The Density of Carbon Dioxide

Hypothesizing Air is a mixture of mostly nitrogen and oxygen. Use observations to form a hypothesis about which has greater density, air or carbon dioxide. 

Materials masking tape, aluminum foil, metric ruler, 1-L beaker, candle, matches, thermometer, barometer or weather radio, baking soda (NaHCOj), vinegar (5% CH3COOH) 

Roll a 23-cm x 30-cm piece of aluminum foil into a cylinder that is 6 cm x 30 cm. Tape the edges with masking tape. 

Use matches to light a candle. CAUTION Run water over the extinguished match before throwing it away. Keep all hair and loose clothing away from the flame. 

Place 30 g of baking soda in the bottom of a large beaker. Add 40 mL of vinegar. 

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When arranging ventilation, remember that the density of carbon dioxide gas is greater than that of air. 

Cavendish s papers next described experiments with carbon dioxide, which he called fixed air. He studied its solubility in water and its efficacy in extinguishing flames. He concluded that when one part carbon dioxide was mixed with eight parts of ordinary air, candles would not burn. He also determined the density of carbon dioxide, finding that it was about 50 percent heavier than air. This result is astonishingly close to the modern value of 52 percent. 

A balance suitable for measuring the density of carbon dioxide and other gases is described by Edwards.18 Although excellent for ordinary work it can not attain the accuracy required here. A more sensitive gas density balance has been described by Cady19 in which a balloon is suspended from an ordinary high sensitivity... 

Both the mutual solubility of the coexisting liquid and supercritical gas phases and the density of carbon dioxide are the most important parameters in influencing interfacial tension in systems with both a non-volatile liquid and a supercritical component. 

Table 2.7 Errors in predicting the density of carbon dioxide using several...

Example 7, What is the density of carbon dioxide at standard conditions ... 

Retention is a function of pressure (actually density). However, one should expect only modest changes in retention with relatively large changes in pressure under most modes of operation. At the relatively low temperatures (30-60°C) and moderate pressures (100-200 bar outlet) that have been empirically found to give the best results for separating small druglike molecules, the density of carbon dioxide/methanol mixtures is between 0.75... 

When the carbon dioxide gas is released, the mass of the solution will decrease. If we know the starting mass of the solution and the mass of solution after the reaction is complete (given in the problem), we can calculate the mass of carbon dioxide produced. Then, using the density of carbon dioxide, we can calculate the volume of carbon dioxide released. 

One of the most important properties of an SCF is that its physical properties can vary dramatically as a result of relatively small changes in temperature and pressure. This effect is most pronounced around the critical point, where the density of carbon dioxide is approximately 0.46 g/mL. If the pressure is doubled, the density of the fluid increases dramatically, reaching a density comparable to that of liquid carbon dioxide (Figure 4.3). 

Use the Pitzer correlation with the Lee-Kesler graphs to estimate the density of carbon dioxide at 35 bar, 75 °C. Solution First we collect the critical properties of CO2 ... 

The first three plots are related to the density of carbon dioxide and the three that follow are related to the enthalpy. These do not necessarily cover the same range of temperatures and pressure as the tables do but focus in on interesting subsets. 

Given that the molar volume of liquid carbon dioxide at —37 C is 39.9 mL/mol and the molar volume of solid carbon dioxide at — 79 C is 28.2 ml. /mol, calculate the density of carbon dioxide at each set of conditions. If carbon dioxide were to act as an ideal gas, what would be its density at 5 0°C When one compares each value for density to the state of the carbon dioxide, which phase change results in the greater change in density ... 

The concentration of carbon dioxide gas in ppm can be converted to percentage biodegradation by calculating the mass of carbon produced and then dividing by the initial mass of carbon in the sample. Equation D. 1 lists the conversion factor from carbon dioxide gas concentration to grams of carbon produced. The ppm concentration is divided by 10,000 to convert the ppm to volume fraction of carbon dioxide gas. The volume fraction of carbon dioxide gas is multiplied by the liters of free air of gas and then by the density of carbon dioxide to yield the mass of carbon dioxide. The mass of carbon dioxide is multiplied by the ratio of the atomic mass of carbon and the molecular mass of carbon dioxide. 

Some physical properties of supercritical fluids are in between those of typical gases than liquids. For example, the viscosity of supercritical fluids is about an order of magnitude lower (10 vs. 10 N s/m ) and the solute diffusivity of supercritical fluids is an order of magnitude higher (10 vs. 10 cm ) than for liquid solvents (64). These properties of viscosity and solute diffusivity contribute to improved mass transfer for solutes in the supercritical state, and, therefore, speed extraction rates. The density of carbon dioxide can be increased to densities... 

Before introducing numerical values, the data, given in parts per million (ppm) (m CO2/m air) must be converted to kilogram per cubic meter (kg/m ). This is done by multiplying parts per million values by the density of carbon dioxide, 1.79 kg/m. We obtain... 

Experiment.—Determine the Density of Carbon Dioxide relative to that of Air, and calculate the Molar Waght of the Gas. 

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