Calorimeter, bomb

The most common device for measuring A (7is an adiabatic bomb calorimeter (Fig. 1.17). The process under study is initiated inside a constant-volume container, the bomb . The bomb is immersed in a stirred water bath, and the whole device is the calorimeter. The calorimeter is also immersed in an outer water bath. The water in the calorimeter and of the outer bath are both monitored and adjusted to the same temperature. This arrangement ensures that there is no net loss of heat from the calorimeter to the surroundings (the bath) and hence that the calorimeter is adiabatic. 

The change in temperature, AT, of the calorimeter is proportional to the energy that the process releases or absorbs as heat. Therefore, by measuring AT we can determine yand hence find A (7. The conversion of AT to is best 

The calorimeter constant may be measmed electrically by passing a constant cmrent, /, from a source of known potential difference, U, through a heater for a known period of time, t, for then 

If we pass a current of 10.0 A from a 12 V supplyfor 300 s, then from eqn 1.17 the energy supplied as heat is 

Alternatively, C may be determined by using a reaction of known heat output, such as the combustion of benzoic acid (QH5COOH), for which the heat output is 3227 kJ per mole of QH5COOH consumed. With C known, it is simple to interpret an observed temperature rise as a release of energy as heat. 

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Measuring the gross heating value (mass) is done in the laboratory using the ASTM D 240 procedure by combustion of the fuel sample under an oxygen atmosphere, in a bomb calorimeter surrounded by water. The thermal effects are calculated from the rise in temperature of the surrounding medium and the thermal characteristics of the apparatus. 

Combustion or bomb calorimetry is used primary to derive enthalpy of fonuation values and measurements are usually made at 298.15 K. Bomb calorimeters can be subdivided into tluee types (1) static, where the bomb or entire calorimeter (together with the bomb) remains motionless during the experiment (2) rotating-... 

For substances containing elements additional to C, H, O and N a rotating bomb calorimeter is generally used. A typical rotating bomb calorimeter system is shown in figure B 1.27.4. With tiiis calorimeter considerably more water is added to the combustion bomb and the continuous rotation of the bomb both about the cylindrical axis and end over... 

Heat of combustion Incineration with/without heat Bomb calorimeter... 

Calorific value Incineration Bomb calorimeter ASTM methods... 

Calorimetry - this is a direct method in which heating value is determined experimentally with a bomb calorimeter. Approximately 1 gram of material is burned in a sealed, submerged container. The heat of... 

Thermochemistry is concerned with the study of thermal effects associated with phase changes, formation of chemical compouncls or solutions, and chemical reactions in general. The amount of heat (Q) liberated (or absorbed) is usually measured either in a batch-type bomb calorimeter at fixed volume or in a steady-flow calorimeter at constant pressure. Under these operating conditions, Q= Q, = AU (net change in the internal energy of the system) for the bomb calorimeter, while Q Qp = AH (net change in the enthalpy of the system) for the flow calorimeter. For a pure substance. 

Bomb calorimeter. The heat flow, q, for the reaction is calculated from the temperature change multiplied by the heat capacity of the calorimeter, which is determined in a preliminary experiment... 

It is found that when 1.00 g of H2 is made to react completely with Cl2 in a bomb calorimeter, the temperature in the bomb (heat capacity = 9.33 kJ/°C) rises from 20.00°C to 29.82°C. How much heat is evolved by the reaction ... 

As noted earlier, for a reaction at constant pressure, such as that taking place in an open coffee-cup calorimeter, the heat flow is equal to the change in enthalpy. If a reaction is carried out at constant volume (as is the case in a sealed bomb calorimeter) and there is no mechanical or electrical work involved, no work is done. Under these conditions, with w = 0, the heat flow is equal to the change in energy, AE. Hence we have... 

Coffee-cup calorimeter Bomb calorimeter Standard enthalpy change First law of thermodynamics AH versus AE... 

In earlier times, ethyl ether was commonly used as an anesthetic. It is, however, highly flammable. When five milliliters of ethyl ether, C HuQC/), (d - 0.714 g/mL) is burned in a bomb calorimeter, die temperature rises from 23-5°C to 39.7°Q The calorimeter heat capacity is 10.34 k)/°C. 

Isooctane is a primary component of gasoline and gives gasoline its octane rating. Burning 1.00 mL of isooctane (d = 0.688 g/mL) releases 33.0 kj ofheat. When 10.00 mL of isooctane is burned in a bomb calorimeter, the temperature in the bomb rises from 232°C to 66.5°C. What is the heat capacity of the bomb calorimeter ... 

WEB When one mole of caffeine (CgHlaN402) is burned in air, 4.96 X 103 kj ofheat is evolved. Five grams of caffeine is burned in a bomb calorimeter. The temperature is observed to increase by 11.37°Q What is die heat capacity of the calorimeter in J/°C ... 

Isooctane, CgHlg, is a component of gasoline. When 0.500 g of isooctane is burned, 24.06 kj of heat is given off. If 10.00 mg of isooctane is burned in a bomb calorimeter (heat capacity = 5175 J/°C) initially at 23.6°C, what is the temperature of the calorimeter when reaction is complete ... 

