A mixture of CO2 and Kr weighs 41.0 g and exerts a pressure of 0.729 atm in its container. Since Kr is expensive, you wish to recover it from the mixture. After the CO2 is completely removed by absorption with NaOH(s), the pressure in the container is 0.193 atm. (a) How many grams of CO2 were originally present? (b) How many grams of Kr can you recover?

a) 24.31 g

b) 16.69 g

Explanation:

A mixture of CO2 and Kr weighs 41.0 g and exerts a pressure of 0.729 atm in its container.

After the CO2 is completely removed by absorption with NaOH(s), the pressure in the container is 0.193 atm.

Therefore, Pressure of Kr = 0.193 atm

Pressure of CO2  = 0.729 - 0.193 = 0.536 atm

Their mole fraction can be also determined as follows:

CO2 =

CO2 =

= 0.735

Also; for Kr ; we have

Kr =

Kr = 0.265

Molar mass of CO2 = 44 g/mol

Molar mass of Kr = 83.78 g/mol

Mass of CO2 = mole fraction * molar mass = 0.735 * 44 = 32.34

Mass of Kr = 0.265 *  83.78 = 22.20

Total mass = 32.34 +22.20 = 54.54

The Percentage of gas in mixture is  as follows:

% CO2 = * 100 %

= 0.5930

= 59.30%  

(a) Mass of CO2 in mixture = 0.5930* 41 g = 24.31 g

% Kr = * 100 %

= 0.407

= 40.70 %

(b) Mass of Kr in mixture = 0.407 * 41 = 16.69 g

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.

considering the question as per the attachment

here we can see that the radon nuclide has 222 as the atomic mass number and 86 as the atomic number.

when it undergoes nuclear fission it gives polonium which has atomic mass number as 218 and atomic number will be 84 along with a helium nucleus which has 4 atomic mass number and 2 as its atomic number.

222 = 218 + 4 (atomic mass number)

86 = ? + 2; therefore ? = 86-2 = 84.

the atomic mass number of polonium will be 84.