Calculate the approximate enthalpy change , δh∘, for the combustion of methane: ch4+2o2⇌2h2o+co2 use the values you calculated in parts a to d, keeping in mind the stoichiometric coefficients.

ΔH° = 676 kJ

Explanation:

The approximate enthalpy change of the combustion of methane can be obtained by subtracting the enthalpies of the reactants from the products. The combustion of methane is shown using the chemical equation below:

C + 2 ⇔ 2 + C

Therefore, the approximate enthalpy change is:

ΔH° = 2*(Δ) + Δ - Δ - 2*(Δ) = 2(928)+1472-1656-2(498) = 676 kJ

The approximate enthalpy change is 676 kJ.

We used only the magnitude of the enthalpies for the calculation.

a is the answer to this question

explanation:

assuming that your periodic table has eighteen columns, you should highlight   the four elements in the third column from the left of the table.

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the have energy higher than those in the orbital while lower than those of the orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the orbital is therefore filled right after orbitals and before orbitals.  

potassium has electron configuration and calcium . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the and should be highlighted as well.