A gas of unknown molecular mass was allowed to effuse through a small opening under constant pressure conditions. It required 57 s for 1.0 L of the gas to effuse. Under identical experimental conditions it required 32 s for 1.0 L of O2 gas to effuse. Calculate the molar mass of the unknown gas. (Remember that the faster the rate of effusion, the shorter the time required for effusion of 1.0 L; that is, rate and time are inversely proportional.)

101.59 g/mol

Explanation:

Unknown gas = X

Using grahms's law of effusion;

RateX / RateO2  = √ (Molar massO2 / Molar massX)

RateX= Volume / time = 1 / 57 = 0.01754

RateO2 = Volume / Time = 1 / 32 = 0.03125

Molar massO2 = 32

Inserting the values into the equation;

0.01754 / 0.03125  =  √ (32 / Molar massX)

0.56128² = 32 / Molar massX

0.3150 * Molar massX = 32

Molar massX = 32 / 0.3150

Molar massX = 101.59 g/mol

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.