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Planning - Variable input - Alcohol

Extracts from this document...

Introduction

SKILL P~PLANNING Input Variables Alcohol This is the variable I am going to investigate. An increase in the length of carbon-carbon chains will result in an increase of energy given out. This is due to the longer hydrocarbons having, a greater attraction to each other. Therefore more energy is needed to break them down so more energy is given out since the reaction is exothermic. Volume of Alcohol A greater volume means more molecules of the alcohol. More molecules will mean more atoms, hence more carbon-carbon chains. As is described above more carbon-carbon chains in this experiment will mean more energy. Therefore to keep this variable constant each alcohol will have the same number of molecules. Isomers of Alcohol Isomers may have different structures., and they may have different properties. We know that branched chains have lower boiling points then straight ones. Therefore to make sure that isomers do not effect the experiment only one isomer from each alcohol will be tested. Volume of Water To keep this variable constant the same volume of water for each experiment will be used. Mass of Ceramic Wool To keep this variable constant the same mass of ceramic wool will be used. Container To keep this variable constant only one container will be used for the whole experiment Height of Container To keep this variable constant the container will remain at the same height from the top of the crucible in each experiment Output Variables As a result of varying the alcohol (the input variable I am testing) ...read more.

Middle

One of the properties that alcohols have is they combust readily with oxygen forming Combustion is the burning, defined in chemical terms as the rapid combination of a substance with oxygen, accompanied by the evolution of heat and usually light. A slow-burning candle flame and the explosion of a mixture of petrol vapour and air are extreme examples of combustion. Combustion is an exothermic reaction ( exothermic reaction) as heat energy is given out. Exothermic reactions give out energy to their surroundings, hence the rise in temperature shown on the thermometer (a close surrounding). In an Exothermic reaction the products have a lower energy than the reactants ENERGY TIME As mentioned in the input section a mole will be the unit used to keep the volume input constant. A mole is the SI unit (symbol mol) of the amount of a substance. It is defined as the amount of a substance that contains as many elementary entities (atoms, molecules, and so on) as there are atoms in 12 g of the isotope carbon-12. One mole of an element that exists as single atoms weighs as many grams as its atomic number (so one mole of carbon weighs 12 g), and it contains 6.022045 x 1023 atoms, which is Avogadro's number. Below is my working for the masses that will be used in this experiment Ar (C12, H1, O16) methanol (CH3OH)=12+4x1+16=32g ethanol (C2H5OH)=2x12+6x1+16=46g propanol (C3H7OH)=3x12+8x1+16=60g butanol (C4H9OH)=4x12+10x1+16=74g Hexanol (C6H13OH)=6x12+14x1+16=102g Since these values are quite large meaning that the experiment will take longer to conduct, and increase problems I will use a hundredth of these values ...read more.

Conclusion

Keep alcohols as far away from Bunsen as possible. Bunsen should remain on safety yellow flame at all times. Handle crucible with tongs only, Remember it is hot. Make sure alcohols are left in fume cupboard, do not mix the pipettes. Insure that after using an alcohol the stopper is placed back on. The sinks must be left clean after the experiment is finished and the tables should be wiped. All apparatus that does not require cleaning should be returned to the correct place. Method: No changes to (see page in PLAN as a reference) SKILL O~ OBTAINING EVIDENCE Results: Raw Data Repeat 1 Repeat 2 Alcohol, a hundredth of a mole Start Temperature (�C) End Temperature (�C) Start Temperature (�C) End Temperature (�C) Methanol 74 84 57 65 Ethanol 69 83 60 78 Propan-2-ol 67 89 76 94 Butan-2-ol 55 81 59 90 Hexanol 21 57 24 58 Processed Data Repeat 1 Repeat 2 Alcohol, a hundredth of a mole Start Temp. (�C) End Temp.(�C) Rise in Temp. (�C) Start Temp. (�C) End Temp.(�C) Rise in Temp. (�C) Avg. rise in Temp. (�C) Energy (kJ/mol) Methanol 74 84 10 57 65 8 09.0 189.0 Ethanol 69 83 14 60 77 17 15.5 325.5 Propan-2-ol 67 89 22 76 94 18 20.0 420.0 Butan-2-ol 55 81 26 59 90 31 28.5 598.5 Hexanol 21 57 36 24 58 34 35.0 735.0 SKILL A~ANALYSING AND CONSIDERING EVIDENCE continued... Conclusion: SKILL E~EVALUATING Evaluation: Nathaniel Caiden Chemistry SC1 Investigating the factors that affect the amount of energy released when an alcohol burns Page 1 of 10 ...read more.

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