Constant volume bomb calorimeter

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. 

AE = q, (valid with constant volume bomb calorimeter)... 

In a constant-volume bomb calorimeter with a heat capacity of 13.418 kJ/K, 1.17 g of naphthalene, C10H8, is burned. Fifty-two joules of energy are required to ignite the sample. If the temperature rise of the calorimeter is 3.318 K, what is the A U and AH of combustion of naphthalene What is the AHy of naphthalene (You may assume that all water is formed in the liquid phase.)... 

The heat combustion (AH) of tungsten carbide at 300 K is -285.65 kcal/mole WC, and the reaction is WC(s) + (5/2)02(g) - W03(s) + C02(g). Compute the heat for the same reaction if it takes place in a constant-volume bomb calorimeter at 300 K. Assume that the gases behave ideally and that corrections to standard states are negligible for solid species. 

Combustion of table sugar produces C02(g) and H20(/). When 1.46 g of table sugar is combusted in a constant-volume (bomb) calorimeter, 24.00 kj of heat is liberated, a. Assuming that table sugar is pure sucrose,... 

A bomb calorimeter is useful for measuring the energy released in combustion reactions. The reaction is carried out in a constant volume bomb with a high pressure of oxygen. How much heat is evolved when 54.0 g glucose (C6Hi20s) is burned according to this equation ... 

Heat Transfer at Constant Volume Bomb Calorimeters... 

Calculate the heat transfer, Q, from a bomb calorimeter (constant volume) or a steady flow calorimeter (constant pressure), Qp, from theory or experimental data. 

Heat of combustion is usually measured by placing a known mass of a compound in a steel container called a constant-volume bomb calorimeter, which is fdled with oxygen at about 30 atm of pressure. The closed bomb is immersed in a known amount of... 

FIGURE 6.6 A constant-volume bomb calorimeter. The calorimeter is filled with oxygen gas before it is placed in the bucket. 

A quantity of 1.435 g of naphthalene (CioHg), a pungent-smeUing substance used in moth repellents, was burned in a constant-volume bomb calorimeter. Consequently, the temperature of the water rose from 20.17°C to 25.84°C. If the mass of water surrounding the calorimeter was exactly 2000 g and the heat capacity of the bomb calorimeter was 1.80 kJ/°C, calculate the heat of combustion of naphthalene on a molar basis that is, find the molar heat of combustion. 

A 0.1375-g sample of solid magnesium is burned in a constant-volume bomb calorimeter that has a heat capacity of 1769 J/°C. The calorimeter contains exactly 300 g of water, and the temperature increases by 1.126°C. Calculate the heat given off by the burning Mg, in kJ/g and in kJ/mol. 

The enthalpy of combustion of benzoic acid (CgHsCOOH) is commonly used as the standard for calibrating constant-volume bomb calorimeters its... 

Understand the relation between specific heat capacity and heat transferred in both constant-pressure (coffee-cup) and constant-volume (bomb) calorimeters ( 6.3) (SPs 6.3-6.5) (EPs 6.17-6.30)... 

The heats of combustion of hydrocarbons are presently determined by using a constant volume bomb calorimeter for liquids and solids and a constant pressure flame calorimeter for gases. These measurements can be very accurate (< 1 percent), since they depend mainly on the bath temperature measurement. However, calorimetric measurements cannot be made on-line and require information about the thermal properties of the combustion products of the test sample. Tire technique reported here, on the other hand, is direct, can be performed on-line, and requires no prior knowledge about the exact composition of the test sample. (The only assumption made regarding the composition is that saturated hydrocarbons are the only combustibles present in the test samples). It thus appears that this new technique may be more useful for field operations where on-line measurements of the heats of combustion of the test gases are often needed. 

Figure 6.8 A constant-volume bomb calorimeter. The calorimeter is filled with oxygen gas before it is placed in the bucket. The sample is ignited electrically, and the heat produced by the reaction can be accurately determined by measuring the temperature increase in the known amount of surrounding water.

The enthalpy of combustion of benzoic acid (CgHsCOOH) is commonly used as the standard for calibrating constant-volume bomb calorimeters its value has been accurately determined to be —3226.7 kJ/mol. When 1.9862 g of benzoic acid are burned in a calorimeter, the tempo ature rises from 21.84°C to 25.67°C. What is the heat capacity of the bomb (Assume that the quantity of water surrounding the bomb is exactly 2000 g.)... 

When 1.034 g of naphthalene (CioHg) are burned in a constant-volume bomb calorimeter at 298 K, 41.56 kJ of heat are evolved. Calculate A and A/7 for the reaction on a molar basis. 

The heat of a reaction, such as combustion, is usually measured by placing a known mass of a compound in a steel container called a constant-volume bomb calorimeter. The calorimeter is then filled with oxygen at about 30 bar of pressure. The closed bomb is immersed in a known amount of water, as shown in Figure 7.11. The sample is ignited electrically, and the heat produced by the combustion reaction can be calculated accurately by recording the rise in temperature of the water. The heat given off by the sample is absorbed by the water and the bomb. The special design of the... 

Calorimeters measure the heat released (or absorbed) during a process either at constant pressure (coffee cup qp = AH) or at constant volume (bomb qy = AE). 

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