How To Determine Which Compound Has The Highest Lattice Energy
Lattice Energy
Lattice energy evaluates the intensity of the ionic bonds present in an ionic compound. Information technology sheds light on several ionic solids' characteristics, such as their volatility, solubility, and hardness. Ionic solid lattice energy cannot be determined directly. However, it can be easily calculated using the Born-Haber wheel. The SI unit of lattice energy in kilojoules per mole (kJ/mol).
What is Lattice Free energy?
Ionic compounds are more than persistent because of the electrostatic forcefulness present between the two opposing ions. After creating ions, they come together to form an ionic compound. The energy released during this process is chosen lattice energy. In other words, lattice energy is the energy generated when an anion and a cation unite to produce i mole of an ionic compound. Therefore, nosotros may write.
A+ + B– → A+B– + Lattice energy
Alternatively, it tin be viewed as the free energy needed to endothermically break 1 mole of an ion crystal to gaseous ions in a infinite (vacuum). As a outcome, this corporeality has a positive value at all times.
While some sources depict lattice free energy differently, i.e., the amount of energy released during the exothermic formation of an ionic solid from its gaseous ionic components, this definition requires that lattice energy always has a negative value.
Equally a upshot, lattice energy can be defined as the energy released when gaseous ions react to form one mole of a solid ionic compound. It tin also refer to the free energy that enables 1 mole of a solid ionic compound to dissociate into its component gaseous ions. The lattice free energy of a particular ionic molecule might either be a positive or negative value, based on the definition we use.
Exothermic or Endothermic?
We can meet lattice energies as either exothermic or endothermic processes depending on the terminology nosotros apply. Every bit per the initial definition, the structure of the lattice energy value changes with the breakdown of an ionic chemical compound. Because this process uses energy, it is considered endothermic, which holds a positive value.
When a process produces heat, it is exothermic. According to the second definition, creating an ionic compound requires exothermic lattice energy, property a negative value.
Factors Affecting Lattice Energy
The ionic bond tenacity increases with an increase in the lattice energy. Additionally, the size or radius of the ions, as well as the charge of the ions, affect the lattice free energy.
a) Ionization radius
Lattice energy diminishes as the distance variable is increased. The increased distance betwixt large ions generally results in ionic compounds with decreased lattice energies. Larger lattice energies are produced in the ionic compounds of smaller ions. As a result, the lattice energy decreases equally the ion radius grows.
The graph of lithium halide'due south lattice energy is shown below. The lattice energy reduces as halide size grows down the group. It is considering when ions become larger, their nuclei become further apart. As a result, they are less attracted, resulting in less lattice free energy being produced.
b) Ionization charge
The lattice free energy increases as the ion accuse variable is increased. Accordingly, ions with higher charge intensities will result in ionic compounds with college lattice energies. Consequently, ions with weaker charges cause their compounds' lattice energies to autumn.
As a upshot of their stronger attraction to one another, lattice free energy rises as ion charge increases. Compared to +1 or -1 ions, +ii or -2 ions volition release more than lattice free energy. Here, we can observe that MgO's lattice free energy is significantly higher than NaCl.
Lattice Free energy Formula
The energy generated when two gaseous ions with opposite char ges come together to create an ionic solid is known equally lattice energy. The ii ions attract 1 some other, and this exothermic reaction releases free energy. Although lattice energy can be fairly circuitous, Coulomb's constabulary is frequently used to simplify it.
The lattice energy formula can exist stated every bit follows:
LE = kQ1Q2 / r
Where,
LE = lattice energy
k = 2.31 x 10-19 J-nm
Q1 and Q2 = the relative charges of the component ions in an ionic chemical compound
r = altitude or radius between the ion centers
Lattice Energy Formula Practice Question:
Q. Country the lattice energy of chlorine and sodium ions with a 1.0 nm distance between them?
Reply: In this instance, nm stands for a nanometer (10-9 m), and sodium and chlorine both create positive ions.
LE = kQ1Q2 / r
LE = ii.31 X 10-19 J-nm (+i) (-1) / 1.0nm
LE = -two.31 X 10-19 J
How to Calculate Lattice Free energy?
Then, how to find lattice free energy? Hess'south law (known equally the Built-in Haber cycldue east) calculates lattice energy. This constabulary states that no matter how many stages a reaction takes, the energy change is ever the same for that reaction. Therefore, the total energy required will exist the same whether an ionic chemical compound is formed in a few stages or all at once. For instance, the pure sodium and chlorine gas reactions produce sodium chloride crystals. Whether it reacts in a few stages or all at once, the change in the energy level will exist the aforementioned.
