Energy of sublimation of na(s) = 97 kj/mol bond energy of hbr = 363 kj/mol ionization energy of na(g) = 496 kj/mol electron affinity of br(g) = –324 kj/mol lattice energy of nabr(s) = –781 kj/mol bond energy of h2 = 432 kj/mol calculate the net change in energy for the following reaction: 2na(s) + 2hbr(g) → 2nabr(s) + h2(g)

Pegmatites are igneous rocks in which the individual minerals are very large. typically, the minerals are all light-colored quartz, feldspar and muscovite. if you were given a black and white photograph of a pegmatite in a quarry (where the rock has been blasted and broken), what physical properties could you use to identify those three minerals in this hypothetical photo? describe each mineral and the specific diagnostic properties. be specific.