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Section 3 : Physical Data
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WHMIS: What You Need to Know
11. The Material Safety Data Sheets (MSDSs)
The physical state, appearance and odour of acetone may aid in its identification.
The boiling point of acetone is 56.6 C. This is the temperature at which acetone changes from a liquid to a gas, at normal atmoshpheric pressure. Below this temperature, lqiuid acetone can evaporate to form a vapour. As acetone approaches the boiling point, the change from liquid to vapour/gas is rapid and vapour concentrations in air can be very high.
The freezing point of acetone is -94.7 C. This is the temperature at which liquid acetone becomes solid, at normal atmospheric pressure. This information is important for storage and handling purposes. For example, a frozen material may burst a container. Also, a change of physical state could alter the hazardous nature of the material.
The odour threshold of acetone is 100-150 ppm. This is the level, in parts per million, at which the odour becomes noticealbe. Compare this to the exposure limit; if it is well below, for example, odour can be sued to warn of a problem with your air purifying respirator. Odour, however, must not be used to determine safe/unsafe conditions (the presence of other odours may confuse the sense of smell, workers may become used to the odour, or the chemical may numb the sense of smell).
The vapour pressure of acetone is 181.7 mmHg at 20 Celsius. This is the pressure of acetone vapour in equilibrium with its liquid form. Vapour pressure is a measure of the tendency of a material to form a vapour. The higher the vapour pressure, the higher the potential vapour concentration.
The evaporation rate of acetone is 7.7 at 20 C. This is the rate at which liquid acetone changes to a vapour. Evaporation rate is a measure of how quickly the material becomes a vapour at a specified temperature, usually normal room temperature. Generally, the rate is given in comparison to a chemical which evaporates quickly, in this case butyl acetate. Acetone evaporates at a rate of 7.7 times that of butyl acetate.
The vapour density of acetone is 2. This is the density of acetone vapour compared to the density of an equal amount of air. Acetone vapour is heavier than air and thus can accumulate at ground level.
The volatility of acetone is 100%. This means that all of the material will evaporate if given enough time.
The specific gravity of acetone is 0.79 at 20 C. This is the density of liquid acetone compared to the density of an equal amount of water. When the specific gravity of a substance is greater than 1.0 it will sink in water, when less, it will float. This information is important in planning spill clean-up and fire fighting procedures.
The coefficient of oil/water distribution is the ratio of the solubility of the chemical in an oil to its solubility in water. It also indicates how readily a chemical can be absorbed into or stored in the body.
The solubility of acetone is 100%. This represents the ability of acetone to dissolve in water or another liquid. The information is also important in planning spill clean-up and fire fighting procedures.
pH is a measure of the acidity or basicity (alkalinity) of a material when dissolved in water. Materials with pH values of 0-2 or 11.5-14 are classed as corrosive.
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