At standard conditions a helium and nitrogen mixture has density 0.50 g/l. Find the concentration of helium atoms in units of 1 0 19 c m − 3 (two decimals). Use 22.4 l/mol and 2.69 × 1 0 19 molecules/

Question

At standard conditions a helium and nitrogen mixture has density 0.50 g/l. Find the concentration of helium atoms in units of 1 0 19 c m − 3 (two decimals). Use 22.4 l/mol and 2.69 × 1 0 19 molecules/ c m 3 at STP.

TestHub · Accepted Answer

Mean molar mass = 0.50 × 22.4 = 11.2 g. 4 x + 28 ( 1 − x ) = 11.2 gives x = 0.700 . Concentration = 0.700 × 2.69 × 1 0 19 = 1.88 × 1 0 19 c m − 3 .

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