The equivalent mass of copper is 31.75 g eq⁻¹.
Understanding Equivalent Mass
Equivalent mass is a concept used in chemistry to describe the mass of a substance that will react with or displace a fixed quantity of another substance. This fixed quantity is often defined as one mole of hydrogen ions (H⁺) or its equivalent. The equivalent mass isn't constant for a given element and depends on the specific reaction it undergoes.
Calculation of Equivalent Mass
The equivalent mass is calculated by dividing the molar mass of the substance by its n-factor (valency or number of electrons transferred per mole). In the context of copper, which can have varying valencies, the specific reaction must be specified.
Copper and Its Common Valencies
Copper commonly exists in two oxidation states: Cu⁺ (cuprous) and Cu²⁺ (cupric). For the equivalent mass stated in the reference (31.75 g eq⁻¹), it implicitly assumes the reaction where copper is in its +2 oxidation state, often observed in copper salts.
Example: Copper(II) Reactions
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Reaction with acids: When copper(II) ions are involved, the n-factor is 2. Consider a typical reaction where copper(II) ions are formed. For instance, in the formation of CuSO₄.
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Calculation: Given the molar mass of copper is approximately 63.5 g/mol, and copper in this case has a valency of 2 (Cu²⁺), the equivalent mass can be calculated as follows:
Equivalent mass = (Molar mass of Copper) / (Valency)
Equivalent mass = 63.5 g/mol / 2
Equivalent mass = 31.75 g eq⁻¹This matches the information provided in the reference: "Equivalent mass of Copper = 63.52=31.75geq−1".
Table: Equivalent Mass
| Element | Molar Mass (g/mol) | Common Valencies | Equivalent Mass (g eq⁻¹) |
|---|---|---|---|
| Copper | 63.5 | +1, +2 | 31.75* |
- This is the equivalent mass assuming Copper(II) oxidation state and is based on the reference.
Practical Insights
- Equivalent mass is critical in stoichiometric calculations, particularly in titrations and electrochemical reactions.
- It simplifies the calculations by providing a direct relation between the amount of reacting substances based on their reactive capacity.
- Understanding that the equivalent mass can change based on the reaction is critical when performing calculations in complex reactions.
