Chemistry Class Exercise

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Class exercise:
1) What are the sources of carbon dioxide in water?
The sources of carbon dioxide in water are microbial decay of organic matter and the equilibrium of dissolved carbon dioxide with gaseous carbon dioxide in the atmosphere. 2) Solubility of oxygen in water is affected by several factors and what are these factors? Solubility of gases in water is affected by the temperature of water and the pressure of the gas in contact with it. When the pressure remains constant, the solubility will decrease the temperature increases. 3) What are the equations for equilibrium of CO32- ion between aquatic solution and solid carbonate minerals? The equations for equilibrium of CO32- between aquatic solution and solid carbonate minerals are 2HCO3- + hv →{CH2O} + O2 + CO32- .The solubility of oxygen in water in equilibrium with atmospheric air decreases from 14.74 mg/L at 0°C to 7.03 mg/L at 35°C. 4) There are two classic methods of analytical chemistry. Name the two methods and briefly explain what they are? The two classic methods of analytical chemistry are volumetric method and gravimetric method. Volumetric method (Titrations) is using simple and inexpensive apparatus as well as rapid and accurate. Gravimetric method is the measurement of the mass of the analyte (substance / chemical that is of interest in the analytical test) 5) There are three instrumental methods of analytical chemistry. Name the three methods. For each one of the method you have written down, further explain two different examples you have learnt in each method. The first method is spectrophotometric Method.

The example is absorption spectrophotometry which is the absorption of monochromatic light by a cloud of atoms of the analyte metal (for flame operating analysis: temperature is around 3200K). Another example is Atomic emission technique which is used to measure the spectral lines emitted when the sample is heated to a very high temperature (around 7000K). The second method is...
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