Question

What is the molecular mass and compound formula for potassium and oxygen?

A. Molecular Mass: 56.1 g/mol, Formula: K2O
B. Molecular Mass: 36.5 g/mol, Formula: KO
C. Molecular Mass: 64.1 g/mol, Formula: K2O2
D. Molecular Mass: 45.0 g/mol, Formula: KO2

Answer 1

The correct molecular mass and formula for a compound of potassium and oxygen is 94.2 g/mol and K2O, respectively, because potassium forms K+ ions and oxygen forms O2- ions.

Step-by-step explanation:

The molecular mass and compound formula for a compound composed of potassium (K) and oxygen (O) can be determined using the respective atomic masses and ionic charges. Potassium has an atomic mass of 39.10 g/mol and forms a K+ ion, while oxygen has an atomic mass of 15.999 g/mol and forms an O2- ion. Using the crisscross method for constructing the formula of an ionic compound, we can deduce that two K+ ions will combine with one O2- ion to form K2O. The molar mass of K2O is calculated by adding (2 × 39.10 g) + 15.999 g, which equals 94.199 g/mol. Therefore, the correct answer is A. Molecular Mass: 94.2 g/mol, Formula: K2O.