Formula mass defined

Molarity (M) A concentration unit defined to be the number of moles of solute per liter of solution, 95q, 259 concentration unit conversion, 261-262 potassium chromate, 263 Mole A collection of6.0122 X 1023 items. The mass in grams of one mole of a substance is numerically equal to its formula mass, 55. See also Amount Mole fraction (X) A concentration unit defined as the number of moles of a component divided by the total number of moles, 116-117,261 Mole-gram conversions, 55-56,68-68q... 

When referring to the enormous numbers of molecules or ions that take part in a visible chemical reaction, it s convenient to use a special unit called a mole, abbreviated mol. One mole of any substance is the amount whose mass—its molar mass—is equal to the molecular or formula mass of the substance in grams. One mole of ethylene has a mass of 28.0 g, one mole of HC1 has a mass of 36.5 g, one mole of NaCl has a mass of 58.5 g, and so on. (To be more precise, one mole is formally defined as the amount of a substance that contains the same number of molecules or formula units as there are atoms in exactly 12 g of carbon-12.)... 

The formula mass of a substance is equal to its number of grams per mole. Avogadro s number is the number of atomic mass units in 1 g. It is defined in that manner so that the atomic mass of an element (in amu) is... 

Define or identify each of the following molecule, ion, formula unit, formula mass, mole, molecular mass, Avogadro s number, percent, empirical formula, molecular formula, molar mass, empirical formula mass, molecular weight. 

Formality, F The number of formula masses of solute contained in each liter of solution synonymous with analytical molarity. Formal potential, The electrode potential for a couple when the analytical concentrations of all participants are unity and the concentrations of other species in the solution are defined. Formula weight The summation of atomic masses in the chemical formula of a substance synonymous with gram formula weight and molar ma.ss. 

The formula mass of a substance is equal to its number of grams per mole. Avogadro s number is the number of atomic mass units in one g. It is defined in that manner so that the atomic mass of an element (in amu) is numerically equal to the number of grams of the element per mole. We use the term molar mass for the mass of one mol of any substance. The units are typically grams per mole. For example, the mass of 1.00 mol K is 39.1 g. 

The subscripts in the formula of a compound give the ratio of the number of atoms of each element to the number of atoms of each other element in the formula. The collection of atoms written to represent the compound is defined as one formula imit. That is, the formula unit of ammonium sulfide, (NH4)2S, contains two atoms of nitrogen, eight atoms of hydrogen, and one atom of sulfur. The term formula mass (sometimes called formula weight) refers to the sum of the atomic masses of every atom (not merely every element) in a formula unit. There are several names for formula masses corresponding to different kinds of formulas. For uncombined atoms, the formula mass is the atomic mass. For covalent compounds, which consist of molecules, the formula mass can be called the molecular mass. For ionic compounds, there is no special name for formula mass. These terms are summarized in Table 4-1. 

Atoms, most molecules, and formula units of ionic compounds are extremely tiny. Their formula masses are measured in atomic mass units, which are useful for comparison purposes only, in order to get weighable quantities of matter, a huge collection of formula units is required. The mole is defined as the number of atoms in exactly 12 grams of A millimole is 0.001 mol, and is useful for calculations with small quantities of substances. The mole is abbreviated mol, not m or M, which are used for related quantities, and millimole is abbreviated mmol. 

Define (a) molecular mass (formula mass when the formula unit is a molecule), (b) mole, and (c) molar mass. 

The Explosives Weight Parameter. Based on common knowledge about scaling of explosion effects, it seemed obvious that the nondimensional explosives weight parameter/ is proportional to the cube root of the explosives weight. The explosives weight in this formula is defined as the total amount of explosives reacting within a short time, expressed in an equivalent mass of the explosive TNT. This quantity is often also described as NEQ (net explosives quantity). 

Define the following terms (a) formula weight (or formula mass) (b) molecular weight (or molecular mass) ... 

It is all very well to calculate the atomic, molecular, and formula masses of atoms, molecules, and other compounds, but since we cannot weigh an individual particle, these masses have a limited usefulness. To make measurements of mass useful, we must express chemical quantities at the macroscopic level. The bridge between the particulate and the macroscopic levels is molar mass, the mass in grams of one mole of a substance. The units of molar mass follow from its definition grams per mole (g/mol). Mathematically, the defining equation of molar mass is... 

In what units are atomic, molecular, and formula mass expressed Define those units. 

In Chapter 2, we defined the average mass of an atom of an element as its atomic mass. Similarly, we now define the average mass of a molecule (or a formula unit) of a compound as its formula mass. (The terms molecular mass or molecular weight are synonymous with formula mass and are also common.) For any compound, the formula mass is the sum of the atomic masses of all the atoms in its chemical formula. 

To use the formula in Equation 38.2, it is necessary to define at what stage the two peaks representing the two masses are actually separate (Figure 38.4). The depth of the valley between the two peaks serves this purpose, with valley definitions of 5, 10, or 50%. A 5% valley definition is a much stricter criterion of separation efficiency than the 50% definition. 

Because variations in accurate isotope ratio measurements typically concern only a few parts per 1000 by mass and there are no universal absolute ratios, it is necessary to define some standards. For this purpose, samples of standard substances are produced and made available at two major centers IAEA (International Atomic Energy Authority, U.K.) and NIST (National Institute for Standards and Technology, U.S.). Standards from other sources are also available. These primary standards can be used as such, or alternative standards can be employed if the primary ones are not available. However, any alternative standards need to be related accurately to the primary ones (see formulae below). For example, the material PDB (PeeDee belemnite), used particularly as a standard for the ratio of isotopes, is no longer readily available, and a new standard, VPDB,... 

A common process task involves heating a slurry by pumping it through a well-stirred tank. It is useful to know the temperature profile of the slurry in the agitated vessel. This information can be used to optimize the heat transfer process by performing simple sensitivity studies with the formulas presented below. Defining the inlet temperature of the slurry as T, and the temperature of the outer surface of the steam coil as U then by a macroscopic mass and energy balance for the system, a simplified calculation method is developed. 

Which one of the following could possibly be defined as the ratio of moles of each of the given elements to moles of each of the others (a) Empirical formula, (b) molecular formula, or (c) percent composition by mass. 

The equivalent is defined in terms of a chemical reaction. It is defined in one of two different ways, depending on whether an oxidation-reduction reaction or an acid-base reaction is under discussion. For an oxidation-reduction reaction, an equivalent is the quantity of a substance that will react with or yield 1 mol of electrons. For an acid-base reaction, an equivalent is the quantity of a substance that will react with or yield 1 mol of hydrogen ions or hydroxide ions. Note that the equivalent is defined in terms of a reaction, not merely in terms of a formula. Thus, the same mass of the same compound undergoing different reactions can correspond to different numbers of equivalents. The ability to determine the number of equivalents per mole is the key to calculations in this chapter. 

The procedure can be simplified by defining a gas expansion factor Yg. For ideal gas flow the mass flow for both sonic and nonsonic conditions is represented by the Darcy formula 11... 

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