Heat capacity of the calorimeter

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... 

Knowing the heat capacity of the calorimeter, the heat flow for any reaction taking place within the calorimeter can be calculated (Example 8.3). 

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 ... 

A calorimeter was calibrated with an electric heater, which supplied 22.5 kj of energy to the calorimeter and increased the temperature of the calorimeter and its water bath from 22.45°C to 23.97°C. What is the heat capacity of the calorimeter ... 

We can determine calorimeter front its temperature change using Equation, which is similar to Equation calorimeter cal Here, is the total heat capacity of the calorimeter. That is, Ccal is the amount of heat required to raise the temperature of the entire calorimeter (water bath, container, and thermometer) by 1 °C. 

C06-0015. When 10.00 mL of 1.00 M HCl solution is mixed with 115 mL of 0.100 M NaOH solution in a constant-pressure calorimeter, the temperature rises from 22.45 °C to 23.25 °C. Assuming that the heat capacity of the calorimeter is the same as that of 125 g of water, calculate q for this reaction. 

C06-0017.A coffee-cup calorimeter is calibrated using a small electrical heater. The addition of 3.45 kJ of electrical energy raises the calorimeter temperature from 21.65 °C to 28.25 °C. Calculate the heat capacity of the calorimeter. 

The value of the time constant depends upon the calorimeter itself p and upon the heat capacity of the calorimeter cell and of its contents p. Typical, but necessarily approximate, values of the time constant for some heat-flow microcalorimeters are given in Table II. 

It must be noted that the heat capacity of the calorimeter cell and of its contents p, which appears in the second term of Tian s equation [Eq. (12)], disappears from the final expression giving the total heat [Eq. (19)]. This simply means that all the heat produced in the calorimeter cell must eventually be evacuated to the heat sink, whatever the heat capacity of the inner cell may be. Changes of the heat capacity of the inner cell or of its contents influence the shape of the thermogram but not the area limited by the thermogram. It is for this reason that heat-flow microcalorimeters, with a high sensitivity, are particularly convenient for investigating adsorption processes at the surface of poor heat-conducting solids similar in this respect to most industrial catalysts. 

It should be recalled, at this point, that the value of the time constant is related to the heat capacity of the calorimeter cell and of its contents [Eq. (15)]. For meaningful results, it is therefore essential that the arrangement of the inner cell remain identical for both the Joule heating and the thermal phenomenon under investigation. Strictly speaking, the time constant would be unchanged if it were possible to keep the thermal paths completely identical in both cases. This condition is, of course, very difficult to meet. 

Find the heat capacity of the calorimeter (calorimeter constant). 

Yes, the identification of the metal was different. When the heat capacity of the calorimeter is taken into account, the specific heat of the metal is 0.26 J/g-°C and the metal is identified as molybdenum, Mo (specific... 

To determine the heat capacity of the calorimeter, recognize that the heat evolved by the reaction is the negative of the heat of combustion. 

The overall heat capacity of the calorimeter is a simple function of the amount of steel the bomb comprises and the amount of water surrounding it. If the mass is m and the heat capacity is C, then the overall heat capacity is expressed by... 

Some of the heat transferred to the surroundings during an exothermic reaction are absorbed by the calorimeter and its parts. In order to account for this heat, a calorimeter constant or heat capacity of the calorimeter is required and usually expressed in J °C 1. 

Scenario A student constructed a coffee cup calorimeter (see Figure 1). To determine the heat capacity of the calorimeter, the student placed 50.0 mL of room temperature distilled water in the calorimeter. A calibrated temperature probe recorded the temperature as 23.0°C. The student then added 50.0 mL of warm distilled water (61.0°C) to the calorimeter and recorded the temperature every 30 seconds for the next three minutes. The calorimeter was then emptied and dried. Next, the student measured the temperature change when 50.0 mL of... 

We ignited a 1.5886 g sample of glucose (C6H1206) in a bomb calorimeter. The temperature increased by 3.682°C. The heat capacity of the calorimeter was 3.562 kJ/°C, and the calorimeter contained 1.000 kg of water. Find the molar heat of reaction (J/mol of glucose) for the reaction ... 

In solving problems of this type, you must realize that the oxidation of the glucose released energy in the form of heat and that some of the heat was absorbed by the water and the remainder by the calorimeter. You can use both the heat capacity of the calorimeter and the mass and specific heat of the water with the temperature change to calculate the heat absorbed by the calorimeter and water ... 

Some problems use the total heat capacity of the calorimeter (calorimeter + water). This means that the summation has already been done for you, so that you do not need to do the summation a second time. 

After the temperature change is calculated, there are several ways to proceed. If the calorimeter contains water, the heat may be calculated by multiplying the specific heat of water by the mass of water by the temperature change. The heat capacity of the calorimeter may be calculated by dividing the heat by the temperature change. If a reaction is carried out in the same calorimeter, the heat from that reaction is the difference between the heat with and without a reaction. 

The mass, m, is the mass of the solution, because the solution absorbs the heat. When a dilute aqueous solution is used in a calorimeter, you can assume that the solution has the same density and specific heat capacity as pure water. As you saw above, you can also assume that the heat capacity of the calorimeter is negligible. In other words, you can assume that all the heat that is released or absorbed by the reaction is absorbed or released by the solution. 

When 0.5 g of benzene (CgHg) is burnt in a bomb calorimeter, the temperature of the calorimeter rises from 25 °C to 33.52 °C. If the molar heat of combustion of benzene is 1955 kJ, find the heat capacity of the calorimeter ... 

The energy required to raise the temperature of the calorimeter walls is the difference between the total energy and that required for the water—that is, 254 — 220 = 34 cal. The heat capacity of the calorimeter (calories required to raise that part of its walls in contact with the liquid by 1.0°C) is... 

The temperature in a calorimeter containing 100 g of water is 22.TC. Fifty grams of water are heated to boiling (99.1°C at this location) and quickly poured into the calorimeter. The final temperature is 44.8°C. From these data, calculate the heat capacity of the calorimeter. 

We equate the heat lost to the heat gained and solve for, the heat capacity of the calorimeter ... 

A Dewar flask (vacuum-jacketed bottle) is used as a calorimeter, and the following data are obtained. Measurements in parts (a) and (b) are made to obtain the heat capacity of the calorimeter, and parts (c) and (d) are performed on an unknown metal. 

The oxygen consumption was monitored continuously with an oxygen electrode. The temperature was monitored simultaneously with a thermocouple immersed in the solution. At the start of the reaction 96 pmol NADH was added to 29.0 ml buffer containing 02. A nearly zero-order reaction was observed with the rate of 02 consumption of 6.87 pmol/min and the rate of temperature rise of 0.01171 K/ min. The heat capacity of the calorimeter and contents was 254.6 J/ K. What is AH for the above reaction NOTE The H+ is supplied by the phosphate buffer, which has a AH of dissociation of 5.4 kj mol-1. 

If the reaction is exothermic, the energy transferred as heat to the calorimeter results in a rise in temperature, AT. The temperature increase is proportional to the energy transferred, and the constant of proportionality is called the heat capacity of the calorimeter, Qal ... 

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