Chemistry, 23.12.2019 18:31 22MadisonT

Asample of he gas (2.0 mmol) effused through a pinhole in 53 s. the same amount of an unknown gas, under the same conditions, effused through the pinhole in 248 s. the molecular mass of the unknown gas is g/mol.

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Answer from: mikey3882

Molecular mass of unknown gas is 87.58 grams per mol.

Explanation:

Let x be the molecular mass of the unknown gas.

Rate of effusion of a gas and its molecular mass is related as:

r ∝ $\frac{1}{\sqrt{M} }$

where r is rate and M is molecular mass.

Molecular mass of He gas = 4 g/mol

Given: Same amount of gas is effused and at same conditions.

Let us say V mL of gas effused.

Then rate = V/t where t is time taken for effusion.

$t_{He}=53\ s\\t_{unknown\ gas}=248\ s$

$r=\frac{V}{t}=\frac{k}{\sqrt{M} }$

Since same amount of gases are effused V doesn't matter.

We can say:

t ∝ √M ⇒

then

$\frac{53}{248}=\frac{\sqrt{4} }{\sqrt{x} }\\x=87.58\ g\ per\ mol$

Hence molecular mass of unknown gas is 87.58 grams per mol.

Answer from: Quest

water molecules stay close to each other through cohesion, the collective action of hydrogen bonds between water molecules. cohesion plants draw water upwards from the root through the stem's transport tubes (xylem) to the leaf. this transport occurs even in large trees and against gravity. transpiration, evaporation of water from plant leaves, creates a tension on water molecules being pulled up from the stem and roots.

water also has high (the attraction of one substance to another) properties because of its polar nature. adhesion of water molecules to plant cell walls counteract gravity while water is transported from roots to leaves.

water exhibits a very high surface tension when compared to other liquids. surface tension is a property of a liquid that holds the surface together and allows it to resist an external force. by capillary action, the water forms concave menisci inside the pores. the high surface tension of water pulls the concavity outwards, generating enough force to lift water from the roots to the leaves of plants.

thus, cohesion, along with adhesion and surface tension creates a capillary action that keeps water molecules interacting and moving through the plants out to the leaf cells.

therefore, option d) is the correct answer.

explanation:

Answer from: Quest

quartz

explanation:

Which of these is not a commonly mined metallic substance?

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Asample of he gas (2.0 mmol) effused through a pinhole in 53 s. the same amount of an unknown gas, u...