Chemistry genius needed?
2018-01-19 11:47 am
(a) Which of the ions Rb + , Mg 2+ , Na + will have the larg est heat of hydration? Which the smallest? (b) Of the two compounds Mg(NO 3 ) 2 and Sr(NO 3 ) 2 , which has the stronger intermolecular forces? (c) Of the two compounds F 2 and ClF, which has the stronger intermolecular forces?
回答 (2)
2018-01-19 3:41 pm
(a)
For cations carrying equal charges, the smaller the cationic size, the larger the hydration energy is. As the size of Na⁺ ion is smaller than that of Rb⁺ ion, Na⁺ ion has larger hydration energy than Rb⁺ ion.
For cations with similar sizes, the greater the charge carried by cation, the larger the hydration energy is. As each Mg²⁺ ion carries 2 positive charges while each Na⁺ ion carries 1 positive charges only, Mg²⁺ ion has larger hydration energy than Na⁺ ion.
Therefore, among the 3 given cations, Mg²⁺ ion has the largest heat of hydration energy, and Rb⁺ ion has the smallest hydration energy.
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(b)
Both Mg(NO₃)₂ and Sr(NO₃)₂ are ionic compounds. They consist of opposite ions but not molecules. Therefore, there is no intermolecular forces in Mg(NO₃)₂ or Sr(NO₃)₂.
If the strengths of ionic bonds are compared, the ionic bonds of Mg(NO₃)₂ is stronger than that of Sr(NO₃)₂. As Mg²⁺ ion is smaller in size than Sr²⁺ ion, the interionic distance in Mg(NO₃)₂ is smaller than that in Sr(NO₃)₂. The shorter the interionic distance, the stronger the electrostatic forces between the opposite ions are. Therefore, Mg(NO₃)₂ has the stronger ionic bonds.
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(c)
The larger the molecular sizes, the strong the intermolecular forces are. As ClF has a larger molecular size than F₂, ClF has stronger intermolecular forces than F₂.
Furthermore, IF molecule is polar while F₂ molecule is non-polar. For molecules with similar sizes, substance with polar molecules has stronger intermolecular forces than substance with non-polar molecules. Therefore, ClF has further stronger intermolecular forces than F₂.
For cations carrying equal charges, the smaller the cationic size, the larger the hydration energy is. As the size of Na⁺ ion is smaller than that of Rb⁺ ion, Na⁺ ion has larger hydration energy than Rb⁺ ion.
For cations with similar sizes, the greater the charge carried by cation, the larger the hydration energy is. As each Mg²⁺ ion carries 2 positive charges while each Na⁺ ion carries 1 positive charges only, Mg²⁺ ion has larger hydration energy than Na⁺ ion.
Therefore, among the 3 given cations, Mg²⁺ ion has the largest heat of hydration energy, and Rb⁺ ion has the smallest hydration energy.
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(b)
Both Mg(NO₃)₂ and Sr(NO₃)₂ are ionic compounds. They consist of opposite ions but not molecules. Therefore, there is no intermolecular forces in Mg(NO₃)₂ or Sr(NO₃)₂.
If the strengths of ionic bonds are compared, the ionic bonds of Mg(NO₃)₂ is stronger than that of Sr(NO₃)₂. As Mg²⁺ ion is smaller in size than Sr²⁺ ion, the interionic distance in Mg(NO₃)₂ is smaller than that in Sr(NO₃)₂. The shorter the interionic distance, the stronger the electrostatic forces between the opposite ions are. Therefore, Mg(NO₃)₂ has the stronger ionic bonds.
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(c)
The larger the molecular sizes, the strong the intermolecular forces are. As ClF has a larger molecular size than F₂, ClF has stronger intermolecular forces than F₂.
Furthermore, IF molecule is polar while F₂ molecule is non-polar. For molecules with similar sizes, substance with polar molecules has stronger intermolecular forces than substance with non-polar molecules. Therefore, ClF has further stronger intermolecular forces than F₂.
2018-01-19 11:48 am
Good luck finding one on here.
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