Using the following reaction (depicted using molecular models), large quantities of ammonia are burned in the presence of a platinum catalyst to give nitric oxide as the first step in the preparation of nitric acid. Suppose a vessel contains 7.50 g of NH3, how many grams of O2 are needed for a complete reaction?4 NH3 + 5 O2 > 4 NO + 6 H2O

17.65 grams of O2 are needed for a complete reaction.

Explanation:

You know the reaction:

4 NH₃ + 5 O₂ --------> 4 NO + 6 H₂O

First you must know the mass that reacts by stoichiometry of the reaction (that is, the relationship between the amount of reagents and products in a chemical reaction). For that you must first know the reacting mass of each compound. You know the values of the atomic mass of each element that form the compounds:

So, the molar mass of the compounds in the reaction is:

By stoichiometry, they react and occur in moles:

Then in mass, by stoichiomatry they react and occur:

Now to calculate the necessary mass of O₂ for a complete reaction, the rule of three is applied as follows: if by stoichiometry 68 g of NH₃ react with 160 g of O₂, 7.5 g of NH₃ with how many grams of O₂ will it react?

mass of O₂≅17.65 g

17.65 grams of O2 are needed for a complete reaction.

nuclear fission produces elements that are heavier than helium.

the elements that are used in nuclear fission and their products are much heavier than helium.