Question

Which solution has the highest concentration of NO₃1-?

a) 0.10 M KNO₃
b) 0.40 M Ca(NO₃)₂
c) 0.30 M Al(NO₃)₃
d) 0.50 M Mg(NO₃)₂

Answer 1

Solution (d) 0.50 M Mg(NO₃)₂ has the highest concentration of NO₃⁻ ions, contributing 1.00 M of nitrate ions per liter when dissolved.

Step-by-step explanation:

To determine which solution has the highest concentration of NO₃⁻ ions, we must consider the number of nitrate ions each compound contributes per mole of substance when dissolved. Let's break down each option:

• (a) 0.10 M KNO₃ contributes 0.10 moles of NO₃⁻ per liter because each formula unit of KNO₃ contains one nitrate ion.
• (b) 0.40 M Ca(NO₃)₂ contributes 0.40 x 2 = 0.80 moles of NO₃⁻ per liter because each formula unit of Ca(NO₃)₂ contains two nitrate ions.
• (c) 0.30 M Al(NO₃)₃ contributes 0.30 x 3 = 0.90 moles of NO₃⁻ per liter because each formula unit of Al(NO₃)₃ contains three nitrate ions.
• (d) 0.50 M Mg(NO₃)₂ contributes 0.50 x 2 = 1.00 moles of NO₃⁻ per liter because each formula unit of Mg(NO₃)₂ contains two nitrate ions.

Thus, the solution with the highest concentration of NO₃⁻ ions is (d) 0.50 M Mg(NO₃)₂, with a total concentration of 1.00 M of nitrate ions.