You and your lab partner are asked to determine the density of an aluminum bar. The mass is known accurately to 4 significant fi
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<u>Answer:</u> The for the reaction is -1835 kJ.
<u>Explanation:</u>
Hess’s law of constant heat summation states that the amount of heat absorbed or evolved in a given chemical equation remains the same whether the process occurs in one step or several steps.
According to this law, the chemical equation is treated as ordinary algebraic expressions and can be added or subtracted to yield the required equation. This means that the enthalpy change of the overall reaction is equal to the sum of the enthalpy changes of the intermediate reactions.
The given chemical reaction follows:
The intermediate balanced chemical reaction are:
(1)
( × 4)
(2)
The expression for enthalpy of the reaction follows:
Putting values in above equation, we get:
Hence, the for the reaction is -1835 kJ.
Answer:
(a) a = 5.08x10⁻⁸ cm
(b) r = 179.6 pm
Explanation:
(a) The lattice parameter "a" can be calculated using the following equation:
<em>where ρ: is the density of Th = 11.72 g/cm³, N° atoms/cell = 4, m: is the atomic weight of Th = 232 g/mol, Vc: is the unit cell volume = a³, and </em><em>: is the Avogadro constant = 6.023x10²³ atoms/mol. </em>
Hence the lattice parameter is:
(b) We know that the lattice parameter of a FCC structure is:
<em>where r: is the atomic radius of Th</em>
Hence, the atomic radius of Th is:
I hope it helps you!