Copper forms two oxides, Cu2 O and CuO. a. Name these oxides. b. Predict over what temperature r

Copper forms two oxides, Cu2 O and CuO. a. Name these...

Copper forms two oxides, $\mathrm{Cu}_{2} \mathrm{O}$ and $\mathrm{CuO}$. a. Name these oxides. b. Predict over what temperature range this reaction $$\mathrm{Cu}_{2} \mathrm{O}(\mathrm{s}) \rightarrow \mathrm{CuO}(s)+\mathrm{Cu}(s)$$ is spontaneous by using the following thermodynamic data: (FIGURE CAN'T COPY) c. Why is the standard molar entropy of $\mathrm{Cu}_{2} \mathrm{O}(s)$ larger than that of $\mathrm{CuO}(s) ?$

Copper forms two oxides, $\mathrm{Cu}_{2} \mathrm{O}$ and $\mathrm{CuO}$.
a. Name these oxides.
b. Predict over what temperature range this reaction $$\mathrm{Cu}_{2} \mathrm{O}(\mathrm{s}) \rightarrow \mathrm{CuO}(s)+\mathrm{Cu}(s)$$ is spontaneous by using the following thermodynamic data: (FIGURE CAN'T COPY)
c. Why is the standard molar entropy of $\mathrm{Cu}_{2} \mathrm{O}(s)$ larger than that of $\mathrm{CuO}(s) ?$

Key Concepts

Standard Molar Entropy and Structural Effects

This concept relates to the interpretation of standard molar entropy values, which quantify the disorder or randomness at the molecular level. Differences in crystal structures, bonding, and molecular arrangements in solids can lead to variations in entropy. Structural complexities, such as lattice defects or electronic configurations, often cause one solid to exhibit higher entropy than another, even if the chemical composition is similar.

Temperature Dependence of Reaction Spontaneity

This principle examines how the spontaneity of a reaction is influenced by temperature. Since the Gibbs free energy change is a function of temperature through the T?S term, varying the temperature can shift the balance between endothermic or exothermic reactions with different entropy changes, thus expanding or narrowing the temperature range over which a reaction is spontaneous.

Reaction Thermodynamics

This concept involves the study of energy changes accompanying chemical reactions, primarily focusing on the Gibbs free energy change (?G), which determines a reaction’s spontaneity. The relationship ?G = ?H - T?S is utilized to predict whether a reaction will proceed spontaneously under certain conditions, emphasizing the roles of enthalpy (?H) and entropy (?S) in the process.

Chemical Nomenclature for Metal Oxides

This concept addresses how oxides of metals are named based on the oxidation states of the metal ion in the compound. For instance, metals that can exhibit multiple oxidation states will have distinct oxides named accordingly, such as metal(I) oxide and metal(II) oxide. The naming indicates the predominant oxidation state of the metal, which is essential for understanding reactivity, composition, and properties of the oxide.

Transcript

00:01 So for this problem, we're asked a series of questions about the following reaction that i have written at the top of the screen.

00:07 The first is to name the copper oxides.

00:11 So remember that when we're naming transition metals, we write the transition metal, followed by the oxidation state and then oxide, since we're talking about oxygen and ions.

00:27 And so we need to determine the oxidation state of both oxide species.

00:37 In order to do that, we need to calculate the formal charge.

00:43 So for oxygen, it has six valence electrons, and it wants to get to an octet.

00:52 So eight valence electrons.

00:55 So we would subtract eight minus six.

00:59 Excuse me, we subtract the actual number of valence minus the ideal to get minus two.

01:13 So this oxygen has a charge of negative two.

01:17 So we see that these oxide species are not charged, and so we can use that to calculate the oxidation state of the copper.

01:27 So for our reactants, we see we have two copper atoms in our molecules.

01:33 Which must mean that they each have a plus one oxidation state to get to an overall charge of zero.

01:44 So this first is going to be copper one oxide.

01:53 And on our product side, we see we have one copper, which must mean that to balance a charge of negative two, it must have a charge of plus two.

02:03 So that is called copper 2 oxide.

02:14 We're next asked to calculate the temperature over which this reaction is spontaneous.

02:25 So we can do that using the equation delta g equals delta h minus t delta s.

02:39 And then setting delta g equal to zero, we can...

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