Question

If you have 15.0 g Na, how many grams of O2 are required for reaction?

Answer 1

STEP I : BALANCED EQUATION AND MOLES OF Na

2Na_(s) + O_2(g) $\to$ 2Na2O_(s)

Moles of Na in 15.0g $= \dfrac{mass}{RAM} = \dfrac{15.0g}{23g/mol}$

$=0.652moles$

STEP II : MOLES AND MASS OF O₂

From the equation, mole ratio of Na:O₂ = 1:1

Moles of oxygen $=\dfrac{1}{2}x0.652mol = 0.326moles$

Mass of oxygen = Moles x Molar Mass

= 0.326mol x 16g/mol

= 5.22g

Mass of oxygen