• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

enthalpy change

Extracts from this document...

Introduction

Determining the Enthalpy change for the thermal decomposition of Calcium Carbonate The aim of this investigation is to determine the enthalpy change for the following reaction: CaCO3 � CaO + CO2 (s) (s) (g) The above reaction takes place when calcium carbonate undergoes thermal decomposition. I will calculate the enthalpy change of the reaction by an indirect method based on Hess's law. Enthalpy change ?H is the measure of heat change at a fixed pressure and temperature. It is known as the standard molar enthalpy change of a reaction and is measured in kilojoules per mole. Hess's law states that the total enthalpy change for a chemical reaction is the same, whatever route is taken, provided that the initial and final conditions remain constant. The diagram below outlines how I expect to calculate the enthalpy change of the reaction using an indirect method. ?H3 CaCO3(s) CaO(s) + CO2(g) HCl HCl ?H1 ?H2 CaCl2 (aq) Calcium oxide and calcium carbonate both react readily with 2mol dm? � hydrochloric acid solutions. The temperature changes during these two reactions can be measured and the enthalpy changes ?H1 and ?H2 can be calculated. ?H3 can be calculated using the Hess's cycle above as ?H1- ?H2 = ?H3 Below are the results tables that I recorded after carrying out the procedure for both calcium carbonate and calcium oxide. ...read more.

Middle

Number of Moles = Mass of Element (g) / Relative Atomic Mass of Element = 2.6 / 100.1 = 0.025974025 Here the mass of the element is 2.6 and relative atomic mass is the sum of the relative atomic masses of each of the elements of which calcium carbonate is composed of. Relative atomic mass of Calcium carbonate: CaCO3 = 40.1+12 + (16 x 3) = 100.1 ?H1= 0.22092 / 0.025974025 = 8.504650319 KJ mol? � ?H1= -8.505 KJ mol? � (to 3.dp) The value for the enthalpy change is negative because energy is lost to the surroundings hence it is an exothermic reaction. I will now calculate the enthalpy change that occurs between the reaction of calcium oxide and hydrochloric acid. ?H= mc?T ?H2= 51.4 x 4.2 x 11 = 2374.68 J = 2.37468 KJ Number of Moles in CaO= 1.4 / 56.1 = 0.024955436 ?H2= 2.37468 / 0.024955436 = 95.15682275 KJ mol? � ?H2= -95.157 KJ mol? � (to 3.dp) Now that I have calculated ?H1 and ?H2 I am able to calculate ?H3. ?H3= ?H1- ?H2 = -8.505-(-95.157) ?H3= 86.652 KJ mol? � From the result above we can see that the reaction when calcium carbonate is heated is an endothermic reaction. An endothermic reaction is when energy has been taken in from the surroundings. ...read more.

Conclusion

or limitations of the equipment used. Probably the biggest measurement error that occurred in the experiment was with regards to the temperature change that take place during a reaction. This was because it was virtually impossible to get a more reliable answer than that to the nearest whole number. It would have been very unlikely that the true values of the temperatures to be a whole value therefore this would have caused error in my result. To solve this problem I could have used a different type of thermometer, such as a digital thermometer that gives a reading which is more accurate than that to the nearest whole number. Another measurement error that could have taken place was when measuring the masses of my substances. I only measured the masses of the substance to one decimal place, which wasn't very accurate to give me a more reliable result I should have measured masses up to more significant figures. To make the experiment more accurate I could have repeated the investigation more times, from the results of each separate experiment I could then have been able to calculate an average of my enthalpy changes. Overall I feel I that the experiment went relatively well as I have done some research and found that other people have come to the same conclusion as me, which is that the thermal decomposition of calcium carbonate is an endothermic reaction. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Physical Chemistry section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Physical Chemistry essays

  1. Investigating the Rate of the Reaction between Bromide and Bromate Ions in Acid Solution

    I will have a solution of 5 g dm-3 methyl orange to use, and in both solutions C and D this needs to be 0.001%. Since the relative formula mass of methyl orange is 327.34g, this means that I will require 20cm3 of 5 g dm-3 of methyl orange in

  2. Investigating how concentration affects the rate of a reaction between Calcium Carbonate and hydrochloric ...

    I then got all my equipment ready like I did for the fist experiment. When everything was ready I repeated the experiment exactly the same as the first time recording my results until I had matching results with all of the acid molars.

  1. Investigating how concentration affects rate of reaction

    32.1 = 32.1 O4 = 4 x 16.0 = 64.0 = 98.1 grams needed = (1 x 98.1 x 250) 1000 = 24.525g dissolved in enough distilled water to make 250ml of solution. 0.0001M phenol: C6H5OH: C = 6 x 12.0 = 72.0 H = 6 x 1.0 = 6.0

  2. Magnesium and hydrochloric acid react together readily. Plan and carry out an investigation testing ...

    Acid used 3 molar. Time intervals every 15.0 seconds. Time (in seconds) Amount of hydrogen (cm cubed) 0.0 Experiment ended too quickly 0.06 g of Magnesium ribbon, 50ml of hydrochloric acid. Acid used 3 molar. Time intervals every 5.0 seconds.

  1. Science at Work Research . Dulux Paints, a Hospital, a leisure centre and a ...

    The paste is transferred to a large kettle where it is agitated with the right amount of solvent to match the paint desired. Canning the paint: The paint is then pumped into the canning room. Empty cans are rolled horizontally onto labels the set upright for the paint to be pumped into them.

  2. Determining the Relative Atomic Mass of Lithium

    � Lithium hydroxide can cause severe irritation and corrosive tissue damage. Concentrated concentrations of lithium hydroxide may rapidly cause deep burns if there is skin contactt � HCl is corrosive, may cause severe burns to all body tissue. May be fatal if swallowed or inhaled Method I got 25cm3 of

  1. Investigating the rate of reaction between marble chips (calcium carbonate) and hydrochloric acid.

    Step8: Repeat Steps2-7 but with acid concentration 2.0M Step9: Repeat Steps2-7 but with acid concentration 1.5M Step10: Repeat Steps2-7 but with acid concentration 1.0M Step11: Repeat Steps2-7 but with acid concentration 0.5M My results will be collected and recorded in a table similar to this: Weight of CaCo3 (g)

  2. Individual investigation - Reaction to be studied Rate of reaction between propanone and ...

    * Propanone solution, 1.00moldm-3 (50cm3) * Iodine solution, 0.02moldm-3 (100cm3) * Sodium Thiosulphate (VI) solution, 0.02moldm-3 (50cm3) * Sodium hydrogen carbonate solution 0.02moldm-3 (50cm3) * Hydrochloric acid, 2.00 moldm-3 (50cm3) * Stopwatch * White tile * Freshly made starch solution (2cm3) Methods: Steps used in "Quenching": 1.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work