Alkaloids are the most diverse group of secondary metabolites and over 5000 compounds are known.
Introduction Alkaloids are the most diverse group of secondary metabolites and over 5000 compounds are known. They are most commonly encountered in the plant kingdom, but representatives have been isolated from most other orders of organisms ranging from fungi to mammals. For years, there has been interest in their pharmacological activities, and for a long time selected plant products (containing alkaloids) have been used as poisons for hunting, murder, euthanasia, a euphoriants, psychedelics, and stimulants (e.g. morphine and cocaine) or as medicines (e.g. ephedrine). Many of our modern drugs now contain the same compound or synthetic analogues, and the pharmacological and toxicological properties of these compounds are thus of immense interest and importance. Almost two centuries have elapsed since Serturner isolated the first organic base clearly recognised as such, a crystalline substance that he obtained from the opium poppy, Papaver somniferum, and called morphine. The name alkaloid is applied to the members of a class of natural products of basic nature, and is derived from the name "vegetable alkali" first applied to these substances. They all owe their basic nature to an amino nitrogen. It is more difficult than at first might be supposed to define the term alkaloid. The work was coined in 1818 by Meissner and implies a compound similar to an alkali, referring to
Enthalpy - investigate the difference in enthalpy of combustion for a number of alcohols
Enthalpy I am going to investigate the difference in enthalpy of combustion for a number of alcohols, the enthalpy of combustion being the 'enthalpy change when one mole of any substance is completely burnt in oxygen under the stated conditions'. I will be attempting to find how the number of carbon atoms the alcohol contains effects the enthalpy change that occurs during the combustion of the alcohol. Method I plan to measure the enthalpy change by burning the alcohol, using a spirit burner, I will then use the heat produced during the combustion of the alcohol to heat 100ml of water that will be situated in a copper calorimeter directly above the burning alcohol. The calorimeter is made of copper as copper has a high thermal conduction value, this basically means that it is a good conductor of heat so a lot of the heat the copper receives will be passed on to the water which I am then able to measure. During the experiment I will be taking a number of measurements, I will firstly take the initial temperature of the water and initial mass of the alcohol I will then burn the alcohol until an increase in temperature of 20oc has occurred in the water I will then reweigh the alcohol. The measurements * Mass of alcohol burned (g) * Temperature increase (oc) will tell me what mass of alcohol is used during combustion to cause the temperature increase of 20oc in the water, I
Investigate the difference in enthalpy of combustion for a number of alcohols.
Enthalpy I am going to investigate the difference in enthalpy of combustion for a number of alcohols, the enthalpy of combustion being the 'enthalpy change when one mole of any substance is completely burnt in oxygen under the stated conditions'. I will be attempting to find how the number of carbon atoms the alcohol contains effects the enthalpy change that occurs during the combustion of the alcohol. Method I plan to measure the enthalpy change by burning the alcohol, using a spirit burner, I will then use the heat produced during the combustion of the alcohol to heat 100ml of water that will be situated in a copper calorimeter directly above the burning alcohol. The calorimeter is made of copper as copper has a high thermal conduction value, this basically means that it is a good conductor of heat so a lot of the heat the copper receives will be passed on to the water which I am then able to measure. During the experiment I will be taking a number of measurements, I will firstly take the initial temperature of the water and initial mass of the alcohol I will then burn the alcohol until an increase in temperature of 20oc has occurred in the water I will then reweigh the alcohol. The measurements [Mass of alcohol burned (g), Temperature increase (oc)] will tell me what mass of alcohol is used during combustion to cause the temperature increase of 20oc in the water, I can
COMPARING THE ENTHALPY CHANGE OF COMBUSTION OF DIFFERENT FUELS.
