For the theoretically perfect reaction 2H² +O²---2H²O if you react 300 molecules pf hydrogen and 200 molecules of oxygen, how many oxygen molecules will you have that do not engage in the reaction? Answer 50, 100, 150, or 200?

You only need 150 moles of O2 to burn up the hydrogen. You will have 50 moles left.

To determine the number of oxygen molecules that do not engage in the reaction, we need to find the stoichiometry of the reaction. According to the balanced equation 2H² + O² -> 2H²O, we can see that 1 molecule of oxygen reacts with 2 molecules of hydrogen to form 2 molecules of water.

Therefore, if we react 300 molecules of hydrogen, we would need 150 molecules of oxygen for a complete reaction (since 2H² = 300 molecules requires O² = 150 molecules).

Since we only have 200 molecules of oxygen, and the reaction only requires 150 molecules, the remaining 50 molecules of oxygen will not engage in the reaction.

Hence, the answer is 50 oxygen molecules.

To determine the number of oxygen molecules that do not engage in the reaction, we need to find the limiting reactant first. The limiting reactant is the reactant that is completely consumed and determines the amount of product that can be formed.

In this case, we have 300 molecules of hydrogen and 200 molecules of oxygen. To find the limiting reactant, we need to compare the ratio of the coefficients of the balanced chemical equation, which in this case is 2:1 for hydrogen to oxygen.

Since the ratio is 2:1, we need twice as many moles of hydrogen as oxygen to react fully. So, for every 2 molecules of hydrogen (H₂), we require 1 molecule of oxygen (O₂). However, we have 300 molecules of hydrogen and 200 molecules of oxygen.

To find the number of oxygen molecules required to react with all 300 molecules of hydrogen, we can use the following calculation:

200 molecules of O₂ * (2 molecules of H₂ / 1 molecule of O₂) = 400 molecules of H₂

Since we have only 300 molecules of H₂ available, the oxygen molecules are in excess. Therefore, none of the oxygen molecules will be left unreacted.

Hence, the correct answer is 0 oxygen molecules will not engage in the reaction.

The answer be 2 fam.