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To find out the enthalpy change of combustion by burning butanol and enthalpy.

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Introduction

Enthalpy Change of Combustion Aim To find out the enthalpy change of combustion by burning butanol and enthalpy. The standard enthalpy of combustion is the enthalpy change when one mole of an element or compound reacts completely with oxygen under standard conditions. In practice it is not possible to achieve complete combustion under standard conditions measurements are taken under experimental conditions; then a value for the enthalpy change is determined. During chemical reactions when bonds break, energy is absorbed. When bonds form, energy is released. The enthalpy change of combustion is the amount of enthalpy change when one mole of an element or compound reacts completely with oxygen under standard conditions the standard conditions is the pressure of 100kPa and temperature of 298k. ...read more.

Middle

I measured out 500cm3 of with a measuring cylinder and then I poured this into the calorimeter. I placed the thermometer in the calorimeter and then I measured the temperature of the water and then placed the burner underneath the calorimeter and lighted the burner. I used a stirrer through out to even the temperature of the H2O When bubbles appeared in the calorimeter I put out the burner and took the temperature again. This was to make sure no H2O were lost due to boiling thereby keeping the mass of H2O constant. This was repeated again for the ethanol I made sure I used different burners so not to mix the ethanol and butanol. ...read more.

Conclusion

44.1Kj ? 46g ? x x = 44.1 x 46 2.25 = 901.6Kj So 901.6 Kj Of any given amount by 1 mol = ?HC = 901.6 Kj mol-1 Results for butanol Mass of burner 109.01g Mass of burner and ethanol 110.52g Mass of ethanol 1051g Volume of water 500ml ==> 500g Temp of water at start 27 oC Temp of water at the end 42 oC Temp rise 15oC E = mc?T = 500 x 4.2 x 15 = 31500j ? 31.5Kj 1 mol of butanol =74g 1.51g ? 31.5Kj ? 74g ? x Kj x = 74 x 31.5 1.51 = 1543.7Kj mol-1 So 1543.7Kj of any given amount by 1 mol = ?HC = 1543.7Kj mol-1 Alex Mcghie ...read more.

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