Question

the coulombic forces that hold the ions together in an ionic solid are characterized in terms of the lattice energy of the crystal. as we have seen, high lattice energy results in high melting points. high lattice energy also results in lower solubility in water. for example, the mineral calcite is calcium carbonate, ca²⁺ co₃²⁻, also known as limestone. limestone is not very water soluble, which is a good thing, otherwise limestone buildings would dissolve when it rains! (limestone does start to dissolve in acidic water, but we are discussing pure water here). given that information above, and assuming that water solubility was the only important factor to consider, which of the following minerals would you not want to make a building out of in a rainy climate? (note that mineral names almost always end in \ite\) calcite - ca²⁺ co₃²⁻ bromellite - ba²⁺ o²⁻ karobbite - k⁺ f⁻ ceresite - sr²⁺ so₄²⁻ dont test me yet, i am trying to gain an understanding before attempting to answer this question.

Explanation:

The key is to identify a mineral with low water - solubility. Ceralcite ($Sr^{2+}SO_{4}^{2 - }$), Karobbite ($K^{+}F^{-}$), Bromellite ($Ba^{2+}O^{2 - }$) and Calcite ($Ca^{2+}CO_{3}^{2 - }$) are considered. Calcite is a main component of limestone which dissolves in acidic water. Among them, Bromellite is likely to have relatively low water - solubility due to its ionic composition and lattice energy characteristics compared to the others which might be more reactive or soluble under certain conditions.

Answer:

Bromellite - $Ba^{2+}O^{2 - }$