When does a change in energy occur?

A gas has density 2.41 g/liter at 25°C and 770 mm Hg. Calculate it's molecular mass (R = 0.0821 L atm.mol-1K-1

Evgesh-ka [11]

Answer:

Explanation:

Given : Density - 2.41 g/liter

Temperature - 25° C

Pressure : 770 mm Hg

R = 0.0821 L atm mol-¹K-¹

Find : Molecular mass of gas

Solution : Ideal gas equation with respect to density will be : PM = dRT. In the formula, P is pressure, M is molecular mass, d is density, R is gas constant and T is temperature.

Keeping the values in equation-

Pressure : 770 mm Hg = 1 atm

Temperature : 273 + 25 = 298 K

M = dRT/P

M = (2.41*0.0821*298)/1

M = 58.96 gram/mol

Thus, the molecular mass of gas is 58.96 gram/mol.

8 0

3 years ago

The absorbance of an equilibrium mixture containing FeSCN2 was measured at 447 nm and found to be 0.347. What is the equilibrium

Ksenya-84 [330]

Answer:

The concentration is $C = 1.11 mol/L$

Explanation:

From the question we are told that

The absorbance is $A = 0.347$

The length is $l = 447 nm = 447 *10^{-7} \ cm$

Generally absorbance is mathematically represented as

$A = \epsilon* C * l$

where $\epsilon$ is the molar absorptivity of FeSCN2 with a value $\epsilon = 7.0*10^3 L/cm/mol$

and $C$ is the equilibrium concentration of FeSCN2

So

$C = \frac{A}{\epsilon * l }$

substituting values

$C = \frac{0.347}{7.0*10^{3} * 447 *10^{-7} }$

$C = 1.11 mol/L$

5 0

2 years ago

When the molecules of gases are heated, the average kinetic energy of the molecules increases,

serious [3.7K]

True is the answer to this

6 0

3 years ago

The SI unit of weight is the same as that of force. What does this tell us about weight? Explain.

masya89 [10]

Answer:

It shows that weight is a form of force.

Explanation:

Basically, weight is the force exerted by your mass multiplied by the gravitational acceleration of the place you're standing in.

5 0

3 years ago

Nitrogen effuses through a pinhole 1.7 times as fast as another gaseous element under the same conditions. Estimate the other el

marysya [2.9K]

Answer:

80.92, Krypton

Explanation:

What is effusion?

• It is a process where gas escapes through a pinhole (a very small hole) into a region of low pressure or vacuum

Graham's law of effusion of gas

• states that at a given constant temperature and pressure, the rate of effusion of gases is inversely proportional to the square root of their molar masses

$\boxed{ \frac{Rate_1}{Rate_2} = \sqrt{ \frac{M_2}{M_1} } }$

Calculations

Nitrogen exist as N₂ at room temperature, thus its molar mass is 2(14)= 28.

Let the rate and molar mass of unknown gas be Rate₂ and M₂ respectively.

Since N₂ effuses 1.7 times as fast as the unknown gas,

Rate₁= 1.7(Rate₂)

$\frac{Rate_1}{Rate_2} = 1.7$

$1. 7 = \sqrt{ \frac{M_2}{28} }$

Square both sides:

$2.89 = \frac{M_2}{28}$

Multiply both sides by 28:

2.89(28)= M₂

M₂= 80.92

Identity of gas

The molar mass of 80.92 lies between Bromine and Krypton. However since Bromine exist as Br₂, the value of it's molar mass would be 159.8 instead. Hence, Bromine is eliminated.

If the gas is a diatomic element, the atomic weight is 80.92 ÷2= 40.46. Thus, we are now considering if Argon could be its identity. However, Argon is a noble gas and will not exist as a diatomic element. Argon is therefore eliminated too.

Thus based on the above reasoning, its probable identity is Krypton.

7 0

2 years ago