COMPARING THE ENTHALPY CHANGE OF COMBUSTION OF DIFFERENT ALCHOHOLS. Aim The aim of my experiment will be to find out which alcohols have a higher enthalpy change of combustion. The comparison of the enthalpy changes of these fuels will then determine the alcohol efficiency and effectiveness. I will experiment on the first 5 consecutive primary alcohols. These are; methanol, ethanol, propan-1-ol, butan-1-ol, pentan-1-ol and hexan-1-ol. The reason why I chose these fuels is because they are the most reliable and accurate fuels to compare within the group; which also have the smallest variable, 'add one carbon' each time, to the aliphatic chain. All combustion reactions are exothermic which is why I am expecting all the values for the enthalpy change of combustion to always be negative. CH3OH + 1.5O2 CO2 + 2H2O METHANOL CH3CH 2OH+ 3O2 2CO2 + 3H2O ETHANOL CH3CH 2 CH 2OH+ 4.5O2 3CO2 + 4H2O PROPAN-1-OL CH3CH 2 CH 2 CH 2OH+ 6O2 4CO2 + 5H2O BUTAN-1-OL CH3CH 2 CH 2 CH 2 CH 2OH+ 7.5O2 5CO2 + 6H2O PENTAN-1-OL CH3CH 2 CH 2 CH 2 CH 2 CH 2OH+ 9O2 6CO2 + 7H2O HEXAN-1-OL Prediction I believe that hexan-1-ol will have the highest enthalpy of
detremining the rate equation
The determination of a rate equation Aim The aim of this experiment is to plan an experimental procedure leading to a graphical method to determine how the concentration or the volume of the components affects the rate of the reaction whose equation is given below: 2HCl(aq) + Na2S2O3(aq) --> 2NaCl(aq) + SO2(g) + S(s) + H2O(l) Introduction In this experiment in order for the reaction to take place the reactant particles must collide, and only some of those colliding particles lead to a chemical change. The rate of reaction is defined as the amount of in moles of a reactant which is used up in a given time, in this case it's the amount of sulphur formed in a given time. To work out the rate equation I will conduct two methods. In order to relate the rate of reaction with the concentration of the components involved I will have to obtain results to help me determine the rate of expression of the reaction. There are two methods used to determine the rate expression. This is done by measuring the concentration over time. The concentration has to be measured throughout the reaction. From the results obtained graphs are drawn and from that the order of the reaction is determined. The reason I'm not using this method is I don't have the right equipment to do that. The concentrations will be constantly changing and therefore
To work out the enthalpy change of combustion of alcohols
Enthalpy of combustion planning Aim: To work out the enthalpy change of combustion of alcohols To work out the enthalpy change of combustion of the alcohols, the energy output must be measured. This simplest way of doing this accurately is to use the thermal energy of combustion to raise the temperature of a substance with a known specific heat capacity. The rise in temperature of this substance can then used to work out the thermal energy used to do this work. Basic plan Apparatus Metal calorimeter Thermometer measures to 0.1 oc Clamp stand Alcohol with spirit burner Heat proof mat Scales that measure to two decimal places Wooden splint 00cm3 measuring cylinder that measures 1cm3 For safety To begin with prepare a table remove all items of stationary from the surface and place them in bags, leaving only the paper and pen that are to be used to record the results. Remove bags from under the desks and place them in the designated positions. With the exception of the scales collect all the apparatus above, and place them on the prepared table. To ensure the weights recorded on the scales are reliable. Switch the scales on, wait until the balance has settled, once the balance has settled press the tare button to ensure that the balance reads 0.00 and the balance registers the entire weight of the spirit burner alcohol. Weigh the alcohol in the burner to two
analysing the unknown compound A
Introduction The aim of this coursework is to identify two unknown organic compounds which are mono-functional using wet tests we deem suitable and the spectroscopy of the unknown compounds. Background Wet Tests Reaction with bromine To test for alkenes bromine water can be used. If the unknown compound is an alkene it will decolourise the bromine water. This is because the ?-bond which makes up part of the double bond in alkenes is relatively easily to break making alkenes react in electrophilic addition reactions. Although most of this information may seem relevant to the investigation, the only important part is that bromine water can be used to test for alkenes as alkenes decolourise the bromine water. Reaction with acidified potassium dichromate Acidified potassium dichromate is an oxidising agent which can be used to test for primary and secondary alcohols. This is because primary alcohols can be oxidised into aldehydes and secondary into ketones whereas tertiary alcohols cannot be oxidised at all. "In the reaction, the orange dichromate(VI) ions are reduced to green chromium(III) ions" as said by the Essential AS Chemistry book for OCR. In addition to this because aldehydes can be further oxidised into carboxylic acids, acidified potassium dichromate can also be used distinguish aldehydes from ketones as ketones cannot be further oxidised. The most important part