Acetylene, C2H2, is used in welding torches. It releases a lot of energy when burned in oxygen. One gram of acetylene releases 48.2 kj. When 0.750 g of acetylene is burned in a bomb calorimeter (heat capacity = 1.117 kJ/°C), the final temperature of the bomb is 54.5°C. What is the initial temperature of the calorimeter ... 

Salicylic acid, C7H603, is one of the starting materials in the manufacture of aspirin. When 1.00 g of salicylic acid burns in a bomb calorimeter, the temperature rises from 23.11°C to 28.91°C. The temperature in the bomb calorimeter increases by 2.48°C when the calorimeter absorbs 9.37 kj. How much heat is given off when one mole of salicylic acid is burned ... 

Naphthalene, Ci0Hs, is the compound present in moth balls. When one mole of naphthalene is burned, 5.15 X 103 kj ofheat is evolved. A sample of naphthalene burned in a bomb calorimeter (heat capacity = 9832 J/°C) increases the temperature in die calorimeter from 25.1°C to 28.4°C. How many milligrams of naphthalene were burned ... 

A sample of sucrose, Ci2H22On, is contaminated by sodium chloride. When the contaminated sample is burned in a bomb calorimeter, sodium chloride does not burn. What is the percentage of sucrose in the sample if a temperature increase of 1.67°C is observed when 3.000 g of the sample is burned in the calorimeter Sucrose gives off 5.64 X 103kJ/mol when burned. Theheat capacity of the calorimeter is 22.51 kJ/°C. 

Boiling point elevation (ATb) Increase in the boiling point caused by addition of a nonvolatile solute, 269-271 Bomb calorimeter Device used to measure heat flow, in which a reaction is carried out within a sealed metal container, 202-203... 

FIGURE 6.12 A bomb calorimeter is used to measure heat transfers at constant volume. The sample in the central rigid container called the bomb is ignited electrically with a fuse wire. Once combustion has begun, energy released as heat spreads through the walls of the bomb into the water. The heat released is proportional to the temperature change of the entire assembly. 

We have seen that a constant-pressure calorimeter and a constant-volume bomb calorimeter measure changes in different state functions at constant volume, the heat transfer is interpreted as A U at constant pressure, it is interpreted as AH. However, it is sometimes necessary to convert the measured value of AU into AH. For example, it is easy to measure the heat released by the combustion of glucose in a bomb calorimeter, but to use that information in assessing energy changes in metabolism, which take place at constant pressure, we need the enthalpy of reaction. 

Identify the following systems as open, closed, or isolated (a) coffee in a very high quality thermos bottle (b) coolant in a refrigerator coil (c) a bomb calorimeter in which benzene is burned (d) gasoline burning in an automobile engine ... 

The reaction of 1.40 g of carbon monoxide with excess water vapor to produce carbon dioxide and hydrogen gases in a bomb calorimeter causes the temperature of the calorimeter assembly to rise from 22.113°C to 22.799°C. The calorimeter assembly is known to have a total heat capacity of 3.00 kJ-(°C). (a) Write a balanced equation for the reaction. 

Aniline, C6H5NH2(1), is a derivative of benzene in which a hydrogen atom has been replaced by an NH2 group, (a) Write the balanced equation for the combustion of aniline, (b) What is the mass of each product when 0.1754 g of aniline is burned in excess oxygen (c) If the bomb calorimeter in which this reaction was carried out had a volume of 355 mL, what minimum pressure of oxygen at 23°C must have been used to ensure complete combustion Assume that the volume of the aniline is negligible. 

Normally, when sulfur is oxidized, the product is S02, but S03 may also be formed. When 0.6192 g of sulfur was burned, by using ultrapure oxygen in a bomb calorimeter with a heat capacity of 5.270 kJ-(°C) 1, the temperature rose 1.140°C. Assuming that all the sulfur was consumed in the reaction, what was the ratio of sulfur dioxide to sulfur trioxide produced ... 

Bohr frequency condition, 13 Bohr radius, 23 boiling, 314 boiling point, 314 alkanes, 737 anomalous, 184 boiling point prediction, 180 boiling point trends, 183 boiling-point elevation, 332 Boltzmann, L., 276 Boltzmann formula, 276 bomb calorimeter, 224... 

A commercial instrument for constant-volume calorimetiy is called a bomb calorimeter, because the container in which the reaction occurs resembles a bomb. 

A PET oligomer isolation method has utilised chloroform extraction in a Parr bomb lined with a Teflon-TFE fluoro-carbon resin [40]. The analytics of fluoropolymer processing aids (combustion analysis, XRF, EUR, 19F NMR, OM) have recently been described [29]. Combustion analysis (Parr Oxygen Bomb Calorimeter) can be used for quantitative analysis... 

A micro-bomb calorimeter exploded when the wrong proportions of sample and oxidants were used. Instead of 4 g of peroxide and 0.2 g of nitrate for 0.2 g of the sugar sample, 0.35 g of peroxide and 2.6 g of dextrose were used. The deficiency of peroxide to absorb the decomposition gases and excess of organic matter led to a rapid rise in temperature and pressure, which burst the bomb calorimeter. 

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