<span>19. Single displacement reactions are always redox reactions (they include reaction between an element and a compound where they will take place of another element in that compound).
20. It should be single displacement, where the displaced ion would form gas.</span>

4 0

3 years ago

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How do the atomic mass and atomic number compare for helium?

Sonja [21]

The atomic mass is greater than the atomic number.

4 0

4 years ago

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Which compound is an exception to the octet rule?

slavikrds [6]

Answer:

the answer is ClF3 on edge

Explanation:

8 0

3 years ago

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Name two compounds with more exothermic lattice energies than scandium oxide and justify your choice.

N76 [4]

Answer:

1 . $Al_2O_3$

2. $TiO_2$

Explanation:

The more stable the ionic compound, the more is it lattice energy.

The more the charge on the cation and the anion, the greater is the lattice energy.
The less the size of the cation and the anion, the greater is the lattice energy.

Scandium oxide ( $Sc_2O_3$ ) is an oxide in which $Sc^{3+}$ behaves as cation and $O^{2-}$ behaves as anion.

The compounds which has higher lattice energy than scandium oxide are:

1 . $Al_2O_3$

This is because the charge are same on the cation and the anion as in the case of the Scandium oxide but the size of the cation $Al^{3+}$ is smaller than $Sc^{3+}$ . Thus, this corresponds to higher lattice energy.

2. $TiO_2$

This is because the charge on the cation $Ti^{4+}$ is greater than that of $Sc^{3+}$ and also the size of the cation $Ti^{4+}$ is smaller than $Sc^{3+}$ . Thus, this corresponds to higher lattice energy.

3 0

3 years ago