Which equation is correct - Essay Example

Because, copper has two oxides Copper (I) oxide Cu2O and Copper (II) oxide CuO; therefore, there can be following two possible equations for thermal decomposition of Copper (II) carbonate: It is to be determined as which of the two equations is the correct equation. Looking at the right side of equation, we find the clue for designing an experiment to determine the correct equation of the thermal decomposition. There are two clues – 1. Mass of the black residue and 2. Volume of the gas liberated.

If one starts the thermal decomposition experiment with two moles i.e. 247 grams (2x123.5 grams) of copper carbonate and mass of the black residue is 143 gram, then Equation 1 is correct; on the other hand the mass of black residue being 159 grams implies Equation two being correct. One can measure the volume of the gas released as well. In case of Equation 1 being correct, two moles of copper carbonate will give two and a half moles of carbon dioxide gas, which is 2.5x22.4 liters = 56 liters at STP (Standard Temperature and Pressure, which is 273.

16 K and 1 Atmosphere). In case of Equation 2 being correct, two moles of copper carbonate will give only two moles of gases, which will occupy 44.8 liters at STP. Based on these clues, we design the following experiment to determine the correct equation for thermal decomposition of copper carbonate. Pneumatic trough, test tube (13 x 100 mm), one hole stopper to fit test tube, plastic tube (from pulled Beral), graduated cylinder (100 mL), thermometer, laboratory burner, test tube clamp, CuCO3 (solid), balance 5.

Bubbles started getting into the graduated cylinder. Towards the end of the decomposition reaction the rate of CO2 release slowed down. When the bubbling stopped, the burner and the delivery tube were removed. Because 2.5x10-3 moles of copper nitrate gives 2.5x10-3 moles of carbon dioxide gas, therefore, Equation 2 is the correct equation for decomposition of the copper carbonate.