Answer is: concentration is 1.3 ppm.
Parts-per-million (10⁻⁶) is present at one-millionth of a gram per gram of sample solution, for example mg/kg.
d(Cu) = 0.0013 g/L; mass concentration of copper.
d(H₂O) = 1.00 g/mL; density of water.
m(H₂O) = V(H₂O) · d(H₂O).
m(H₂O) = 1000 mL · 1 g/mL.
m(H₂O) = 1000 g ÷ 1000 g/kg.
m(H₂O) = 1 kg; mass of water.
m(Cu) = 0.0013 g · 1000 mg/g.
m(Cu) = 1.3 mg; mass of coppper.
concentration = 1.3 mg ÷ 1 kg.
concentration = 1.3 mg/kg.
concentration = 1.3 ppm.
