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I can't present you a movie of electron interactions, but maybe a fuzzy picture. Imagine a metal body (start with copper): the atoms are held in a solid structure - in a sea of electrons! Those loose electrons can be pushed around easily, so we can make wires out of copper and transmit electricity thru them. If you put two different metals together, the sea &...


We consider mixing of $\ce{H2SO4(aq)}$ and $\ce{Ca(OH)2}$ in molar ratio 2:1. Molecular equation version: $$\ce{2 H2SO4 + Ca(OH)2 -> Ca(HSO4)2(aq) + 2 H2O}$$ Eventually if $[\ce{Ca^2+}][\ce{SO4^2-}] = [\ce{Ca^2+}] \cdot K_\mathrm{a2} \cdot \frac {[\ce{HSO4-}]}{[\ce{H3O+}]}> K_{\mathrm{sp,}\ce{ CaSO4}}$ ($\mathrm{p}K_\mathrm{a2}=1.99$): $$\ce{Ca(HSO4)2(...


I am not sure where your solutions come from but 4.42a isn't correct. The products are calcium sulfate and water, and not, as Poutnik points out, $\ce{HSO4-}$. So the molecular formula should finish like this: $\ce{Ca(OH)2(aq) + H2SO4(aq) -> CaSO4(aq) + 2H2O(l)}$ Calcium sulfate is actually pretty insoluble so would normally appear as a precipitate but ...


The molecular formula: $$\ce{ 2 K3PO4 (aq) + 3Ni(NO3)2 (aq) -> Ni3(PO4)2 (s) + 6KNO3 (aq) }$$ The complete ionic formula is: $$ \ce{6K+ (aq) + 2PO4^3- (aq) + 3Ni^2+ (aq) +2NO3- -> Ni3(PO4)2 (s) + 6K^+(aq) + 2NO3^-(aq) }$$ The net ionic formula is: $$ \ce{2PO4^3- (aq) + 3Ni^2+ (aq) -> Ni3(PO4)2 (s) }$$

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