations, we get :
(1)
(2)
(3)
The expression for enthalpy of change will be,
Therefore, the change in enthalpy for the following chemical reaction is, -90 kJ
In general, bonds with an electronegativity difference of 0-0.5 are nonpolar covalent, bonds with an EN difference of 0.5-2.0 are covalent, and anything above 2.0 is considered ionic.
To determine the bond types of the pairs of elements, we will need their EN values. We can subtract their EN values to find their EN difference.
H and Br: 2.96-2.20=0.76
Therefore a bond between H and Br would be moderately polar covalent.
Cl and F: 3.98-3.16=0.82
Therefore this bond is moderately polar covalent.
K and Cl: 3.16-0.82=2.34
Therefore this bond is ionic.
Li and O: 3.44-0.98=2.46
Therefore this bond is ionic.
Br and Br: Because these are the same element, meaning that they have the same EN value, we automatically know that their EN difference would be zero. Therefore, this bond is very covalent.
Answer:
given statement is completely true
e.g . water H2O