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# Enthalpy practical write up

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Introduction

An investigation on the effect of melting solidified H2O to change the enthalpy and also the physical state of the solidified H2O Name: Casey Going Date: 26/07/09 Experimental Design Focus Question - what is the effect of increasing the mass of ice cubes on the temperature change (enthalpy) when an endothermic reaction takes place? Hypothesis -The larger ice cubes with a volume of 16cm3 will have larger enthalpy then the smaller ice cubes with a smaller volume of 4cm3. Theory - Enthalpy is the measure of heat content in a particular system. Heat flows between the system and the surroundings. q=m.Cs.?T Is the formula that will be needed to be used to calculate the enthalpy change of the products and the reactants. Where q is the heat transfer m is the mass, Cs is the specific heat capacity which for water is 4.1816J/g-C� joules and ?T which is the temperature change. ...read more.

Middle

The ice takes in the heat making the surroundings cold by also raising the temperature of the ice so that it melts. This reaction is most probably endothermic as ?T is negative. The larger ice cubes will have a larger volume but also a larger surface area. The larger ice cubes should theoretically melt slower and therefore have a smaller final temperature when the time limit of 20 minutes has ended. Variables - Variables identified Type of variable Treatment Volume of ice cube Independent variable The ice cubes will be 1cm3, 4cm3, 9cm3, 16 cm3 and 25cm3. The size difference will result in a different overall enthalpy change as it likely to have a different final temperature. Temperature change Dependent Variable The final temperature will be measured with a temperature probe using the data studio software Heat lost through container Controlled Variable An bowl will be used so that as little heat as possible will be lost to the surroundings Room temperature Controlled Variable The room temperature will be kept at 21 ...read more.

Conclusion

individual ice cube capsule, remembering to do this for 1 x 1 cm, 2x2 cm, 3x3cm, 4x4 cm and 5x5cm ice cube trays. 2. Freeze until ice cubes are completely solid through or overnight 3. Once ice cubes are frozen place one inside the bowl remembering to leave the other ice cubes in the freezer so that they will not melt 4. Once the ice cube is placed into the bowl measure the initial temperature of the ice cube. 5. Place bowl on top of hot plate and set to 2v 6. Heat the ice cube for 3 minutes 7. When the permitted time allowed for the ice to melt has ended, 3 minutes, measure the final temperature of the melted ice cube 8. Pour out melted ice water into the sink 9. Repeat steps 3-8 for 10 ice cubes of 1cm3, 4cm3, 9cm3, 16 cm3 and 25cm3 10. Use the formula q=m.Cs.?T to calculate heat transfer ?? ?? ?? ?? Casey Going Mrs Clemence Yr 11 HL Chemistry Enthalpy design prac ...read more.

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