Question

Silver (I) oxide (Ag_2O) decomposes completely at temperatures in excess of 300 degree C to produce metallic silver and oxygen gas. When 1.6 grams of impure Ag_2O is decomposed and allowed to cool to STP, the reaction is found to yield 72.1 mL of oxygen gas. What is the percentage of Ag_2O in the original impure sample 93.3% 85.5% 44.5% 23.3%

Answer 1

m = 1.6 g of Ag2O

V = 72.1 ml of O2

find mol of O2

n = (PV)/(RT) = 1*(72.1/1000)/(0.082*273) = 0.00322076297 mol of O2

then expect:

2Ag2O --> 4Ag + O2

ratio is 1:2

0.00322076297*2 = 0.00644152594 mol of Ag2O

mass = mol*MW = 0.00644152594*231.735 = 1.49272 g of Ag2O

mass of sample:

% = 1.49272/1.6 *100 = 93.295

a is the answer