a 7.337 gram sample of chromium is heated in the presence of excess oxygen. a metal oxide is formed with a mass of 9.595 g. determine
the empirical formula of the metal oxide.

Empirical formula is CrO

We are given;

We are required to determine the empirical formula of the metal oxide.

Mass of oxygen = Mass of the metal oxide - mass of the metal

                          = 9.595 g - 7.337 g

                         = 2.258 g

Moles of chromium metal

Molar mass of chromium = 51.996 g/mol

Moles of Chromium = 7.337 g ÷ 51.996 g/mol

                                 = 0.141 moles

Moles of oxygen

Molar mass of oxygen = 16.0 g/mol

Moles of Oxygen = 2.258 g ÷ 16.0 g/mol

                            = 0.141 moles

Mole ratio of Chromium to Oxygen

          Cr : O

0.141 mol : 0.141 mol

             1 : 1

Empirical formula is the simplest whole number ratio of elements in a compound.

Thus the empirical formula of the metal oxide is CrO

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.