Question

How many total moles of ions are released when the following sample dissolves completely in water? Enter your answer in scientific notation.
6.18 Ã 10â4g of Ca(NO3)2

Answer 1

Answer:

Total moles of ions are released in water are $1.131\times 10^{-5} mol$.

Explanation:

Mass of calcium nitrate = $6.18\times 10^{-4} g$

Molar mass of calcium nitrate = 164 g/mol

Moles of calcium nitrate = $\frac{6.18\times 10^{-4} g}{164 g/mol}=3.77\times 10^{-6} mol$

$Ca(NO_3)_2(aq)\rightarrow Ca^{2+}(aq)+2NO_3^{-}(aq)$

According to reaction, 1 mole of calcium nitrate gives 1 mole of calcium ions, then $3.77\times 10^{-6}$ moles of calcium nitrate will give:

$1\times 3.77\times 10^{-6} mol=3.77\times 10^{-6} mol$ of calcium ions

According to reaction, 1 mole of calcium nitrate gives 2 mole of nitrate ions, then $3.77\times 10^{-6}$ moles of calcium nitrate will give:

$2\times 3.77\times 10^{-6} mol=7.54\times 10^{-6} mol$ of nitrate ions

Total moles of ions are released :

$3.77\times 10^{-6} mol+7.54\times 10^{-6} mol=11.31\times 10^{-6} mol\approx 1.131\times 10^{-5} mol$