Question

The experiment this is in reference to is the determination of molar mass of a metal. a piece of magnesium ribbon was dangled on a copper wire into a tube with tap water and hydrochloric acid then placed into a beaker of water that was at room temperature.

Questions 1. Practice: Oxygen can be generated by thermal decomposition of potassium chlorate: 2 KClO3 (s) —> 2 KCl (s) + 3 O2 (g) Calculate the volume of oxygen (in liters) produced at 27°C and 742 Torr by the decomposition of 1.23 g of potassium chlorate. 2. How would your experimental value for the molar mass compare to the true value (too high or too low) if you accidentally measured the gas volume before all of the metal reacted? Explain.

Answer 1

1) Equation: 2Kag, → 2C1 + 30, No of moles of KCIO, decomposed = 1.23g x- 220 x 1mol KCIO 53* 122.55 g = 0.01004 mol KCIO, Amount of O, produced = 0.01004 mol KCIO,x= 3 mol O2 $2 mol KCIO, = 0.01506 mol O2 Volume of the O, gas produced = *-* (0.01506 mol)( 62.4 k. Por ) (27° C+273)K (0.01506 mol)( 62.4 . ) (300K) 742 torr 742 torr = 0.380 L