Answer:
78 g of potassium
Explanation:
According to Lavoisier's Law, the sum of the mass of the products must be equal to the sum of the mass of the reactants.
On the reaction we have potassium oxide as product (K2O) and as reactants potassium (K) and Oxygen (O2)
Having sayin this, the reaction must be as follows:
K + O2 -> K2O
We need to balance the equation to have the same amount of molecules of each element in each side:
4K + O2 -> 2K2O
Taking into account the molar mass of each compound, the reaction can also be written:
4(39g/mol) + 1(32g/mol) -> 2(94g/mol)
solving the multiplications we have that:
156g of K + 32g of O2 -> 188g of K2O
therefore, we need 78 g of K to obtain 94 g of K2O with 16g of O2