The Born-Haber bike for the crystallization of sodium chloride is shown beneath.
Hither are the steps involved in sodium chloride formation:
Phase 1:
The first stage entailed converting sodium from its typical solid state into a gaseous country.
Na(s) → Na(g) ΔHatom = +107 kJ/mol
This procedure is called atomization, and the energy alter that occurs during information technology is referred to equally atomization energy. Atomization free energy is the free energy needed to alter one mole of a gaseous atom from its initial state. The atomization energy in this stage is +107 kJ/mol.
Stage ii:
The second stage entailed splitting the chlorine molecule into gaseous chlorine atoms. The dissociation bond's energy is +122 kJ/mol.
i/2Cl2(g) → Cl(g) ΔHBe = +122 kJ/mol
Stage 3:
In the third stage, sodium is ionized while still in a gaseous state to produce positively charged sodium ions by giving upward an electron. The ionization energy in this phase is +494 kJ/mol.
Na(g) → Na+ (g) + e– ΔHIE1 = +494 kJ/mol
Phase 4:
In this stage, an electron is added to the chlorine atom to create a negatively charged chloride ion in a gaseous form. For this reaction, the electron released has an electron affinity of -349 kJ/mol.
Cl(g) + e– → Cl– (g) ΔHEA1 = -349 kJ/mol
Phase five:
The creation of sodium chloride from its gaseous ions is the last and fifth stage. It is necessary to make up one's mind the lattice energy produced during this functioning, which should be negative.
Na+ (g) + Cl– (chiliad) → NaCl(s) ΔHLE = -? kJ/mol
If the entire reaction takes a single stride, the rut formation is -4xi kJ/mol.
Na(s) + 1/2Clii(g) → NaCl(s) ΔHf = -411 kJ/mol
In accordance with Hess's law,
ΔHf = ΔHatom + ΔHBE + ΔHIE1 + ΔHEA1 + ΔHLE
⇒ -411 = 107 + 122 + 494 -349 + ΔHLE
⇒ ΔHLE = -785 kJ/mol
Therefore, sodium chloride has a lattice energy of -785 kJ/mol.
Take Yous Heard?
The Born-Haber cycle is a method used for analyzing reaction energies. The names Max Built-in and Fritz Haber were given in honor of the two German scientists who discovered it in 1919. Theastward bicycle concerns how a metallic—typically a Group I or Grouping 2 element—reacts with a halogen or some other non-metal element, like oxygen, to generate an ionic combination. The chief awarding of Born-Haber cycles is to compute lattice energy, which cannot be observed straight.
Lattice Energy Trend
In summation, the lattice energy tendency rises equally the ion accuse rises and the altitude or radius falls. More specifically, information technology rises through the lesser to top groups and from left to right throughout periods.
The post-obit graphic depicts trends in lattice energy from the periodic tabular array:
Conclusion
The lattice free energy can exist classified as the energy change when one mole of a crystalline ionic chemical compound is formed from its component ions, which are believed to be in the gaseous state. It gauges the compressive forces that hold ionic solids together. Numerous additional physical characteristics, including absorption, toughness, and volatility, ar e related to the magnitude of the lattice energy. The Born-Haber cycle estimates lattice free energy, which is typically impossible indirectly.
Frequently Asked Questions
1. What is lattice energy?
Lattice energy can be expressed as the specific amount of energy produced when the gaseous ions react during the generation of one mole of a solid ionic compound. It also refers to the energy that makes it possible for one mole of a solid ionic compound to split into its component gaseous ions.
two. Which chemical compound has the highest lattice energy?
Among these compounds, sodium fluoride (NaF) has the highest lattice free energy considering it contains ions with the same charge every bit sodium and because the lattice energy rises with the size of the ions.
three. Which compound has the lowest lattice energy?
Every bit ion size grows, the lattice energy drops. Cesium iodide has the largest cation and anion sizes compared to other compounds. Therefore, cesium iodide has the everyman lattice energy.
4. What uses exercise you run across for lattice energy?
Following are the common applications of lattice free energy:
- Lattice energy aids in determining the energy produced from a chemic when a certain number of ions come up together to class that complex.
- It is by and large employed to gauge the say-so of ionic solid substances.
- Ionic solids typically have loftier lattice energies, which increase their stability and make it difficult to interruption the bonds betwixt them in the circuitous.
Source: https://www.turito.com/blog/chemistry/lattice-energy
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