Answer:
The outermost shell of helium for example is filled with only two electrons. Hydrogen and lithium become stable by acquiring the electronic configuration of the nearest inert gas, which is helium. This is the duplet (or duet) rule.
Explanation:
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The chemical formula for calcium hydroxide is Ca(OH)₂ and that of nitric acid is HNO₃. By these chemical formula it can be deduced that the number of equivalents per mole of Ca(OH)₂ is 2 because of 2 OH⁻ and for HNO₃ is 1 because of H⁺.
For the neutralization reaction, the number of equivalents should be equal.
V₁n₁ = V₂n₂
Substituting the known values and with the incorporation of the concept above,
(V₁)(0.0250 mol/L)(2 equivalents/mol) = (33.50 mL)(0.020 mol/L)(1 equivalent/mol)
V₁ = 13.4 mL
Hence, the volume of calcium hydroxide needed is approximately equal to 13.4 mL.