Chem Help! Limiting and excess reagent?

Identify the limiting and excess reagent for each of the following scenarios involving the formation of silicone dioxide, SiO2. Please explain!!! Thank you!

Si + O2 --> SiO2

a. 2 atoms of silicone and 2 molecules of oxygen gas
b. 28.1 g of silicone and 48.0 g of oxygen gas
c. 6 mol of silicone and 2 mol of oxygen gas

To identify the limiting and excess reagent, we need to compare the number of moles or the mass (in grams) of each reactant to the stoichiometry of the balanced chemical equation.

a. 2 atoms of silicon and 2 molecules of oxygen gas:
In this case, we need to convert atoms to moles to make a comparison. Since there are 6.022 x 10^23 atoms in 1 mole, we can calculate the number of moles of silicon as follows:
2 atoms Si * (1 mol Si / 6.022 x 10^23 atoms Si) = 3.32 x 10^-24 mol Si

Similarly, we need to convert molecules of oxygen gas to moles. There are 6.022 x 10^23 molecules in 1 mole of gas, so:
2 molecules O2 * (1 mol O2 / 6.022 x 10^23 molecules O2) = 3.32 x 10^-24 mol O2

Since both reactants have the same number of moles, there is an equivalent amount of each. Hence, neither the silicon nor the oxygen gas is the limiting or excess reagent in this scenario.

b. 28.1 g of silicon and 48.0 g of oxygen gas:
We need to convert the masses to moles of each reactant. The molar mass of silicon is 28.1 g/mol, so:
28.1 g Si * (1 mol Si / 28.1 g Si) = 1 mol Si

For oxygen gas, the molar mass is 32.0 g/mol (16.0 g/mol per O atom):
48.0 g O2 * (1 mol O2 / 32.0 g O2) = 1.5 mol O2

Comparing the moles, we find that there is an equal amount of silicon and oxygen gas, so neither the silicon nor the oxygen gas is the limiting or excess reagent in this scenario.

c. 6 mol of silicon and 2 mol of oxygen gas:
For this scenario, we already have the number of moles for each reactant. Looking at the balanced equation, we can see that the ratio between silicon and oxygen gas is 1:1. Thus, when there is an equal ratio of both reactants, neither the silicon nor the oxygen gas is the limiting or excess reagent.

In all three scenarios, neither the silicon nor the oxygen gas is the limiting or excess reagent because the reactants are in an equivalent proportion to each other based on the stoichiometry of the balanced chemical equation.