You have an evacuated container of fixed volume and known mass and introduce a known mass of a gas sample. measuring the pressure at constant temperature over time, you are surprised to see it slowly dropping. you measure the mass of the gas-filled container and find that the mass is what it should be - gas plus container - and the mass does not change over time, so you do not have a leak. part a suggest an explanation for your observations. suggest an explanation for your observations.
1. the gas undergoes a chemical reaction that has fewer gas particles in products than in reactants. pressure is directly proportional to number of particles, so the pressure decreased.
2. when the gas was plased into container it obtained some extra kinetic energy after some time this energy was expend, so the speed of the particles reduced and the pressure dropped the gas
3. undergoes a chemical reaction that has more gas particles in products than in reactants.
4. pressure is directly proportional to number of mass.

The correct option is

1. The gas undergoes a chemical reaction that has fewer gas particles in products than in reactants. pressure is directly proportional to number of particles, so the pressure decreased.

Explanation:

To solve the question, we note the following

1) The pressure is reducing

2) Volume, mass and temperature is constant

From the combined gas equation we have, P·V = n·R·T which means for a given mass of gas

P₁·V₁ = n·R·T₁ = P₂·V₂ = n·R·T₂ , but the volume and the temperature are both constant, therefore we have

P₁·V₁ = n·R·T₁ = P₂·V₁ = n·R·T₁ and P₂ <  P₁

Where R = constant, then we must have

P₁·V₁ = n₁·R·T₁ = P₂·V₁ = n₂·R·T₁ where n₂ <  n₁

Option 1 is likely

We have by kinetic theory of gases P =

and as such for pressure depends only on the number of moles so option 2 is cancelled out

Option 3 increases the amount n therefore it is not likely and

Option 4 is limited in content.

the answer for sodium is 0.186

the answer for rubidium is 0.251

when the volume of gas is   changed from   717.73 ml   to 852 ml   the temperature will   change   from 315   c to 452   c

    calculation

this is calculated using the charles law formula

that is,   v1/t1 = v2/t2

          v1=?

        t1 = 315 c   into   kelvin = 315 +273 = 588 k

        v2 = 852   ml

        t2 = 425c + 273 =698 k

make v1   the subject of the formula ( by   multiplying both side by t1)

  v1=( v2 xt1) / t2

v1= (852 ml   x 588 k)/ 698 k= 717.73 ml