Magnesium oxide Chemical Properties CAS: 1309-48-4 MF: MgO MW: 40.3 EINECS: 215-171-9 Mol File: 1309-48-4.mol Melting point 2852 �°C (lit.) Boiling point 3600 �°C refractive index 1.736 Fp 3600 C solubility 5 M HCl: 0.1 M at 20 C, clear, colorless form Nanopowder color White Specific Gravity 3.58 PH 10.3 (H2O, 20�ºC)(saturated solution) Water Solubility 6.2 mg/L (20 �ºC), reacts Sensitive Air Sensitive max 260 nm Amax: 0.040 Merck 145,677 Exposure limits ACGIH: TWA 10 mg/m3