The Force Between Two Charged Particles Can Be Calculated Using $$F = k \frac { q _ { 1 } q _ { 2 } } { r ^ { 2 } }$$

Essay

The force between two charged particles can be calculated using the following equation: $$F = k \frac { q _ { 1 } q _ { 2 } } { r ^ { 2 } }$$
where
$$\begin{array} { l } F = \text { force in newtons } \\G = \text { electrostatic constant } \\q _ { 1 } = \text { charge of particle } 1 \text { in coulombs } \\q _ { 2 } = \text { charge of particle } 2 \text { in coulombs } \\r = \text { distance between particles in meters }\end{array}$$
What is the appropriate unit for $k$ if the preceding equation is to be homogeneous in units?