A sample of mercury(II)oxide is placed in a 5.00 L evacuated container and heated until it decomposes entirely to mercury metal and oxygen gas.The container is then cooled to 25°C.One now finds that the gas pressure inside the container is 1.73 atm.What mass of mercury(II)oxide was originally placed into the container?
A)1.51 g
B)45.6g
C)76.6 g
D)913 g
E)153 g

Question

Quizplus · Accepted Answer

Using the ideal gas law, PV = nRT, we can calculate the moles of oxygen gas produced. With P = 1.73 atm, V = 5.00 L, R = 0.0821 L·atm/mol·K, and T = 298 K, we find n = 0.353 mol of O2. Since the decomposition of HgO produces O2 in a 2:1 ratio, 0.706 mol of HgO was decomposed. The molar mass of HgO is 216.59 g/mol, so the mass of HgO is 0.706 mol × 216.59 g/mol = 153 g.

A Sample of Mercury(II)oxide Is Placed in a 5