Titration Flashcards
(44 cards)
calorimetry
Measuring the amount of heat given out or taken in by a process, such as the combustion of a fuel.
decompose
If a substance decomposes, it breaks down into simpler compounds or elements.
electrolyte
A substance which, when molten or in solution, will conduct an electric current.
endothermic
Reaction in which energy is taken in from the surroundings.
enthalpy change
The change in the amount of heat as a result of a chemical reaction, such as combustion and neutralisation.
exothermic
Reaction in which energy is given out to the surroundings. The surroundings then have more energy than they started with so the temperature increases.
isotope
Atoms of an element with the same number of protons and electrons but different numbers of neutrons.
molar
The amount of something per mole. For example, ‘molar enthalpy change’ is the enthalpy change per mole.
mole
The amount of substance that contains the same number of particles as there are atoms in 12 g of carbon-12 (Avogadro’s constant 6.0 ×10²³).
product
A substance formed in a chemical reaction.
radioactive
When unstable atoms give off particles that can be harmful to humans.
radioactive decay
The process in which unstable atomic nuclei break apart or change, releasing radiation as they do so.
reactant
A substance that reacts together with another substance to form products during a chemical reaction.
voltage
The potential difference across a cell, electrical supply or electrical component. It is measured in volts (V).
Energy diagrams
Energy diagrams show the level of energy of the reactants and of the products. The bigger the difference between the energy of the reactants and the energy of the products, the more energy is given out or taken in.
Exothermic graph
In an exothermic reaction, the products are at a lower energy than the reactants. The difference between the energy of the reactants and the energy of the products is called the enthalpy change (∆H) of the reaction. For an exothermic reaction, the enthalpy change is always negative.
Endothermic graph
In an endothermic reaction, the products are at a higher energy than the reactants. This means that the enthalpy change of the reaction (∆H) is positive.
Calculating energy changes
Data from a calorimetry experiment can be used to calculate the molar enthalpy change of a reaction.
Use this equation to work out an energy change:
Energy transferred = mass of water heated × specific heat capacity of water × temperature rise
Bond energy calculations
You can calculate the energy change in a reaction using average bond energies. Bond energy is the amount of energy needed to break one mole of a particular bond.
To calculate bond energy step 1
Add together the bond energies for all the bonds in the reactants – this is the ‘energy in’.
To calculate bond energy step 2
Add together the bond energies for all the bonds in the products – this is the ‘energy out’.
To calculate bond energy step 3
Calculate the energy change = energy in – energy out.
Production of energy
Heat energy can be produced by burning fuels such as hydrogen. However, it can also be produced in other ways.
Radioactive isotopes
Some isotopes are radioactive, for example 235U. These substances can be used as fuels in nuclear power stations. They release energy as they turn into other elements through radioactive decay.
