Freezing point and melting point
Title
Freezing and Melting Point
Objectives
1. To gain proficiency in constructing a graph and plotting data points.
2. To determine the freezing points of a compound from the graph of decreasing temperature versus time.
3. To determine the melting points of a known and unknown compound.
Introduction
Physical changes are the changes in the physical properties of a substance (Moore, Stanitski & Jurs, 2009). Freezing point is the fixed temperature at which a pure liquid converted into crystalline solid. Melting point is the fixed temperature at which a crystalline solid converted to a liquid (Ebbing & Gammon, 2010). The melting point of a solid and the freezing point of its liquid is the same. It is the temperature at which the rate of freezing of its liquid is the same as the rate of melting of a solid under a given applied pressure (Whitten, Davis & Peck, 2009). A change of state involves the removal energy or addition energy to or from the substance (Ebbing & Gammon, 2010).
In this experiment, the temperature of the stearic acid is needed to plot on a graph. When the stearic acid turned from liquid into solid and the freezing point of the stearic acid can be determined from the graph. The melting points of stearic acid and unknown compound can also be determined in this experiment.
If the temperature of the stearic acid/time data plots on the graph, cooling curve will occur. If the temperature drops and remains unchanged at a certain point, then the freezing point will be found in the graph. If the stearic acid and unknown substance heat from solid form and turn to liquid form, then the melting point of the stearic acid and unknown substance can be found. If the melting point of the unknown compound is determined, then the unknown compound can be found.
Materials and Apparatus
1. Wire gauze
2. Thermometer
3. Test tube
4. Mortar and pestle
5. 110 oC thermometer with split cork
6. Capillary tubes
7. Rubber bands
8. 400 mL beaker
9.
Freezing and Melting Point
Objectives
1. To gain proficiency in constructing a graph and plotting data points.
2. To determine the freezing points of a compound from the graph of decreasing temperature versus time.
3. To determine the melting points of a known and unknown compound.
Introduction
Physical changes are the changes in the physical properties of a substance (Moore, Stanitski & Jurs, 2009). Freezing point is the fixed temperature at which a pure liquid converted into crystalline solid. Melting point is the fixed temperature at which a crystalline solid converted to a liquid (Ebbing & Gammon, 2010). The melting point of a solid and the freezing point of its liquid is the same. It is the temperature at which the rate of freezing of its liquid is the same as the rate of melting of a solid under a given applied pressure (Whitten, Davis & Peck, 2009). A change of state involves the removal energy or addition energy to or from the substance (Ebbing & Gammon, 2010).
In this experiment, the temperature of the stearic acid is needed to plot on a graph. When the stearic acid turned from liquid into solid and the freezing point of the stearic acid can be determined from the graph. The melting points of stearic acid and unknown compound can also be determined in this experiment.
If the temperature of the stearic acid/time data plots on the graph, cooling curve will occur. If the temperature drops and remains unchanged at a certain point, then the freezing point will be found in the graph. If the stearic acid and unknown substance heat from solid form and turn to liquid form, then the melting point of the stearic acid and unknown substance can be found. If the melting point of the unknown compound is determined, then the unknown compound can be found.
Materials and Apparatus
1. Wire gauze
2. Thermometer
3. Test tube
4. Mortar and pestle
5. 110 oC thermometer with split cork
6. Capillary tubes
7. Rubber bands
8. 400 mL beaker
9.