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

Investigating enthalpy Change - During this investigation I will be burning a selection of different alcohol's to heat a container of water.

Extracts from this document...


Investigating enthalpy Change During this investigation I will be burning a selection of different alcohol's to heat a container of water. I will be burning four alcohols, methanol, ethanol, propanol and butanol. The aim of the experiment is to find out how much energy is produced when these alcohols are burnt and to see if there's a relation between how many, and how strong the bonds are between molecules in the elements burnt, and how quickly the water is heated up. To put it simply, we will see if the enthalpy would increase per extra CH? added Any form of burning is an exothermic reaction; this means that heat is given out as a result. This means that the reactants energy is higher than that of the product. Alcohols react with oxygen in the air to form water and carbon dioxide. The energy is given out when new bonds are formed between the water and carbon dioxide molecules. The amount of energy produced by such exothermic reactions can be calculated by using this formula: Delta H is the amount of enthalpy (heat energy), M is the mass of the water, 4.2 is the specific temperature capacity of water (the amount of joules required to heat water by 1�C and Delta T is the waters change in temperature. ...read more.


For example Ethanol has the formula C H OH. In this formula you have five C-H bonds, one C-C bond, one C-O bond and one O-H bond (all of which are single bonds). To separate these types of bonds you require a certain amount of energy which I will show in a table. TYPE OF BOND ENERGY REQUIRED BREAKING THE BOND (kJ) C-H 410 C-O 360 O=O 496 O-H 510 C-C 350 C=O 740 To separate C-H bond you need to apply 410 joules of energy. There are five of these bonds in ethanol so you multiply 410 by five to get 2050 joules. You do these calculations for all the other types of bonds that make up ethanol, add them all together and you get 3270 joules. All of the other alcohols can be broken up in this way. Below is a table showing the energy required to break up the bonds in each alcohol. Type of alcohol Energy required to break the bonds in the alcohol (KJ) Methanol 2100 Ethanol 3270 Butanol 4560 Pentanol 6420 As you can see, a longer molecule takes more energy to break its bonds, in this case Butanol, compared to a smaller molecule, methanol, which requires less energy to do so. I can come to predict that the longer the molecular structure in the alcohol the more energy it will take to remove the bonds. ...read more.


Below are some possible reasons why my results were much lower than the theoretical values: o Some of the apparatus may have absorbed some of the heat energy given off by the fuel. Such as the beaker getting hot. o Some of the heat energy may have been taken away by gusts of winds or may have escaped into its surroundings. o Some of the water may have evaporated as a result of the high temperatures. This would mean that there would be less water to heat, making the water get hotter quicker. o The flame size changed due to the type of alcohol; hence it was a different distance away from the beaker each time. o And lastly incomplete combustion would have acted as a major factor into reducing the amount of energy release. I would not extend this investigation by experimenting with more alcohols as it is clear that the trend identified is likely to continue as long as the chain of molecules for each alcohol is increasing. I would extend this investigation by investigating other organic compounds, such as hydrocarbons, to see if they behave similarly. Likewise experimenting with the calorific values of different foods would also make good experiments. This is where the numbers of calories for each type of food will be measured and investigated. Michael South Bond Energy ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Organic 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 GCSE Organic Chemistry essays

  1. To determine which alcohol, out of ethanol and propanol, is the better fuel. By ...

    Although the foil acts as a good insulator it could not prevent the vast amount of heat that was lost. The good point about my procedure was that I used electronic devices when available for measuring masses and temperature. The electronic balance gave an accurate figure to 2 d.p., while

  2. To find how much energy is produced when burning different alcohols.

    The flame size changed due to the type of alcohol, hence it was a different distance away from the beaker each time. Numbers 1 - 10 would decrease the reading and Numbers 11 - 14 would increase the reading.

  1. Comparing the enthalpy changes of combustion of different alcohols.

    = (12x1) + (4x1) + (1 x 16) = 32g 3.15g is the first reading for the replicate one of methanol for the change in mass of the fuel. 3.15g 32g = 0.0984375 moles A mole is 6.02 x 1023 atoms of the chemical. It is also known as Avogadro's constant.

  2. Esters. Esters are formed from an alcohol and carboxylic acid; this is an ...

    than testing on humans but if the people are going to test on animals that make it the same way you would test on humans making it as painless as possible. For my reactions of dilute ethanoic acid test my results were that: Yellow litmus turns red in ethanoic acid,

  1. Investigate the enthalpy change of different alcohol

    Record the maximum temperature so that a drop in temperature caused by leaving the calorimeter too long would not mislead us to the inaccurate reading. 4. Close the cap to the burner when not used, because short-chain alcohol is very volatile.

  2. Investigating the energy released from burning different alcohols.

    painted black, this heat will also be transferred to the water through conduction. The end of the thermometer will be placed in the water; however, it would not be touching the copper. If it does, the thermometer would be measuring the temperature of the copper not the water.

  1. The Energy Content Of Different Fuels

    = 1.9 g 3. Molar mass of CH3OH = 32 No. of moles = mass Molar mass No. of moles = 1.9 / 32 = 0.059375 moles of fuel used 4. Energy used & produced to = mass of water X S.H.C X Temp rise heat the water Energy = 25 X 4.2 X 70 = 7350 joules 5.

  2. GCSE Chemistry Revision Notes - everything!

    The sharp taste of fizzy drinks is caused by the carbonic acid, but as the carbon dioxide bubbles out, the drink tends to taste sweeter. Nitrogen Nitrogen is a very unreactive gas, usually under normal conditions; it does not react with the oxygen in the air.

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