Substances chemical formulas

Substance Chemical formula composition Gas concentration c (% (v/v)) MESG mm... 

Substance Chemical formula Molecular weight g/mole Density ratio1 (gaseous state) air = 1... 

Substance Chemical formula Molecular Density ratio12... 

Number i Substance Chemical formula Molecular mass Mi Heat capacity Cp in J/(kg K)... 

This is a colorless crystalline substance (chemical formula NajBjO,. 10 HjO) found in major quantity in the salt deposits of California, Chile, Tibet, Pern, and Canada. Sodium borate wtis once extensively used as a chemical food preservative, but in many countries, including the United States, its use for this purpose was discarded when it was shown to be potentially toxic in the amounts used. 

Mannitol and sorbitol are isomers, substances with the same chemical formula but a different shape. 

Now there are four H atoms, two Na atoms, and two O atoms on each side, and the equation conforms to the law of conservation of mass. The number multiplying an entire chemical formula in a chemical equation (for example, the 2 multiplying H20) is called the stoichiometric coefficient of the substance. A coefficient of 1 (as for H2) is not written explicitly. 

In other words, the stoichiometric coefficients multiplying the chemical formulas in any balanced chemical equation tell us the relative number of moles of each substance that reacts or is produced in the reaction. 

An equation must never be balanced by changing the subscripts in the chemical formulas. That change would imply that different substances were taking part in the reaction. For example, changing H20 to H202 in the skeletal equation and writing... 

In a balanced chemical equation (commonly called a chemical equation ), the same number of atoms of each element appears on both sides of the equation, chemical equilibrium A dynamic equilibrium between reactants and products in a chemical reaction, chemical formula A collection of chemical symbols and subscripts that shows the composition of a substance. See also condensed structural formula empirical formula,- molecular formula structural formula. 

Collective Index Subject General Subject Chemical Substance Author Formula Patents... 

Students can explain hydrogen bondings correctly, but have difficulties, to predict them from chemical formula and to draw conclusions concerning the physical properties of the substance. (Peterson et al., 1989 Ozmen, 2004)... 

The chemical formula for water shows how formulas are constructed. The formula lists the symbols of all elements found in the compound, in this case H (hydrogen) and O (oxygen). A subscript number after an element s symbol denotes how many atoms of that element are present in the molecule. The subscript 2 in the formula for water indicates that each molecule contains two hydrogen atoms. No subscript is used when only one atom is present, as is the case for the oxygen atom in a water molecule. Atoms are indivisible, so molecules always contain whole numbers of atoms. Consequently, the subscripts in chemical formulas of molecular substances are always integers. We explore chemical formulas in greater detail in Chapter 3. 

A chemical formula describes the composition of a substance by giving the relative numbers of atoms of each element. When a substance contains discrete molecules, a chemical formula is also a molecular formula. A chemical formula contains elemental symbols to represent atoms and subscripted numbers to indicate the number of atoms of each type. The simplest chemical formulas describe pure elements. The chemical formulas of most elements are their elemental symbols helium is He, silicon is Si, copper is Cu. However, seven elements occur naturally as diatomic molecules (Figure 3-lT so their chemical formulas take the form X2 A few other elements occur as atomic clusters, notably P4 and Sg. ... 

A chemical compound is a substance that contains a combination of atoms of different elements. Because a compound contains more than one element, there is more than one way to write its formula. For example, hydrogen chloride is a diatomic molecule with one atom each of hydrogen and chlorine. Its chemical formula might be written as HCl or CIH. To avoid possible confusion, chemists have standardized the writing of chemical formulas. 

Quite often, molecules have the same chemical formula but differ in their structures. For example, two compounds have the chemical formula C2 Hg O (Figure 3-2b and c). Dimethyl ether has a C—O—C linkage, while ethanol contains C—O—H. To distinguish between these two different substances, chemists write the formula of dimethyl ether as CH3 OCH3 and the formula of ethanol as CH3 CH2 OH. The first formula indicates that the molecule has two CH3 units linked to an oxygen atom. The second formula tells us that there is a C2 H5 unit attached to an OH group. Molecules that have the same molecular formula but different arrangements of atoms are called isomers. 

To check that the line structures represent the correct substances, count the number of intersections and line ends, which should equal the number of C atoms in the compound. The first line structure has five, the second has three, and the third has five, matching the chemical formulas. 

C03-0004. Write the chemical formula for each of the following substances (a) stearic acid, whose molecules contain 36 hydrogen atoms, 18 carbon atoms, and 2 oxygen atoms (b) silicon tetrachloride, whose molecules contain one silicon atom and four chlorine atoms and (c) Freon-113, whose molecules contain three atoms each of fluorine and chlorine and two atoms of carbon. 

To determine the molar mass of a substance, we need its chemical formula and elemental molar masses. From the chemical formula, determine the number of moles of each element contained in one mole of the substance. Multiply each elemental molar mass by the number of moles of that element, and add. 

The chemical formula of a compound contains essential information about its composition. The formula identifies which elements are present, and it states the number of atoms of each kind present in one unit of the compound. We need the chemical formula of a substance to calculate its molar mass. In fact, almost all chemical calculations require the correct chemical formula. How are chemical formulas determined in the first place ... 

Sometimes chemists have to analyze substances about which they know very little. A chemist may isolate an interesting molecule from a natural source, such as a plant or an insect. Under these conditions the chemical formula must be deduced from mass percentage data, without the help of an expected formula. A four-step procedure accomplishes this by using mass-mole conversions, the molar masses of the elements, and the fact that a chemical formula must contain integral numbers of atoms of each element. 

As with all calculations of chemical amounts, we must work with moles. Because grams are asked for, we must do a mole-mass conversion this requires the molar mass of the substance, which in turn requires that we know the chemical formula. 

The cations Mg and Ca are major components of bones. Calcium occurs as hydroxyapatite, a complicated substance whose chemical formula is Cas (P04)3 (OH). The structural form of magnesium in bones is not fully understood. In addition to being essential ingredients of bone, these two cations also play key roles in various biochemical reactions, including photosynthesis, the transmission of nerve impulses, and the formation of blood clots. 

Determine the chemical formulas and Lewis structures of these two substances. Describe then-bonding completely, including the geometry and hybridization for each carbon atom. 

Learning to recognize the properties of a substance by examining a chemical formula is an important part of mastering chemistry. Fortunately, common acids and bases fall into a small number of structural categories. In this section we describe how to recognize acids and bases, hi Section 17-1 we explain how chemical structure influences acidity. 

TABLE 7 Common Substances and Their Chemical Formulas... 

Thus, three types of components can be distinguished in most substances, whether of natural origin or made by humans major, minor, and trace components (see Table 8). The major components, also known as the main or matrix components, are those that determine the chemical nature and properties of a substance. The major components occur in the substance in high concentration, generally exceeding 1 % of the total weight. In minerals and biological substances, for example, the major components are those that appear in the chemical formula that expresses their composition. 

The carbohydrates are substances made by green plants from carbon dioxide that they extract from the air and from water absorbed from the soil. The term carbohydrate is derived from the chemical formulas of the compounds, which can be written so as to express their composition in terms of atoms of carbon combined with molecules of water the formula for sucrose (table sugar), for example, is C12H22011f but it can also be written as C12(H20)ll, indicating that the molecule consists of 11 molecules of water... 

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