Physics__chemistry_of_water_in_contact_with_molten_metal.pdfVIP

International Manganese Institute 1 The Physics Chemistry of Water in contact with Molten Metal Dr Doreen McGough OHES Manager, IMnI IMnI’s 2nd safety workshop: Sponsored by Eramet Date: 2-3 May 2011 International Manganese Institute 2 Topics ? Water ? Molten Metal ? Water’s reaction in contact with Molten Metal ? Summary/conclusion International Manganese Institute 3 Characteristics of Water ? Depending on the temperature water can exist in different states namely; - water is a liquid at ambient conditions - Water is a solid in the form of ice, frost etc at very low temperatures - Water is a gas in the form of water vapor or steam at 100 deg C International Manganese Institute 4 Water – The Chemistry ? Water is a chemical substance with a chemical formula – H2O ? Its molecule contains one oxygen and two hydrogen ? The atoms connected by covalent bonds- a molecule ? The molecules are connected to each other by a Hydrogen bonds via bi-polar interaction International Manganese Institute 5 Water – The Physics ? As H2O changes state, the amount of heat energy required to change its temp in the same state is referred to as the specific heat – expressed in calories. ? The specific heat of liquid water is 1.0 calories while it is 0.5 calories for ice. ? If we look at a graph of temp Vs heat input, we can follow the change from ice at -100C to water vapor at 150 deg C. ? In order to get the ice to the melting temp, it requires 100*0.5 or 50 calories. International Manganese Institute 6 Molten Metal ? Molten metal can simply be defined as metal in its liquid state ? At temp’s of 300 to ca 2000°C, the solid metal or the alloy becomes liquid/fluid ? Fluid life depends on several other physico- chemical properties ? Engineers and occupational health scientists must understand these properties in order to reduce risk International Manganese Institute 7 Factors that affect the Liquid State of Metals ? Temperature ? Viscosity ? Surface tension