# Experiment: To determine the correct equation for the decomposition

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Introduction

Experiment: To determine the correct equation for the decomposition of copper carbonate Introduction and background information: Important points to note: 'At room temperature, 25�C and atmospheric pressure at 1 atmosphere, I mole of any gas will occupy a volume of 24 dm�.' We will need this to work out how much copper carbonate to decompose to obtain a sufficient amount of carbon dioxide gas. To work out the amount of copper carbonate to use I will need to use the following equations: Number of moles = Mass / Mr PV = nRT P = Pressure V = Volume n = Number of moles R = Gas constant T = Temperature We can substitute n (number of moles) with the first equation to get: PV = (mass/Mr) x RT When rearranged this gives: Mass = (Mr x PV) / RT This will allow me to work out the mass needed. Aim: The aim of this experiment is to determine which of the following equations is correct: Equation 1: 2CuCO3 (s) ...read more.

Middle

* The apparatus used should be totally air tight so no gas can escape. * Try to make sure that there are no bubbles of gas in the measuring cylinder full of water before starting the experiment. * Always measure from the bottom of the meniscus. Calculations and method: Using the first equation: 2CuCO3 (s) Cu2O (s) + 2CO2 (g) + 1/2 O2 (g) Molar ratio: 2 1 + 2 + 1/2 Using 1 gram of copper carbonate: Number of moles = Mass / Mr = 1 / 123.5 = 8.097 x 10� moles copper carbonate Because the molar ratio between the copper carbonate and the gas is 2 : 2 1/2, the number of moles of gas produced = 8.097 x 10� moles x 1.25 = 1.012 x 104 moles Volume of gas produced = number of moles x 24 dm� = (1.012 x 104) x 24 = 2.429 x 105 dm� (242.91 cm�) Therefore, if 1 gram of 2 molar copper carbonate is to be used, approximately 242.91 cm� of gas should be produced. ...read more.

Conclusion

5. Fix the boiling tube into the clamp and make sure that the delivery tube is directly underneath the measuring cylinder. 6. Heat the copper carbonate until it has turned black in colour and the volume of gas in the measuring cylinder has stopped moving. 7. Measure and note down the volume of gas produced. 8. Repeat the procedure to get another set of results. 9. Repeat the entire experiment but replace the 1 molar copper carbonate with 2 molar copper carbonate and record the volume of gas produced. (I could have used a gas syringe instead of the upturned measuring cylinder in a water bath. This would have been a lot more accurate. However, I am not experienced with using a gas syringe and accuracy is not entirely essential in this experiment as the volumes of gas that are expected to be obtained have a large difference between them therefore allowing room for error.) After carrying out the experiment I can compare the volumes of gas given off from using different molars of copper carbonate and therefore decide which equation is correct. ...read more.

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