
As long as the equation in question can be expressed as the sum of the three equations with known enthalpy change, its
can be determined with the Hess's Law. The key is to find the appropriate coefficient for each of the given equations.
Let the three equations with
given be denoted as (1), (2), (3), and the last equation (4). Let
,
, and
be letters such that
. This relationship shall hold for all chemicals involved.
There are three unknowns; it would thus take at least three equations to find their values. Species present on both sides of the equation would cancel out. Thus, let coefficients on the reactant side be positive and those on the product side be negative, such that duplicates would cancel out arithmetically. For instance,
shall resemble the number of
left on the product side when the second equation is directly added to the third. Similarly
Thus
and

Verify this conclusion against a fourth species involved-
for instance. Nitrogen isn't present in the net equation. The sum of its coefficient shall, therefore, be zero.

Apply the Hess's Law based on the coefficients to find the enthalpy change of the last equation.

Nitrous Acid.
Hyponitrous acid: H2N2O2
Nitric acid: HNO3
Pernitric acid: HNO
Answer : The isoelectronic groups are:



Explanation :
Isoelectronic : It is defined as the compound or molecule having the same number of electrons and the same number of electronic structure.
- The element is helium. The number of electrons are 2.
- The element is beryllium. The number of electrons are 4. The number of electrons in
= 4 - 2 = 2 - The element is lithium. The number of electrons are 3. The number of electrons in
= 3 - 1 = 2 - The element is nitrogen. The number of electrons are 7. The number of electrons in
= 7 + 3 = 10 - The element is neon. The number of electrons are 10.
- The element is sulfur. The number of electrons are 16. The number of electrons in
= 16 + 2 = 18 - The element is magnesium. The number of electrons are 12. The number of electrons in
= 12 - 2 = 10 - The element is titanium. The number of electrons are 22. The number of electrons in
= 22 - 4 = 18 - The element is potassium. The number of electrons are 19. The number of electrons in
= 19 - 1 = 18
The isoelectronic groups are:



Answer:
HClO (l) → H⁺ (aq) + ClO⁻ (aq)
proton and hypochlorite.
Explanation:
HClO (Hypochlorous acid)
This is a weak acid that can be dissociated as this:
HClO (l) → H⁺ (aq) + ClO⁻ (aq)
proton and hypochlorite.
It is a weak acid, so it can adopt a Ka for its equilibrium
HClO + H₂O ⇄ H₃O⁺ + ClO⁻ Ka
Molar mass = 52.46 g/m