We recognize this as a
dilution problem because it mentions two concentrations of the same
substance and refers to the dilution of a more concentrated solution to
form a more dilute solution. We can therefore use the dilution equation.

M_{C} = 15.8 M V_{C} = 25.0 mL
M_{D} = ? V_{D} = 1.50 L

M_{C}V_{C}
= M_{D}V_{D}

**=
0.263 M HNO**_{3}

Notice that
a unit conversion is necessary to make our units cancel to yield a
molarity unit.

Alternatively, we could work the problem
using the dimensional analysis technique: