Question

A sample that weighs 109.75 g is a mixture of 40% helium atoms and 60% krypton atoms. How many particles are present in the sample?

Answer 1

Answer:7.082*10²⁴

Explanation:Total weight=109.75 g

Weight of helium = 109.75*40/100 = 43.9g

Weight of krypton = 109.75*60/100= 65.85g

1 mole of an element contains 6.022* 10²³atoms/particles

Helium:

1 mole of helium contains 4 grams.

4 grams of helium contains 6.022*10²³ particles.

So 43.9 g helium contains 6.022*10²³*43.9/4 = 6.61*10²⁴ particles

Krypton :

1 mole of krypton contains 84 grams.

84 grams of krypton contains 6.022*10²³ particles.

So 65.85 g krypton contains 6.022" 10²³*65.85/84= 4.72*10²³ particles.

Total number of particles= 6.61*10²⁴+ 4.72*10²³= 7.082*10²⁴