Calculate the boiling point of a solution prepared by adding 11.5 g naphthalene (C10H8) to 250.0 g of benzene. Naphthalene is a non-electrolyte solute, and benzene is an organic solvent that exhibits a boiling point of 80.10 oC, and has a kb

81.0°C

Explanation:

Kb benzene = 2.5°C/m

The addition of a solute to a pure solvent produce an elevation in boiling point regarding to boiling point of pure solvent. This phenomenon follows the equation:

ΔT = Kb×m×i

where ΔT represents the increasing in boiling point, Kb is the elevation boiling point constant of the solvent (2.5°C/m for benzene), m is molality of solution (Moles solute / kg solvent) and i is Van't Hoff factor (1 for a non-electrolyte solute as naphthalene).

Moles of 11.5g of naphthalene (Molar mass: 128.17g/mol) are:

11.5g × (1mol / 128.17g) = 0.0897 moles of naphthalene in 250.0g = 0.250kg of benzene.

Molality is:

0.0897 moles of naphthalene / 0.250kg of benzene = 0.359m

Replacing in the equation:

ΔT = Kb×m×i

ΔT = 2.5°C/m×0.359m×1

ΔT = 0.90°C

That means the solution prepared has an elevation in boiling point of 0.90°C. As boiling point of pure benzene is 80.10°C, boiling point of the solution is:

80.10°C + 0.90°C =

alkaline metals are lithium, sodium, rubidium, potassium, cesium and francium.

alkali metals have electronegativity from 0.7 to 1, lowest in periodic table of elements, which means that alkali metals (i group in periodic table) has positive oxidation number in compounds.

electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

alkaline metals (far left in main group) have lowest ionizations energy and easy remove valence electrons,

for example, potassium is the alkali metal and has a single valence electron in the outer electron shell.

electron configuration of potassium is: ₁₉k 1s²2s²2p⁶3s²3p⁶4s¹.

they can not exist alone in nature, because they are very reactive.

it would be d. henry moseley

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