Answer:
it is a weak acid
acid
Explanation:
formaldehyde is a weak acid (pK greater than 13),
You would add water to the mixture to dissolve the salt. When the salt is dissolved, you have your sand alone.
To do a balancing to result to a balanced equation, we do elemental balance from each side of the equation. Hence we do separate balances for H, P, O and Ca. In this case, the final balanced equation after balancing elementally is <span>3 Ca(OH)2(aq) + 2 H3Po4(aq) = 6 H2O(l) + Ca3(Po4)2(s)</span>
Answer : The standard enthalpy of formation of ethylene is, 51.8 kJ/mole
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 formation reaction of
will be,

The intermediate balanced chemical reaction will be,
(1)

(2)

(3)

Now we will reverse the reaction 1, multiply reaction 2 and 3 by 2 then adding all the equations, we get :
(1)

(2)

(3)

The expression for enthalpy of formation of
will be,



Therefore, the standard enthalpy of formation of ethylene is, 51.8 kJ/mole