the mass of chemical a is 2 g, and the mass of chemical b is 5 g. if the two chemicals are mixed and a
chemical reaction takes place, what is the mass of the end products?

2 g of A react with 5 g of B. After the chemical reaction takes place, the mass of the end products is 7 g.

Let's consider the following generic reaction.

A + B ⇒ Products

According to Lavoisier's law of conservation of mass, matter is not created nor destroyed over the course of a chemical reaction.

Thus, the mass of the reactants before the reaction must be equal to the mass of the products after the reaction.

2 g of A react with 5 g of B. After the chemical reaction takes place, the mass of the end products is 7 g.

Learn more: link

Explanation:

The Law of Conservation of Mass states that matter cannot be destroyed or created.

That is, the total mass before and after the reaction stays the same.

                  A + B ⟶ C

mass/g:      2    7        x

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.

b.

the accuracy of the data.