Basal Metabolic Rate Total amount of energy needed in 24 hours to perform body’s basic functions How to Measure BMR = 4.18 x (9.99m + 6.25h – 4.92a + s) kj M = mass in Kg H = Height in cm A = age in years S = +5 for males = -161 for females

BMR = 4.18 x (9.99m + 6.25h – 4.92a + s) kj M = mass in Kg H = Height in cm A = age in years S = +5 for males = -161 for females

Where does the energy come from? Mars Bar (average choc bar!) 1007 kj Chicken salad sandwich 1200 kj Big mac (not meal – just the burger!) 2060 kj Celery stick – 44 kj

Learning Outcomes Understand the terms saturated and unsaturated Be able to identify saturated and unsaturated from structural formulae Define the term hydrocarbon Be able to recall the definition and identify molecules Be able to name the hydrocarbon basic prefixes and recall how many carbons they refer to

Triglycerides

Saturated vs Unsaturated Fatty acids H H H

Melting and boiling points H H

Trans- Fats and cis- isomer H H

Some definitions Hydrocarbons – variety of compounds made up of hydrogen and carbon Functional group – An atom, or group of atoms, that replaces a Hydrogen in a hydrocarbon. Is usually responsible for structures and properties Isomer – Substances with the same molecular formula but different structural formula Saturated – Hydrocarbon with the maximum number of hydrogen atoms bonded to carbons (no carbon-carbon double bonds)

Naming Organic Compounds Number of Carbon Atoms in the Chain Naming prefix 1 Meth- 2 Eth- 3 Prop- 4 But- 5 Pent- 6 Hex- 7 Hept- 8 Oct-

Learning Outcomes Understand the terms saturated and unsaturated Be able to identify saturated and unsaturated from structural formulae Define the term hydrocarbon Be able to recall the definition and identify molecules Be able to name the hydrocarbon basic prefixes and recall how many carbons they refer to

Alkanes Carbon has _____ valence electrons Hydrogen has _____ valence electrons Carbon wants to make ____ bonds, to have a share in ____ electrons Hydrogen wants to make ____ bonds, to share in ____ electrons Methane (natural gas) is a hydrocarbon molecule consisting of only 1 carbon… How many hydrogen atoms? Ethane is a hydrocarbon in the same homologous series, that contains 2 carbon atoms… How many Hydrogen atoms?

Homologous Series – Series of compounds with the same general formula Homologous Series – Series of compounds with the same general formula. They have very similar physical and chemical properties.

Alkanes Homologous series with a saturated carbon chain. Carbon (4 valence electrons) wants to form 4 covelant bonds. Carbon chain of given length, then saturate with hydrogen.

Alkanes Name Carbons Hydrogens Structure

Different ways of showing structures

Properties of Alkanes Melting point and boiling point of alkanes increases as the length of the carbon chain increases. Why? Viscosity _________ as length of carbon chain increases.

Isomers In the homologous series of alkanes we can see isomerism. Isomer – Substances with the same molecular formula but different structural formula. Alkane Molecular Formula Isomers Methane CH4 Ethane C2H6 Propane C3H8 Butane C4H10 Pentane C5H12 Hexane C6H14 Heptane C7H16 Octane C8H18

Naming Isomers Find the longest carbon chain in the molecule. This will be the base of the name 2. Any extra “alkyl” groups sticking to the molecule will be included in the name based on the number of carbons it contains and which carbon it is added to.

Butane

Pentane

hexane

Alkane Molecular Formula Isomers Methane CH4 Ethane C2H6 Propane C3H8 Butane C4H10 Pentane C5H12 Hexane C6H14 Heptane C7H16 Octane C8H18

Alkenes Homologous series with an unsaturated carbon chain. Carbon (4 valence electrons) wants to form 4 covelant bonds, without enough hydrogen present, some of these bonds must be carbon- carbon double bonds. Carbon chain of given length, then add double bond, then add hydrogens.

Practical: Reactivity of alkenes and alkanes Cyclohexene and cyclohexane are poisonous, avoid contact with skin and avoid breathing fumes. Bromine Water is Corrosive, avoid contact with skin and avoid breathing fumes Hair tied back. Gloves at all times. Glasses at all times. Fume hoods - Reacting Bromine water with cyclohexane, cyclohexene, cooking oil Combustion of cyclohexane, cyclohexene As with all chemistry practicals, note down observations as you go.

Reaction with Bromine Water Combustion Reaction with Bromine Water 1. Put 5 drops of cyclohexane into an evaporating dish on a heat mat. 2. Ignite the cyclohexane and observe the flame. 3. Record observations. 4. Clean the evaporating dish with paper towel. 5. Repeat steps 1 to 4 with cyclohexene and oil. 1. Put 10 drops of cyclohexane into a labeled test tube. 2. Add 10 drops of bromine water. Stopper and shake. 4. Repeat steps 1 to 3 with cyclohexene and oil. 5. Dispose of all chemicals in the organic waste bottle, NOT DOWN THE SINK. While you wait….. Make a suitable results table to record your observations. Then, why not answer some of these questions… Molecular Formula for cyclohexane and cyclohexene? Structural formula for cyclohexene and cyclohexane? Which is unsaturated? How do we know? What products do you think there are in the combustion reaction? HINT: what is the hydrocarbon reacting with? Can you write an equation for the combustion of cyclohexane/cyclohexene? Can you write an equation for the addition of bromine?

Combustion Reaction with Bromine Cyclohexane Cyclohexene Cooking Oil

Alkenes Name Carbons Hydrogens Structure

Structural Diagrams of Alkenes

Isomers In the homologous series of alkenes we can see isomerism. For a start, the double bond can be on more than 1 carbon Alkane Molecular Formula Isomers Methene No – why not? Ethene C2H4 Propene C3H6 Butene C4H8 Pentene C5H10 Hexene C6H12 Heptene C7H14 Octene C8H16

Alkane Molecular Formula Isomers Ethene C2H4 Propene C3H6 Butene C4H8 Pentene C5H10 Hexene C6H12 Heptene C7H14 Octene C8H16

Alkanes vs Alkenes Alkanes Alkenes Alkynes Saturated Hydrocarbon Unsaturated Hydrocarbon All single bonds Some carbon-carbon double bond General formula CnH2n+2 General formula CnH2n Slightly higher mpt and bpt Slightly lower mpt and bpt Structural isomers Structural isomerism Unreactive Reactivity: Alkenes are more reactive than alkanes… but why?

Alkanes vs Alkenes - reactivity Alkanes generally unreactive Alkenes react readily with halides, alcohols, hydrogen, water (under some conditions). The electron density in the double bond means atoms, molecules etc can be added here. Alkenes and Alkanes with Bromine. Bromination (or halogen addition reaction!) can be used to determine whether a hydrocarbon is saturated or not

Alkynes Homologous series with an unsaturated carbon chain. Contains 1 (or more) carbon-carbon triple bond(s). Carbon chain of given length, then add triple bond, then add hydrogens.

Alkynes Name Carbons Hydrogens Structure

Structural Diagrams of Alkynes

Isomers In the homologous series of alkenes we can see isomerism. For a start, the double bond can be on more than 1 carbon Alkane Molecular Formula Isomers Methyne No – why not? Ethyne C2H2 Propyne C3H4 Butyne C4H6 Pentyne C5H8 Hexyne C6H10 Heptyne C7H12 Octyne C8H14

Alkane Molecular Formula Isomers Ethyne C2H2 Propyne C3H4 Butyne C4H6 Pentyne C5H8 Hexyne C6H10 Heptyne C7H12 Octyne C8H14