1. Write a balanced chemical equation, including physical state, for the decomposition of solid mercury (II) oxide (HgO) into liquid mercury and gaseous dioxygen.

Question

1. Suppose 28.0 mL of dioxygen gas are produced by this reaction, at a temperature of 80.0*C and pressure of exactly 1 atm. Calculate the mass of mercury(II) oxide that must have reacted. Round your answer to 3 significant digits.

Answer 1

2HgO(s) ==> 2Hg(l) + O₂(g) ... balanced equation

Find moles of O₂:

PV = nRT and n = PV/RT

n = (1atm)(0.028 L)/(0.0821)(353) = 0.000966 moles O₂

moles HgO = 0.00966 mol O₂ x 2 mol HgO/mol O₂ = 0.00193 mol O₂

mass HgO = 0.00193 moles HgO x 217 g/mole = 0.419 grams