If a crystal lattice structure is so hard, what causes most ionic compounds to be brittle? A. Applying force, such as striking the crystal with a hammer, can release protons, causing ions of similar charges to align, repel each other, and dissolve the crystal.

B. Applying force, such as striking the crystal with a hammer, can release electrons, causing ions to alter their charges, repel each other, and dissolve the crystal.

C. Applying force, such as striking the crystal with a hammer, can shift one layer of ions, causing ions of different charges to align, repel each other, and fragment the crystal.

D. Applying force, such as striking the crystal with a hammer, can shift ions, causing ions of similar charges to align, repel each other, and fragment the crystal.

Explanation:

The cations and anions are locked tightly into place because of the attraction of their opposite charges - as a result, it's difficult to move the ions and the material is very hard.

d

Explanation:

https://chemistry.stackexchange.com/questions/33322/why-are-so-many-ionic-compounds-brittle

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.

the answer is d. 74.02