A student is performing an experiment in the laboratory to determine the oxidation of copper (Cu). Cu reacts with oxygen in the air to form CuO in the following reaction: Cu (s) + O2 (g) → CuO (s) The student weighted 1.528 g of Cu (s) powder in a crucible and heated the sample with a Bunsen burner. Even by using the Cu in powder form and heating the sample there is unreacted Cu left in the crucible. After heating the student weighted the substance inside the crucible to be 3.647 g. 1. Calculations: a. Balance the chemical equation for the reaction of Cu with oxygen. b. Using the balanced chemical equation, calculate the theoretical yield of copper oxide (CuO). c. If the student weighted 3.647 g of substance in the crucible. Calculate how much of this is unreacted Cu (s) and how much is CuO (s). (Hint: use the balanced chemical equation). d. Once you know the amount of CuO (s) obtained in this experiment, calculate the percent yield of CuO in this experiment.
Thermochemistry
Thermochemistry can be considered as a branch of thermodynamics that deals with the connections between warmth, work, and various types of energy, formed because of different synthetic and actual cycles. Thermochemistry describes the energy changes that occur as a result of reactions or chemical changes in a substance.
Exergonic Reaction
The term exergonic is derived from the Greek word in which ‘ergon’ means work and exergonic means ‘work outside’. Exergonic reactions releases work energy. Exergonic reactions are different from exothermic reactions, the one that releases only heat energy during the course of the reaction. So, exothermic reaction is one type of exergonic reaction. Exergonic reaction releases work energy in different forms like heat, light or sound. For example, a glow stick releases light making that an exergonic reaction and not an exothermic reaction since no heat is released. Even endothermic reactions at very high temperature are exergonic.
A student is performing an experiment in the laboratory to determine the oxidation of copper (Cu). Cu reacts with oxygen in the air to form CuO in the following reaction:
Cu (s) + O2 (g) → CuO (s)
The student weighted 1.528 g of Cu (s) powder in a crucible and heated the sample with a Bunsen burner. Even by using the Cu in powder form and heating the sample there is unreacted Cu left in the crucible. After heating the student weighted the substance inside the crucible to be 3.647 g.
1. Calculations:
a. Balance the chemical equation for the reaction of Cu with oxygen.
b. Using the balanced chemical equation, calculate the theoretical yield of copper oxide (CuO).
c. If the student weighted 3.647 g of substance in the crucible. Calculate how much of this is unreacted Cu (s) and how much is CuO (s). (Hint: use the balanced chemical equation).
d. Once you know the amount of CuO (s) obtained in this experiment, calculate the percent yield of CuO in this experiment.
Using your observations and results answer the following questions.
a. What is a crucible?
b. Explain the physical state, (s) and (g), of each substance in the reaction.
c. One student weighed 1.200 g of Cu powder into a crucible and heated it to produce CuO. He was able to obtain only a 15.5% yield. What was the total mass of the crucible contents (CuO plus unreacted Cu)?
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