Neutralization investigation
Neutralization investigation Nicky G I will conduct an investigation into the effect an alkali and an acid have on each other using titration, find out whether neutralization occurs, and what factors effect neutralization if any. I will look at how concentration and type of an acid can affect neutralization. Acids And Alkalis Acids and alkalis are substances found everywhere in our daily lives. They both have different properties that can be both harmful and advantageous. Some examples of substances containing alkaline are toothpaste, which is used to fight acid in the mouth built up by bacteria in the mouth digesting sugar, and antacids, which are tablets used to combat acid indigestion. A base is any substance that can neutralize an acid, so an alkali can be called a soluble base as it also dissolves in water. There are other known compounds that can neutralize acids such as zinc carbonate. Acidic solutions are often found in the kitchen and include cleaning products to fight lime scale build up, and stronger oven spray. All these examples of acidic and alkaline solutions are also examples of neutralization, which occurs equal in our daily lives. A neutral substance is neither an acid nor an alkali and shares no properties with them. Neutral substances such as pure water tend not to be toxic and corrosive and generally are much safer to handle than acids and alkalis.
Experiment. Is the order of reaction affected if the acid is monoprotic or diprotic?
Is the order of reaction affected if the acid is monoprotic or diprotic? Theory The collision theory In order for a chemical reaction to occur, particles must collide with each other. The particles have to collide with enough energy for bonds to be broken (needing energy) and new bonds to form (releasing energy). If the particles react with each other, the collision is said to be successful. The minimum amount of energy that is required at the beginning of a reaction to start of is called the 'activation energy' (see figure 1) (Figure 1 reference 1) Factor effecting rate of reaction Concentration If you increase the concentration of the reactants this will mean that there will be more particles available, therefore these particles will be likely to collide with each other more often, thus increasing the rate of reaction. Monoprotic acids A monoprotic acid can only donate or lose one H+ ion i.e. they only have one dissociable proton. The acid that I will be using in my investigation that is monoprotic is Hydrochloric acid. Diprotic acid A diprotic acid however has two dissociable protons. An example of this type of acid is sulphuric acid. Ka This is an acid dissociation constant which is a measure of the strength of acid in solution. - Ka equals the equilibrium concentration of the deprotonated ion A- multiplied by the equilibrium concentration of H+,
Comparing The Enthalpy Change OfCombustion Of Different Alcohols
Comparing The Enthalpy Change Of Combustion Of Different Alcohols The aim of my experiment is to investigate the enthalpy of combustion of a range of alcohols. The standard enthalpy of combustion is the enthalpy change that occurs when 1 mole of a fuel is burned completely in oxygen under standard conditions - 1 atmosphere pressure and 298K. All combustion reactions are exothermic which is why I am expecting all the values for the enthalpy change of combustion to always be negative. Prediction I predict that the greater the number of carbon atoms there are in the alcohol molecule, the greater the enthalpy change of combustion it will have. This is because in a chemical reaction energy is needed in order to break bonds and energy is released when bonds are made. If I were to look at these two values; the energy required to break the bonds of the reactants and the energy released when the bonds of the product are made then I am able to work out the enthalpy change of combustion of the alcohol. In order to do this we need to know the bong enthalpies of the bonds in the process. The quantity of energy needed to break a particular bond in a molecule is called the bond enthalpy. Below is a table containing the bond enthalpies of the bonds that occur in the combustion of an alcohol. Bonds Average bond enthalpy/kJ mol-1 C-C +347 C-H +413 C-O +358 O-H +464 O=O +498 C=O
