A zinc coating is added to the surface of a tin component to provide corrosion protection to the tin. Assume that the coating adheres to (physically contacts) the underlying tin. A small region of the zinc coating is chipped, but the remainder of the coating remains intact. What do you expect will happen to the coating and the exposed tin in the presence of salt water and oxygen?

In the presence of salt water and oxygen the coating will not corrode. As long as zinc coating is present and remains intact corrosion is not possible.

Explanation:

Here it is given that a tin is present so firstly tin is made of a chemical element

which belongs to carbon family in periodic table of group 14.

It is a silvery,soft, white metal with a bluish tinge.

Now the covering which is been done on the tin is Zinc.

so, zinc is known to be served as a sacrificial coater.

Their is an amazing reason behind zinc coating being so effective and intact  i.e. Its own corrosive properties are such that it stops corrosion.

Their is a process which is known as a galvanic corrosion which refers to that "ZINC" defers to the metal  to which it is protecting.

It is even more electrochemically active than iron itself.

Here, it is mentioned that zinc coating gets chipped but the coating remains intact. So, if the zinc is not removed from the tin's surface it will not get corroded when it is exposed to salt water and oxygen.

answer: the enthalpy of the overall chemical reaction is +87.88 kj or +88 kj.

according to hess's law, the overall enthalpy of a reaction is the difference between the sum of enthalpy values of all the products and the sum of enthalpy values of all the reactants.

δh(reaction) = ∑nδh(products) - ∑nδh(reactants)

δh(reaction) = [δh +δh] - [δh]

δh(reaction) = [1(-287.02) + 1(0) ] - [1(-374.9)] kj = +87.88 kj

here, δh (pcl3) = -287.02 kj, δh(cl2) = 0, δh(pcl5) = -374.9 kj

therefore, enthalpy of the overall reaction is +87.88 kj or +88 kj.