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>
To calculate empirical formula, number of moles of different atoms calculated first:
Number of moles of Carbon , n=
=
=
= 0.220 mol
Number of moles H =
=
= 0.440 mol
Number of moles of oxygen =
=
= 0.440 mol
Ratio of carbon
=
= 1
Ratio of hydrogen
=
= 2
Ratio of oxygen
=
= 2
So, the empirical formula is CH₂O₂
Answer:
A
Explanation:
The octet rule refers to the tendency of atoms to prefer to have eight electrons in the valence shell. When atoms have fewer than eight electrons, they tend to react and form more stable compounds. When discussing the octet rule, we do not consider d or f electrons. Only the s and p electrons are involved in the octet rule, making it useful for the main group elements (elements not in the transition metal or inner-transition metal blocks); an octet in these atoms corresponds to an electron configurations ending with s2p6 .
