1. what is isomorphous substitution? 2. clay surfaces how many moles of calcium are required in the interlayer spacing of the following montmorillonite (1 mole) to ensure a net-zero charge (ie what is x)? montmorillonite: cax (siral os) (alo osmgs75fe0.2)。20(oh) 4 assume the valence of iron is +2 (i. e fe2) to answer this question think about i) what a mole is (1st year foundations 2 subject) and how the moles are represented in the montmorillonite equation ii) the valence of each cation - ca, si, al, mg, fe, o and oh i) the charge contributed by each element in the montmorillonite (multiply the number of moles x the charge) the total charge of the montmorillonite excluding the ca. the charge of the ca and therefore how many moles are required to balance iv) above. iv) v)