formula question

[jshjnh]

I am pretty new to this and I have a question. I have C₆H₁₂O₆. how would the formula change if it was 4 carbons. I have been reading, but I am have a hard time understanding..

thanks!

[peter]

I am pretty new to this and I have a question. I have C₆H₁₂O₆. how would the formula change if it was 4 carbons. I have been reading, but I am have a hard time understanding..

thanks!

The compound that have 4 carbon atoms in the same homologous series is C₄H₈O₆
The homologous series is C(n)H(2n)O₆.

Here is a relevant article:

Homologous series

Homologous series is a series of organic compounds with a similar general formula, possessing similar chemical properties due to the presence of the same functional group, and shows a gradation in physical properties as a result of increase in molecular size and mass (see relative molecular mass). For example, ethane has a higher boiling point than methane since it has more Van der Waals forces with neighbouring molecules. This is due to the increase in the number of atoms making up the molecule. Organic compounds in the same homologous series vary by a CH₂.

Alkanes (paraffins), alkenes (olefins), Methoxyethane (ethers), and alkynes (acetylenes) form such series in which members differ in mass by 14, 12, and 10 atomic mass units, respectively. For example, the alkane homologous series begins with methane (CH₄), ethane (C₂H₆), propane (C₃H₈), butane (C₄H₁₀), and pentane (C₅H₁₂), each member differing from the previous one by a CH₂ group (or 14 atomic mass units).

Similarly, there is the alcohol homologous series that starts with methanol (CH₄O), ethanol (C₂H₆O), as primary alcohols, isopropanol (C₃H₈O) as a simple secondary alcohol, and a simple tertiary alcohol is tert-butanol (C₄H₁₀O).

Even while the general formula are the same, they have different structures that can lead the exact same compound to different properties, although they will always present the same chemical properties while as a homologous compound.

Compounds in each set have the same little group of atoms called the functional group. Most chemical properties of organic compounds are due to the presence of the functional group.

Alkanes: CnH₂n + 2 (n more than or equal to 1) CH₄, n = 1
Alkenes: CnH₂n (n more than or equal to 2) C₂H₄, n = 2
Alkynes: CnH₂n − 2 (n more than or equal to 2) C₂H₂, n = 2
Alcohols: CnH₂n + 2O (n more than or equal to 1) CH₄O, n = 1
Carboxylic acids: CnH₂nO₂ (n more than or equal to 1) CH₂O₂, n = 1
Where n represents the number of carbon atoms present.

(source: http://en.wikipedia.org/wiki/Homologous_series)