Haemoglobin $\left({\mathrm{C}}_{2952}{\mathrm{H}}_{4664}{\mathrm{N}}_{812}{\mathrm{O}}_{832}{\mathrm{S}}_8{\mathrm{Fe}}_4\right.\text{, molar mass }=65248\mathrm{g}/\mathrm{mol})$ is the oxygen carrier in blood. An average adult has about 5.0 L of blood. Every milliliter of blood has approximately $6.0\times {10}^9$ erythrocytes, or red blood cells and every red blood cell has about $3.0\times {10}^8$ haemoglobin molecules. The mass of haemoglobin molecules in an average adult is: $\left({\mathrm{N}}_{\mathrm{A}}=6\times {10}^{23}\right)$