Molecular formula of butane

The empirical formula of butane, the fuel used in disposable lighters, is C2H5. In an experiment, the molar mass of butane was determined to be 58 g/mol. What is the molecular formula of butane ... 

Write the molecular formula of butane. What is the name of C10H22 ... 

Only two alkanes have the molecular formula C4H10 butane and isobutane (2-methylpropane)— both of which give two monochlorides on free-radical chlorination. However, dehydrochlorination of one of the monochlorides derived from butane yields a mixture of alkenes. 

Before we can write possible structural formulas for a compound, we need to know its molecular formula. The molecular formula simply gives the number of atoms of each element in one molecule of the compound. For example, the molecular formula for butan-l-ol is C4H10O. 

An organic compound with the molecular formula C4H10 can exist as two compounds BECAUSE n-Butane and 2-methylpropane are isomers that have the molecular formula of C4H10. 

If we examine the molecular formulas of the alkanes we have so far considered, we see that butane contains one ca th and two hydrogens more than propane. 

Many hydrocarbons exist as structural isomers, which are compounds that have the same molecular formula but different structures. For example, both butane and isobutane have the same molecular formula of C4H10 (see Problem 11.19 on p. 457). Calculate the mole percent of these molecules in an equilibrium mixture at 25°C, given that the standard free energy of formation of butane is —15.9 kJ/mol and that of isobutane is —18.0 kJ/mol. Does your result support the notion that straight-chain hydrocarbons (that is, hy-... 

As we saw earlier, there are two arrangements of the atoms represented by the molecular formula C4HJ0 butane and 2-methylpropane. Molecules having the same molecular formula but a different arrangement of atoms are called constitutional, or structural, isomers. These isomers are unique compounds because of their structural differences, and they have different physical and chemical properties. Butane... 

Hydrocarbon structures may be altered so that their physical characteristics make them more economically valuable. One such alteration is called branching, or isomers. An isomer is a hydrocarbon that has the same molecular formula, i.e., the same number of hydrogen atoms and carbons, but a different structural form. The molecular formula for butane is C4H10 the molecular formula for the isomer of butane would be t-C4Hio (Figure 4.9). The formula stays the same, but the structure... 

A four-carbon compound is named butane, with the molecular formula of 411,0. Structures, molecular formulas, and some physical characteristics of these alkane-compressed gas compounds are shown in Figure 4.8. Notice the differences in boiling points and flammable ranges. As the carbon content increases, the boiling point of the compounds increases. In addition to carbon content, polarity and branching of compounds will affect physical characteristics. This concept will be discussed in more detail in Chapter 5. For now, just be aware that there are relationships between the physical characteristics of flammable gases, which include ignition temperature, heat output, vapor content, and vapor pressure. 

Isobutane, C4H10, has the same molecular formula as butane, the straight-chain hydrocarbon. However, isobutane and butane have different structural formulas and, therefore, different molecular structures. Butane and isobutane are constitutional (or structural) isomers, compounds with the same molecular formula but different structural formulas. Figure 24.4 depicts molecular models of isobutane and butane. Because these isomers have different structures, they have different properties. For example, isobutane boils at - 12°C whereas butane boils at 0°C. Here the difference in boiling point can be attributed to the fact that isobutane has a more compact molecular structure than butane, which results in weaker intermolecular interactions between isobutane molecules. 

Methane is the only alkane of molecular formula CH4 ethane the only one that is C2H6 and propane the only one that is C3Hj Beginning with C4H10 however constitutional isomers (Section 1 8) are possible two alkanes have this particular molecular formula In one called n butane, four carbons are joined m a continuous chain The nmn butane stands for normal and means that the carbon chain is unbranched The second isomer has a branched carbon chain and is called isobutane... 

Isomers are substances having the same molecular formula and molecular weight, but differing in physical and chemical properties. Since branched and straight-chain alkanes with the same molecular formula can exist as distinct structures having different geometrical arrangement of the atoms, they are termed structural isomers. One example is C H,j (butane) which has two isomers ... 

Two different alkanes are known with the molecular formula C Hm- In one of these, called butane, the four carbon atoms are linked in a straight (unbranched) chain. In the other, called 2-methylpropane, there is a branched chain. The longest chain in the molecule contains three carbon atoms there is a CH3 branch from the central carbon atom. The geometries of these molecules are shown in Figure 22.2 (p. 581). The structures are... 

Compounds having the same molecular formula but different molecular structures are called structural isomers. Butane and 2-methylpropane are referred to as structural isomers of C4H10. They are two distinct compounds with their own characteristic physical and chemical properties. 

Isomers are distinctly different compounds, with different properties, that have the same molecular formula. In Section 22.1, we considered structural isomers of alkanes. You will recall that butane and 2-methylpropane have the same molecular formula, C4H10, but different structural formulas. In these, as in all structural isomers, the order in which the atoms are bonded to each other differs. 

The conversion of a chemical with a given molecular formula to another compound with the same molecular formula but a different molecular structure, such as from a straight-chain to a branched-chain hydrocarbon or an alicyclic to an aromatic hydrocarbon. Examples include the isomerization of ethylene oxide to acetaldehyde (both C2H40) and butane to isobutane (both C4H10). 

The molecular formulas just shown for 10 alkane hydrocarbon molecules represent the proportions of carbon to hydrogen in each molecule. These formulas do not reveal much about their structures, but rather indicate the proportions of each element in their molecules. Each molecule may have several different structures while still having the same formula. Molecules with different structures but the same formulas are called isomers. For example, n-butane is formed in a straight chain, but in an isomer of butane, the CH branches off in the middle of the straight chain. Another example is ethane, whose isomeric structure can be depicted as H,C H,C-CH,. The name for the normal structure sometimes uses n in front of the name. 

For a given molecular formula there is often more than one way of joining the atoms together, whilst still satisfying the rules of valency. Such variants are called structural isomers or constitutional isomers - compounds with the same molecular formula but with a different arrangement of atoms. A simple example is provided by C4H10, which can be accommodated either by the straight-chained butane, or by the branched-chain isobutane (2-methylpropane). 

This second branched molecule is called isobutane. Compounds sharing the same molecular formula but having different structures are called structural isomers. Normal butane and isobutane have different physical properties. The number of structural isomers for the alkanes is included in Table 15.1. It can be seen in this table that as the number of carbon atoms increases that the number of possible isomers also increases. The fact that numerous isomers exist for most organic compounds is another reason why there are so many organic compounds. 

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