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30 Cards in this Set
- Front
- Back
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Lattice enthalpy |
The enthalpy change that accompanies the formation of one mole of an ionic compound from its gaseous ions under standard conditions |
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Why is lattice enthalpy exothermic? |
Energy is released when bonds formed |
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What diagram is used to represent to energy changes? |
Born-Haber cycle |
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What's hess's law |
That if a reaction can fake place by more than one route and the initial and final conditions are the same, then the total enthalpy change is the same for each route |
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Standard enthalpy change of formation |
Is the enthalpy change that takes place when one mole of a compound is formed from its constituent elements in their standard states under standard conditions |
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First ionisation energy |
The enthalpy change accompanying the removal of one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions |
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What's the first electron affinity? |
The enthalpy change accompanying the addition of one electron to each atom in one mole of gaseous atoms to form one mole of gaseous 1- ions |
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Why can lattice energies not be calculated directly? |
Impossible to form one mole of an ionic lattice from gaseous ions |
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What do upwards arrows represent |
Endothermic!! |
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Standard enthalpy change of solution |
The enthalpy change that takes place when one mole of a compound is dissolved in water under standard conditions |
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What happens during hydration? |
Gaseous ions bond with the water molecules |
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Standard enthalpy change of hydration |
The enthalpy change that takes place when one mole of isolated gaseous ions is dissolved in wafer forming one mole of aqueous ions under standard conditions |
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What happens to lattice enthalpy when ionic size increases |
Attraction between oppositely charged ions decreases, lattice enthalpy becomes less negative and melting point decreases |
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What does a large negative value for lattice enthalpy show |
It shows that there are strong electrostatic forces of Attraction between oppositely charged ions in the lattice |
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What is the enthalpy change of atomisation and what kind of process is it |
It is the enthalpy change that takes place when one mole of gaseous atoms formed from the element in a standard state. It is always endothermic because Bonds have to be broken |
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What is the first ionisation energy |
It is the enthalpy change accompanying the removal of one electron from each atom in 1 mole of gaseous atoms to form one mole of gaseous 1 + ions |
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Why is the first electron affinity exothermic? |
Because the electron is attracted into the outer shell of an atom by the nucleus he was |
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Why is the second electron affinity endothermic |
It is endothermic because electron is repelled by the 1- ion. The repulsion therefore has to be overcome |
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Standard enthalpy change of solution |
It is a salty change that takes place when one mole of a compound is dissolved in water under standard conditions |
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What is a standard enthalpy change of hydration |
It is the enthalpy change that takes place when one mole of isolated gaseous a ions is dissolved in water forming one mol of aqueous ions |
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What are the general properties of ionic compounds |
High melting and boiling points, soluble in polar solvents, conduct electricity when molten or in aqueous solution |
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What is the effect of increasing ionic size on lattice enthalpy |
Is the ionic radius increases, the attraction between ions decreases.. therefore causing the lattice energy to become less negative and causing the melting point to decrease |
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What is the effect of increasing ionic charge on lattice enthalpy |
Is the ionic charge increases the attraction between the ions increases, there for the lattice enthalpy becomes more negative and the melting point increases |
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What is entropy |
When energy is dispersed and becomes more spread out where there is more disorder |
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What are the units for entropy |
Joules per Kelvin per mole |
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How can standard entropy change be calculated |
(Products) - (reactants) |
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What is the Gibbs equation |
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What is free energy change |
The changing energy during a chemical reaction. It is made up of two types of energy being the enthalpy change and the entropy change |
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How do you know whether a reaction is feasible |
when there is a decrease in free energy. ◇G<0 |
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What is the limitation of predictions made for feasibility |
The fact that activation energy is not taking into account Only the thermodynamic feasibility is considered whereas predicting feasibility doesn't take into account the kinetics or the rate of reaction |
