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:
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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.
I will need to ensure that I conduct the experiments safely. As
alcohols are very dangerous and highly flammable I will wear my safety
goggles at all times. I will need to keep all lose items off clothing
tucked in. the lids on the alcohol's must be kept on at all times to
prevent evaporation or any spillage's.
Apparatus
·Retort Stand
·Clamp
·Copper container
·25ml measuring cylinder
·Selection of fuels, methanol, butanol, ethanol and pentanol
·Thermometer
·Water
·Heat proof mat
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Method
·Collect and set up apparatus as shown in the diagram
·Measure 20ml of water in the measuring cylinder
·Pour into copper container
question: Will the temperature of the water affect the speed of the dissolving Alka Seltzers?
Thermodynamics is essentially how heat energy transfers from one substance to another. In “Joe Science vs. the Water Heater,” the temperature of water in a water heater must be found without measuring the water directly from the water heater. This problem was translated to the lab by providing heated water, fish bowl thermometers, styrofoam cups, and all other instruments found in the lab. The thermometer only reaches 45 degrees celsius; therefore, thermodynamic equations need to be applied in order to find the original temperature of the hot water. We also had access to deionized water that was approximately room temperature.
== = Hess’s law of heat summation states that the value of DH for a reaction is the same whether it occurs directly or as a series of steps. This principle was used to determine the change in enthalpy for a highly exothermic reaction, the combustion of magnesium metal. Enthalpy changes for the reactions of Mg in HCl (aq) and MgO (s) in HCl (aq) were determined experimentally, then added to that for the combustion of hydrogen gas to arrive at a value of –587 kJ/mol Mg.
Does changing the length of the carbon chain effect the heat of combustion of water when heated for 2 minutes?
on how long it takes to heat up. If we heat a large volume of water it
under. It was nailed shut, but the nails had some give on one side where I could work
water has risen to 60°c I will then put the lid on the spirit burner
water has had equal amounts of time for it to heat up, again I will
-2152.7 x (56.1 / 1.37) = -88150.7 J.mol. 1. H = -88.15 kJ.mol. Hess' law states that: 1"The total enthalpy change for a chemical reaction is independent of the route by which the reaction takes place, provided initial and final conditions are the same.
cm∆T where c is the specific heating capacity of water (4.17 Jg-1K-1) -m is the mass of water, in g -∆T is the change of temperature of the water Apparatus Apparatus I will use Size of the apparatus Value /quantity distill water / >3 litres, as much as possible* thermometer 0-110C thermometer 1 measuring cylinder 100 cm3 1 electronic balance correct to 2 decimal places 1 Bunsen burner / 1 draught shielding each approx. 20cm x 20cm 5 metal calorimeter *** 4 clamp about 1 meter 6 spirit burner with wick / 4 match/wooden stick / as many as possible burner cap / 4 tile as big as possible 1 Propan-1-ol / half filled the spirit burner * Butan-1-ol / half filled the spirit burner * Butan-2-ol / half filled the spirit burne * Cyclohexanol / half filled the spirit burner * ***-I will find out in preliminary test *-Half filled the spirit burner because alcohol should be away from
For the sample calculations, let’s use the marshmallow as an example. Its initial mass was 0.66 grams and its final mass was 0.36 grams. To calculate the amount burned, subtract 0.36 from 0.66 to get 0.30 grams. (Mass burned = mi- mf). To find the marshmallow’s change in temperature, use the formula (ΔT =
The objective of this experiment was to identify a metal based on its specific heat using calorimetry. The unknown metals specific heat was measured in two different settings, room temperature water and cold water. Using two different temperatures of water would prove that the specific heat remained constant. The heated metal was placed into the two different water temperatures during two separate trials, and then the measurements were recorded. Through the measurements taken and plugged into the equation, two specific heats were found. Taking the two specific heats and averaging them, it was then that
be yes as I will then be able to use enthalpy change of reaction to
This is expressed as Δ +ve (delta positive). If the total energy put in is less than the energy created, then the substance warms up (it is exothermic). This is expressed as Δ -ve (delta negative). I will investigate eight different alcohols using an alcohol or spirit burner, to measure the energy change during burning by measuring the change in temperature of some water held in a container.
Heat energy is transferred through three ways- conduction, convection and radiation. All three are able to transfer heat from one place to another based off of different principles however, are all three are connected by the physics of heat. Let’s start with heat- what exactly is heat? We can understand heat by knowing that “heat is a thermal energy that flows from the warmer areas to the cooler areas, and the thermal energy is the total of all kinetic energies within a given system.” (Soffar, 2015) Now, we can explore the means to which heat is transferred and how each of them occurs. Heat is transferred through conduction at the molecular level and in simple terms, the transfers occurs through physical contact. In conduction, “the substance