Investigation into the Factors that Affect the Enthalpy Change During a Displacement Reaction
The Task
--------
To investigate the factors affecting the enthalpy change during a
displacement reaction.
Background Knowledge
====================
In this investigation a displacement reaction will be observed. A
displacement reaction occurs when more reactive metal displaces, (or
removes) a less reactive metal from a solution of its salt. Also known
as chemical bullying because a more reactive metal effectively bullies
the original metal out of its compound.
In this investigation zinc and copper sulphate will be reacted
together. Zinc is the more reactive metal here, so the copper is
displaced from the copper sulphate solution.
Zinc + Copper sulphate à Zinc sulphate + Copper
Zn (s) + CuSO4 (aq) à ZnSO4 (aq) + Cu (s)
After the reaction it will be observed that the solution will change
from blue to clear, colourless. The copper discharged will be observed
as a salmon pink deposit in the base of the vessel the reaction occurs
in.
Reactions like this can be used to purify metals that are low down in
the reactivity series. A more reactive metal can simply be added to
purify the less reactive metal, leaving it in its pure state.
Lead Oxide + Tin à Lead + Tin Oxide
In reality thought this process is hardly ever used, as the more
reactive metal is the left in an impure form, and thus must be reduced
by an even more reactive metal. As this is not economically viable
metals are generally reduced using electrolysis, which leaves them in
a pure state, and requires no expensive more reactive metals, just
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...pacity of
the solution (assume this equals 4.2 J/g/degrees Celsius), /T =
temperature change (estimated from extrapolation).
The results here show the heat energy in each reaction. To calculate
the enthalpy change one must account for the respective moles involved
in each reaction.
To equal out the number of moles simply multiply the results by the
respective amounts required to make them all amounts of Joules/1 mole.
When this calculation is performed on all the heat energy results
enthalpy change can be compared. In an accurate experiment the
enthalpy change when copper sulphate solution is reacted with zinc
powder should remain constant. By taking into account the number of
moles in each equation when multiplying the results will be brought
into proportion, so the enthalpy changes should be roughly equal.
== = 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.
The Effect of Temperature on the Rate of Reaction Between Hydrochloric Acid and Calcium Carbonate
During this reaction the solution gained heat. This is what we were monitoring. The reason why the solution gained heat is because the reaction lost heat. Energy is lost when two elements or compounds mix. The energy lost/ gain was heat. Heat is a form of energy as stated above in the previous paragraph. The sign of enthalpy for three out of the four reactions matches what was observed in the lab. For the last reaction, part four, the reaction gained heat not the solution like parts one through three. The negative enthalpy value for part four indicates that the reaction gained
Investigation of the heat energy produced by combustion of various alcohols. Aim: ---- To investigate how different alcohols produce different amounts of heat energy through combustion. I will be heating water using different alcohols as fuels and measuring the amount of fuel consumed.
= 3 ´ E(C-H) + 1 ´ E(C-O) + 1 ´ E(O-H) + 1.5 ´ E(O=O)
" This means that therefore the enthalpy change of a reaction can be measured by the calculation of 2 other reactions which relate directly to the reactants used in the first reaction and provided the same reaction conditions are used, the results will not be affected. We have the problem set by the experiment to determine the enthalpy change of the thermal decomposition of calcium carbonate. This is difficult because we cannot accurately measure how much thermal energy is taken from the surroundings and provided via thermal energy from a Bunsen flame into the reactants, due to its endothermic nature. Therefore, using the enthalpy changes obtained in reaction 1 and reaction 2 we can set up a Hess cycle.
Copper Oxide + Carbon Dioxide (CuCO3 = CuO + CO2) The reactivity series determines how fast this reaction occurs. The reactivity series is the order of metals in the periodic table. The most reactive metals are placed at the top of the reactivity series.
Investigating Factors Affecting the Heat of Combustion of Alcohols PLANNING SECTION Introduction ------------ Alcohols are organic substances, and consist of Hydrogen, Oxygen and Carbon. All alcohols are toxic but the amount that can be tolerated by the human body varies for different alcohols. For example drinking small amounts of Methanol can lead to blindness and even death.
Neutralization Experiment AIM:- To investigate how heat is given out in neutralizing sodium hydroxide (NaOH) using different concentrations of Hydrochloric Acid. Background Information:- Substances that neutralize acids are called alkalis. An acid is a substance that forms hydrogen ions (H+ ) when placed in water. It can also be described as a proton donor as it provides H+ ions. An example of an acid is hydrochloric acid (HCl), Sulphuric acid (H2SO4) etc.