The formula cuso4 corresponds to \(\mathrm{CuSO_4}\), a common ionic compound in general chemistry that contains the polyatomic sulfate ion.
Key identification: \(\mathrm{CuSO_4}\) is copper(II) sulfate, composed of \(\mathrm{Cu^{2+}}\) and \(\mathrm{SO_4^{2-}}\).
Step 1: Interpret the chemical formula \(\mathrm{CuSO_4}\)
The formula has two parts:
- \(\mathrm{Cu}\): the element copper
- \(\mathrm{SO_4}\): the polyatomic ion sulfate
Sulfate is treated as a single unit in ionic naming and charge accounting.
Step 2: Determine ion charges and the oxidation state of copper
The sulfate ion has a well-known charge of \(-2\):
\[ \mathrm{SO_4^{2-}} \]
Ionic compounds are neutral overall, so the copper ion must supply a \(+2\) charge to balance sulfate:
\[ (+2) + (-2) = 0 \quad \Rightarrow \quad \mathrm{Cu^{2+}} \]
Therefore, copper has oxidation state \(+2\) in \(\mathrm{CuSO_4}\).
Step 3: Write the correct name
Copper is a transition metal with more than one common ionic charge, so the Stock system uses a Roman numeral to show the charge:
- \(\mathrm{Cu^{2+}}\) is copper(II)
- \(\mathrm{SO_4^{2-}}\) is sulfate
The name is copper(II) sulfate.
Step 4: Write the dissociation equation (common aqueous chemistry use)
In water, copper(II) sulfate dissociates into ions:
\[ \mathrm{CuSO_4(s) \rightarrow Cu^{2+}(aq) + SO_4^{2-}(aq)} \]
Step 5: Compute the molar mass of \(\mathrm{CuSO_4}\)
Add the atomic masses of one copper, one sulfur, and four oxygens. Using typical periodic table values \(M(\mathrm{Cu}) = 63.55\ \text{g/mol}\), \(M(\mathrm{S}) = 32.07\ \text{g/mol}\), \(M(\mathrm{O}) = 16.00\ \text{g/mol}\):
\[ M(\mathrm{CuSO_4}) = 63.55 + 32.07 + 4 \cdot 16.00 = 63.55 + 32.07 + 64.00 = 159.62\ \text{g/mol} \]
| Component | Count | Atomic mass (g/mol) | Contribution (g/mol) |
|---|---|---|---|
| Copper (Cu) | \(1\) | \(63.55\) | \(1 \cdot 63.55 = 63.55\) |
| Sulfur (S) | \(1\) | \(32.07\) | \(1 \cdot 32.07 = 32.07\) |
| Oxygen (O) | \(4\) | \(16.00\) | \(4 \cdot 16.00 = 64.00\) |
| Total | \(159.62\ \text{g/mol}\) |
Common clarification: hydrates vs anhydrous \(\mathrm{CuSO_4}\)
The formula \(\mathrm{CuSO_4}\) refers to the anhydrous salt. A frequently encountered hydrated form is copper(II) sulfate pentahydrate, \(\mathrm{CuSO_4\cdot 5H_2O}\), which has additional mass from water molecules and is named separately.