Answer:
151.94 u
Explanation:
The atomic mass of Eu is the <em>weighted average</em> of the atomic masses of its isotopes.
We multiply the atomic mass of each isotope by a number representing its relative importance (i.e., its <em>percent abundance</em>).
The atomic masses of Eu-151 and Eu-153 are 150.92 u and 152.92 u, respectively.
Set up a table for easy calculation.
0.4803 × 150.92 u = 72.472 u
0.5197 × 152.92 u = <u> 79.473 u
</u>
TOTAL = 151.94 u
Answer: the valence electron for phosphorus is 5. To achieve an octet electron arrangement, it needs to lose 5 electrons or gain 3 electrons. It is easier to gain 3 electrons than to lose 5 electrons. So phosphorus has to gain 3 electrons.
Explanation:
Hope it helps sorry if it doesn't
Answer:
ΔHrxn = 178.3 kJ/mol
Explanation:
Using Hess's law, you can obtain ΔHrxn from ΔHf of products and reactants, thus:
<em>Hess's law: </em>
ΔHrxn = <em>∑nΔHf products - ∑nΔHf reactants</em>
<em>Where n are moles of reaction</em>
<em> </em>
Thus, from the reaction:
CaCO₃(s) → CaO(s) + CO₂(g)
ΔHrxn = <em>ΔHf </em>CaO(s)<em> + ΔHf </em>CO₂(g)<em> - ΔHf </em>CaCO₃(s)
ΔHrxn = -635.1kJ/mol + (-393.5kJ/mol) - (-1206.9kJ/mol)
<em>ΔHrxn = 178.3 kJ/mol</em>
I think Alcohol would be the correct answer, but i'm not too sure since my mind is fuzzy about chemistry
