Chemical calculations moles

The resultant corrections to the SCF picture are therefore quite large when measured in kcal/mole. For example, the differences AE between the true (state-of-the-art quantum chemical calculation) energies of interaction among the four electrons in Be and the SCF mean-field estimates of these interactions are given in the table shown below in eV (recall that 1 eV = 23.06 kcal/mole). 

Motes occupy the centrai position of this flowchart because the mote is the unit that chemists use in almost all chemical calculations. When you set out to solve a chemical problem, first interpret the question on the atomic/molecular level. The second part of chemical problem solving often involves quantitative calculations, which usually require working with moles. 

For work in the laboratory, it s necessary to weigh reactants rather than just know numbers of moles. Thus, it s necessary to convert between numbers of moles and numbers of grams by using molar mass as the conversion factor. The molar mass of any substance is the amount in grams numerically equal to the substance s molecular or formula mass. Carrying out chemical calculations using these relationships is called stoichiometry. 

How do we use the mole in chemical calculations Recall that Avogadro s number is defined as the number of atoms in exactly 12 grams of 12C. Thus 12 grams of 12C contains 6.022 X 1023 atoms. Also, a 12.01-gram sample of natural carbon contains 6.022 X 1023 atoms (a mixture of 12C, 13C, and 14C atoms, with an average mass of 12.01). Since the ratio of the masses of the samples (12 g/12.01 g) is the same as the ratio of the masses of the individual components (12 amu/12.01 amu), the two samples contain the same number of components. 

To perform chemical calculations, you must understand what the mole means and how to determine the number of moles in a given mass of a substance. These procedures are illustrated in Example 3.3. 

Second, quantum chemical calculations of the potential energy surface of the Cu-SMet bond shows that it costs less than 10 kJ/mole to change the Cu-Smci bond length by 100 pm around its optimum value (see Figure 10), a range larger than the natural variation in this bond [14,54]. Thus, even if the proteins could constrain this bond, it would affect the electronic part of the reduction potential by less than 10 kJ/mole, or 100 mV, i.e. much less than the variation found among the blue copper proteins. Moreover, a constrained Cu(I)-SMet bond would... 

The mole fraction of a compound is important in certain physical chemical calculations, but is not often used in biochemistry. 

In some chemical calculations, you may need to convert from moles of a compound to moles of individual atoms in the compound or from moles of individual atoms in a compound to moles of the compound. The following conversion factors can be written for use in these calculations for the molecule freon. 

The mole is a central concept in making chemical calculations. 

Nearly all calculations in chemistry are based on the mole and after you understand what this term means, you ll be well on your way to success in solving many kinds of chemical calculations. 

The term molar mass is used all the time in chemical calculations, so you need to know what it means. First, it is a mass, so it has units of mass, commonly the gram. Second, it concerns the mole (Avogadro s number). Whether you re dealing with elements or compounds, the molar... 

By definition, the atomic mass of the carbon-12 atom is exactly 12.00 amu. One mole of carbon-12 atoms has a mass of exactly 12.00 g, and that 12.00 g mass contains exactly 6.022 x 1023 carbon-12 atoms. This statement sets the benchmark for all chemical calculations involving the mole. One mole of any element is an amount of that element equal to its atomic mass in grams (its molar mass), and that mass contains 6.022 x 1023 atoms of that element. Using atomic masses, you can apply these relationships to the elements hydrogen and nitrogen. 

Interconversion between numbers of moles, particles, and grams. The mole concept is central to chemical calculations involving measured quantities of matter. 

How do we use the mole in chemical calculations Recall that Avogadro s number is defined such that a sample of any element that weighs a number of grams equal to the average atomic mass of that element contains 6.022 x 10 atoms (1 mol) of that element. For example ... 

Previously, we saw how to use the balanced equation for a reaction to calculate the numbers of moles of reactants and products for a particular case. However, moles represent numbers of molecules, and we cannot count molecules directly. In chemistry we count by weighing. Therefore, we need to review the procedures for converting between moles and masses and see how these procedures are applied to chemical calculations. 

We need to determine the mole fractions of each component in order to determine their partial pressures. To calculate mole fraction, write the balanced chemical equation to determine the correct mole ratio. 

Describes how to perform chemical calculations, involving masses and gas volumes using moles... 

For systems in which the homoallylic double bond is located unsymmetrically relative to the leaving group, like in 2-substituted norbomenes there is a comparatively small rate increase. At the same time in 7-anti-substituted norbomenes where a symmetrical position of the double bond contributes to intermediate formation of the 7-anti-norbornenyl (bishomocyclopropenyl) ion 19 the it-participation is strong Such an ion, according to quantum chemical calculations, is by 4 kcal/mole more stable than the 2-norbornenyl ion 171... 

According to the authors of Ref. in passing from the gas phase to the solution the rates of degenerate 1,2-hydride shifts in ethyl and cyclohexadienyl ions should decrease due to more effective solvation of the carbocation in the ground state, see also Ref. cf., however. Ref. This conclusion agrees with the results of quantum chemical calculations. The experimental data available, however, are either insufficient for verifying this conclusion or contradict it. For example, for the 1,2-hydride shifts in the ethyl cation only the upper limits of the activation barrier are known g 1.9kcal/mole for the solution in SbF,—SO (cf. Ref. >)... 

Chemical calculations are easiest if one starts with the appropriate chemical equation. The most important aspect in specifying the reaction is not the weight of the reactants or products but the number of (real or hypothetical) molecules taking part. To make the conversion from equations to weights a imit called the mole is utilised. 

How do we use the mole in chemical calculations Recall that Avogadro s number is defined such that a 12.01-g sample of carbon contains... 

To do chemical calculations, you mzrst understand what the mole means and how to determine the number of moles in a given mass of a substance. However, before we do any calculations, let s be sure that the process of counting by weighing is clear. Consider the following "bag" of H atoms (symbolized by dots), which contains 1 mole (6.022 x 10 ) of H atoms and has a mass of 1.008 g. Assume the bag itself has no mass. 

Information Given by Chemical Equations Mole-Mole Relationships Mass Calculations The Concept of Limiting Reactants... 

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