Asample of an unknown gas has a mass of 0.582g. it's volume is 21.3 ml a a temp of 100 degrees celsius and a pressure of 754 mmhg. determine the molar mass

Molar mass = 0.09 × 10⁴ g/mol

Explanation:

Given data:

Mass = 0.582 g

Volume = 21.3 mL

Temperature = 100°C

Pressure = 754 mmHg

Molar mass = ?

Solution:

(21.3 /1000 = 0.0213 L)

(100+273= 373 K)

(754/760 = 0.99 atm)

PV = nRT

n = PV/RT

n = 0.99 atm × 0.0213 L / 0.0821 atm. L. mol⁻¹. k⁻¹ × 373 K

n =0.02 mol/ 30.6

n = 6.5 × 10⁻⁴ mol

Molar mass = Mass/ number of moles

Molar mass = 0.582 g / 6.5 × 10⁻⁴ mol

Molar mass = 0.09 × 10⁴ g/mol

a is the correct answer

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 :

equation 2 :

equation 3 :

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 :

let us add equation 1 & 4

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol