G of potassium reacts with 16 g of oxygen to produce 94 g of potassium oxide

78g

Explanation:

Given parameters:

Mass of oxygen gas = 16g

Mass of potassium oxide = 94g

Unknown:

Mass of reacting potassium = ?

Solution:

To solve this problem, we need to obtain a balanced reaction equation. Then determine the number of moles of the reactant and use it to find that of the other one.

Balanced equation:

                      4K +   O₂   →    2K₂O

  Number of moles of reacting oxygen;

       Number of moles =

molar mass of  O₂ = 2 x 16 = 32g/mole

     Number of moles =  = 0.5mole

From the reaction equation;

          4 mole of K reacted with 1 mole of O₂;

           x mole of K will react with 0.5 mole of O₂

Therefore, 4 x 0.5 = 2 moles of potassium.

Mass of potassium = number of moles x molar mass

              Molar mass of potassium = 39g

Mass of potassium = 2 x 39 = 78g

a small object of mass 3.66 g and charge -17.6 µc is suspended motionless above the ground when immersed in a uniform electric field perpendicular to the ground. what are the magnitude and direction of the electric field?

answer would be letter choice (a),   a ball resting on a shelf. would be another example of potential energy   >   stored energy > not moving.

a ball spinning on a finger   >   kinetic energy > moving energy

a ball rolling on the ground   >   kinetic energy   > moving energy

a   ball flying through the air   > kinetic energy   >   moving energy

hope that                                         : )