6. The density of sodium chloride is 2.165 g/cm³. Using only the density and crystal structure, calculate the distance between Na and CI atoms in the structure.

Hi, can someone pls tell me if these answers are correct and help me find the answers to the ones I didn't know, thanks ?

4. The common oxidation number for an alkaline earth metal is +2. (a) Using the Born-Mayer equation (for determining the lattice enthalpy) and a Born-Haber cycle (draw it), show that CaCl is an exothermic compound (negative AHf). Make a reasonable prediction to estimate the ionic radius of Ca (explain your reasoning). The sublimation (atomization) enthalpy for Ca(s) is 178 kJ/mol. (b) Show that an explanation for the non-existence of CaCl can be found in the enthalpy change for the reaction below. The AHf for CaCl2(s) is -190.2 kcal/mol. 2 CaCl(s) → Ca(s) + CaCl2(s)

Give TWO reasons why aluminium metal was not commonly used till last century, even though it is one of the most common elements on earth. (b) Why are copper and lithium such important elements today?

If the lead can be extracted with 92.5%% efficiency, what mass of ore is required to make a lead sphere with a 7.50 cmcm radius?

The reaction of barium with sulfur is similar to that of magnesium with sulfur. Write the balanced chemical equation for the reaction of barium with sulfur. Include phase symbols.

Calcium ions contribute to the hardness of water.  a) Based on the Ksp experiment, describe a way to “soften” water by removing calcium ions.  b) what would be the advantages and disadvantages of this method?

21. Based on your understanding of the relationships between the structures and physical properties of elements and compounds, which of the substances (Table 1) is most likely a metallic element? Why? Explain your reasoning in at least two (2) sentences.

Ca^2+ and S^2- as a chemical formula

A 3.00- g sample of an alloy of Pb Lead was dissolved in nitric acid (HNO3). Sulfuric acid was added to this solution, which precipitated 1.69 g of lead sulfate (PbSO4). What is the percentage of lead (Pb) in the sample? (Given the atomic mass of Pb = 207 , S =32, O = 16 )