Calculate the δ h°rxn for the decomposition of calcium carbonate to calcium oxide and carbon dioxide. δ h°f [caco3(s)] = –1206.9 kj/mol; δ h°f [cao(s)] = –635.1 kj/mol; δ h°f [co2(g)] = –393.5 kj/mol

Explanation

The formula for calculating the enthalpy change of a reaction by using the enthalpies of formation of reactants and products is

                         CaCO₃(s) ⟶ CaO(s) + CO₂(g)

ΔH°f/kJ·mol⁻¹:    -1206.9         -635.1    -393.5

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the answer for sodium is 0.186

the answer for rubidium is 0.251

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.