When rubidium metal is exposed to air, two atoms of rubidium, Rb, combine with one atom
of oxygen. If 1.98 grams of rubidium is exposed to air, what will be the mass of the product
in grams

2.1653 g

Explanation:

The molar mass of Rubidium is;

85.468 g/mol

Therefore the moles of Rubidium that reacted with oxygen is;

1.98 / 85.468

= 0.0232 moles

If every two moles of Rubidium reacts with one mole of oxygen then the amount of oxygen consumed in the chemical reaction is;

0.5 * 0.0232

= 0.0116 moles

The molar mass of an oxygen atom is 16 g/mole. Then the amount of O in grams consumed is;

0.0116 * 16

=0.1853 g

The final weight of the Rubidium II Oxide is;

1.98 + 0.1853

= 2.1653 g

the atomic number will stay the same no matter how many electrons it has, so it doesn’t decrease nor increase. it’ll only change with a different number of protons