Example: What is the molecular formula of a 32 carbon alkyne? For example, an alkane with 2(n) carbon atoms, will have 6 (2n+2) hydrogen atoms. 2.General formula for alkanes is CnH2n+2; general formula for alkenes in the case of a non-cyclic compound is CnH2n while the general formula for alkynes in the case of a non-cyclic compound is CnH2n-2. Classify each compound as saturated or unsaturated. Naming Alkanes / Alkenes / Alkynes 3. (b) Classify the following compounds as alkanes, alkenes and alkynes: C 2 H 4 , C 3 H 4 , C 4 H 8 , C 5 H 12 , C 5 H 8 , C 3 H 8 , C 6 H 6. Using this formula, we can write a molecular formula for any alkane with a given number of carbon atoms. 2. Other alkenes are formed in similar way. Hydrocarbons having at least one triple bond between two carbon atoms are known as alkyne. Briefly identify the important distinctions between an alkene and an alkane. They are more reactive than alkanes and alkynes due to the presence of two π bonds. The most common alkyne is ethyne, better known as acetylene. The general chemical formula of alkanes … (a) Give the general formula of an: (i) alkane, (ii) alkene and (iii) alkyne. General formula: C n H 2n+2 . 1. In general, alkynes are more acidic than alkenes and alkanes, and the boiling point of alkynes also tends to be slightly higher than alkenes and alkanes. Alkenes form a homologous series, hence, the general formula of an alkene is stated as C n H 2n. Alkanes have the general formula C n H 2n+2 and can be subdivided into the following three groups: the linear straight-chain alkanes, branched alkanes and cycloalkanes. The generic formula for alkanes is C n H 2n + 2, where n is the number identified by the prefix. Alkanes have the general formula C n H 2n+2. Similarly; Ethane – ane + yne = Ethyne Propane – ane + yne = Propyne Butane – ane + yne = Butyne Pentane – ane + yne = Pentyne. The simplest alkene which has one double bond in its structure is ethene, C 2 H 4. You can use these generic formulas to predict the formula for any alkane, alkene, or alkyne. CH. 3. CH. Identify each as an alkane, an alkene, or an alkyne. Alkenes have at least one double bond and alkynes have at least one triple bond. Answers. Alkenes have the formula C n H 2n and alkynes use the formula C n H 2n-2. Solution: •Generic formula is C n H 2n-2 •# of C’s = n = 32 •# of H’s = 2n – 2 = 2(32) – 2 = 62 •Formula is C 32 H 62. 2. The Alkane family. Alkanes. For example, an alkane with eight carbon atoms has the molecular formula C 8 H (2 × 8) + 2 = C 8 H 18. Alkyne. C≡CCH. 3. 3.Alkanes are the most stable hydrocarbons as the carbon bonds are difficult to break. (Alkane – ane + yne = Alkyne). In the presence of a catalyst—typically platinum, palladium, nickel, or rhodium—hydrogen can be added across a triple or a double bond to take an alkyne to an alkene or an alkene to an alkane. 2. Unsaturated hydrocarbons have double or triple bonds and are quite reactive; Alkanes are the simplest family of hydrocarbons - compounds containing carbon and hydrogen only. 3. 1. Molecular Formulas. (Image to be added soon) There are various methods to prepare an alkene. Alkenes have important industrial uses, and also play an important role in our everyday lives. They undergo addition and oxidation reactions readily. Alkane is an acyclic saturated hydrocarbon consisting of hydrogen and carbon atoms (saturated because they have single bond), which are arranged in a tree structure in which all the carbon–carbon bonds are single.