What is the molarity of CO2 in a liter of ocean water, with density of 1027 kg/m^3, at 25 *C that contains approximately 280 ppm of CO2?

Molar mass of CO₂ = (12.0 + 16.0×2) g/mol = 44.0 g/mol
Density of ocean water = (1027 × 1000 g / 1000 L) = 1027 g/L

Total mass of 1 L of ocean water = (1 L) × (1027 g/L) = 1027 g
Mass of CO₂ in 1 L of ocean water = (1027 g) × (280/1000000) = 0.2876 g
Moles in CO₂ in 1 L of ocean water = (0.2876 g) / (44.0 g/mol) = 0.00654 mol

Molarity of CO₂ = (0.00654 mol) / (1 L) = 0.00654 M

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OR:
(1027 × 1000 g ocean water / m³) × (280 g CO₂ / 1000000 g ocean water) × (1 m³ / 1000 L) × (1 mol CO₂ / 44.0 g CO₂)
= 0.00654 mol CO₂ /L
= 0.00654 M CO₂