How much does 12 liters of ammonia weighs at room temperature and pressure (293k and 100 kpa)?

8.38g

Explanation:

Given parameters:

Volume of the gas = 12L or 12dm³

Temperature = 293k

Pressure = 100kPa

Unknown: mass of the ammonia gas = ?

_____ Now let us take the unit of pressure to atm:

    Pressure = 100 kPa

    1kPa = 0.00986923atm

    100kPa = 100 x 0.00986923 = 0.987atm

Solution:

From the ideal gas law, we can find the number of moles of the ammonia gas. Using the number of moles, it would be possible to find the mass of the ammonia.

                  PV = nRT

                    n =

Where R is the gas constant and its value is 0.082atmdm³mol⁻¹K⁻¹

      n =

     n = 0.493mol

We know that, mass = number of moles x molar mass

Molar mass of NH₃ = 14 + (3x1) = 17gmol⁻¹

                    mass of NH₃ = 0.493 x 17 = 8.38g

part 1: the half-life of the element is 22 years.

part 2: it will take 132.02 year for the sample to decay from 308.0 g to 4.8125 g.

explanation:

part 1: there are two ways to determine the half life time.

first way: the half life time can be determined directly from its definition as it is the time required for the sample to decay to its half concentration.

from the data the initial concentration was 45.0 g and decayed to its half value (22.5 g) in 22.0 years.

second way: the radio active decay is considered first order reaction so we can use the laws of first order reactions.

k = (1/t) ln (a/a-x), where k is the rate constant of the reaction,

t is the time of the reaction

a is the initial concentration of the reactant

a-x is the remaining concentration at time (t)

a = 45.0 g the initial concentration at t = 0 year.

at t = 22 year, a-x = 22.5 g

then k = (1/22 year) ln (45.0 g/ 22.5 g) = 0.0315 year-1.

the half-life time (t1/2) = ln 2/ k = 0.693/ k =0.693/ 0.0315 = 22 years.

part 2:

using the same law k = (1/t) ln (a/a-x),

using the given data; a = 308.0 g and a-x = 4.8125 g and the calculated k from the part 1 (k = 0.0315 year-1)

t = (1/k) ln (a/a-x) = (1/0.0315) ln (308.0/ 4.8125) = 132.02 years

i dont know

explanation: