Period Table & Energy Random Retrieval

Which of these reactions can be reversed by changing the conditions in a typical advanced chemistry laboratory?

(i) CuSO₄.5H₂O_(s) -> CuSO_4(s) + 5H₂O(l)

(ii) 2Mg_(s) + O_2(g) -> 2MgO_(s)

(iii) NH_3(g) + HCl_(g) -> NH₄Cl_(s)

(iv) CH_4(g) + 2O_2(g) -> CO_2(g) + 2H₂O_(l)

Using enthalpies of formation Δ_fH, calculate the enthalpy change for the following reaction.

2NaHCO_3(s) => Na₂CO_3(s) + H₂O_(l) + CO_2(g)

Select the data from the 'Selection of Enthalpies of Formation and Combustion' shown above.

If this question was generated from Random Retrieval, this data can also be found in TOOLS>Data Sheets.

Calculate the enthalpy change for the formation of one mole of hydrogen chloride gas from its elements given these average bond enthalpies: H-H bond enthalpy = 435 kJ mol^-1, Cl-Cl bond enthalpy = 243 kJ mol^-1 and H-Cl bond enthalpy = 432 kJ mol^-1

Calculate the value of the standard enthalpy change of formation of methane given that the values for standard enthalpy changes of combustion are -890 kJ mol^-1 for methane, -393 kJ mol^-1 for carbon and -286 kJ mol^-1 for hydrogen gas.

Which of the following increase from left to right across the series F₂ - Cl₂ - Br₂?

(i) covalent radius of the atoms

(ii) electronegativitiy

(iii) boiling point

(iv) strength as an oxidising agent

The oxidising agent used to extract bromine from sea water in a displacement reaction is:

Which of these ions has the greatest polarising power?

What is the oxidation number of CARBON in

CH₄

In which of these pairs do both entities have the same electron configuration?

(i) Li and Na

(ii) Na⁺ and Mg²⁺

(iii) F^- and Cl^-

(iv) Cl^- and Ar

An element which consists of a giant structure of atoms held together by covalent bonding is: