Joules conversion factors

Table 1-7 provides a number of useful conversion factors. To make a conversion of an element in U.S. customary units to SI units, one multiplies the value of the U.S. customary unit, found on the left side in the table, by the equivalent value on the right side. For example, to convert 10 British thermal units to joules, one multiplies 10 by 1054.4 to obtain 10544 joules. 

Your electric bill deals with a different unit of electrical energy called the kilowatt hour (kWh). The joule and the kilowatt hour are related through a simple conversion factor ... 

This equation can be used to calculate the energy change in joules, if you know Am in kilograms. Ordinarily, Am is expressed in grams AE is calculated in kilojoules. The relationship between AE and Am in these units can be found by using conversion factors ... 

Due to a fortuitous cancellation of units, volume can be expressed in cm3 and pressure in MPa to give the same results as volume in m3 with pressure in Pa, without invoking any conversion factors. Thus pV in Pa m3 gives Joules as does pV in MPa cm3. 

The only quantity considered here is the enthalpy of formation, A fH°, at 298.15 K. Data are given in units of kJmol-1. The conversion factor 1 thermochemical calorie = 4.1840 joules was used. 

Therefore, if we work in pascals and cubic meters, the work is obtained in joules. However, we might have expressed the pressure in atmospheres and the volume in liters. In this case, we may need to convert the answer (in liter-atmospheres) into joules. The conversion factor is obtained by noting that 1 L = 10 3 m3 and 1 atm = 101 325 Pa exactly therefore... 

The use of non-SI units is strongly discouraged. For these units there often do not exist standards, and for historical reasons the same denomination may mean sundry units. For example, it is common practice in theoretical chemistry to state energy values in kilocalories. However, to convert a calorie to the SI unit Joule, there exist different conversion factors ... 

Calculate the conversion factor for changing liter atmosphere to (a) erg, (b) joule, and (c) calorie. Calculate the conversion factor for changing atmosphere to pascal and atmosphere to bar. 

For chemical reactions and phase transformations, the energy absorbed or liberated is measured as heat. The principal unit for reporting heat is the calorie, which is defined as the energy needed to raise the temperature of 1 gram of water at l4.5° C by a single degree. The term kilocalorie refers to 1,000 calories. Another unit of energy is the joule (rhymes with school), which is equal to 0.239 calories. Conversely, a calorie is 4.184 joules. The translation of calories to joules, or kilocalories to kilojoules, is so common in chemical calculations that you should memorize the conversion factors. 

Although SI is the internationally accepted system of measurement in science, other units are encountered. Useful conversion factors are found in Table 1-4. For example, common non-SI units for energy are the calorie (cal) and the Calorie (with a capital C, which stands for 1 000 calories, or 1 kcal). Table 1-4 states that 1 cal is exactly 4.184 J (joules). 

Multiply by the conversion factor to arrive at the answer 1 joule... 

Other units are more convenient when we are dealing with individual photon energies. It is common to use the electron volt (eV), equal to the kinetic energy imparted to an electron when it is accelerated in a potential of 1 V. The conversion factor between electron volts and joules is numerically equal to the charge on an electron ... 

The requirements set out in this publication and taken mainly from the report on the Nutrient Requirements of Poultry (NRC, 1994) are based on ME (AME), expressed as kilocalories (kcal) or megacalories (Meal)/kg feed. This energy system is used widely in North America and in many other countries. Energy units used in some countries are based on joules (J), kilojoules (kj) or megajoules (MJ). A conversion factor can be used to convert calories to joules, i.e. IMeal = 4.184 MJ 1MJ = 0.239 Meal and 1MJ = 239 kcal. Therefore, the tables of feedstuff composition in this publication show ME values expressed as MJ or kj as well as keal/kg. 

An important physical quantity s value is 8.314 joules or 0.08206 liter atmosphere. What is the conversion factor from joules to liter atmospheres ... 

There is an increasing use of joules as a measure of energy in this case the conversion factors are ... 

It is clear that with the definition of the Ampere also the other electrical quantities are defined. Thermodynamics required the introduction of the base quantities temperature and amount of substance, with the Kelvin and the mol as units. The unit of energy is the Joule, so that no conversion factor is involved here either. 

CGS units have been used in the text and not SI units, as is the current trend. One important conversion factor, which is required for linking SI and CGS systems is that, one calorie equals 4.186 joules. 

Atomic units (a.u.) are obviously convenient when finding electrical properties by ab initio calculations. The conversion factor to SI units (Coulombs, meters, and joules) is... 

The heat transfer was originally measured in units of calories, where one calorie was defined as the quantity of energy required to raise one gram of pure water from 14.5 to 15.5 °C at one atmosphere. This definition has been supplanted by the introduction of the joule, which represents the energy specified by the conversion factor 1 cal = 4.184 joules. One joule is also equivalent to the energy developed in a circuit by an electric current of one ampere flowing through a resistance of one ohm (driven by a potential difference of one volt) in one second. 

When setting up your equations, use the correct conversion factors so that you get the desired units when cancehng. But be careful to keep values for vaporization together and separate from those for fusion. Keep track of your units You may have to convert from joules to kilojoules or vice versa. 

The SI unit of heat and energy is the joule (J). One joule is the equivalent of 0.2390 calories, or one calorie equals 4.184 joules. Table 16-1 shows the relationships among calories, nutritional Calories, joules, and kilojoules (kJ) and the conversion factors you can use to convert from one unit to another. 

Converting Units Table 25-2 gives Approximate Energy values in units of MeV. Convert each value into joules using the following conversion factor (1 MeV = 1.61 X 10 J). For more help, refer to Unit Conversion in the Math Handbook on page 901 of this textbook. 

Suppose a 10.00-kg mass drops through a height difference of 3.00 m, and the resulting work is used to turn a paddle in 200.0 g water, initially at 15.00°C. The final water temperature is found to be 15.35°C. Assuming that the work done is used entirely to increase the water temperature, calculate the conversion factor between joules and calories. 

The kilowatt-hour (kWh) is a common unit in measurements of the consumption of electricity. What is the conversion factor between the kilowatt-hour and the joule Express 15.3 kWh in joules. 

Thermodynamic data are given according to the Systeme International d unites (SI units). The unit of energy is the joule. Some basic conversion factors, also for non-thermodynamic units, are given in Table II-4. 

According to Equation (6.11), the units for work done by or on a gas are liters atmospheres. To express the work done in the more familiar unit of joules, we use the conversion factor... 

Convert the energy released in Example 8.2 to joules (recall the conversion factor for calories and joules. Chapter 1). 

Calculate the energy released, in joules, in Question 8.31 (recall conversion factors, Chapter 1). 

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