Write a formula for each ionic compound. (a) copper(I) chlorate (b) potassium permanganate (c) lead(II) chromate (d) calcium fluoride (e) iron(II) phosphate (f) lithium hydrogen sulfite
The Correct Answer and Explanation is:
Here are the formulas for each of the ionic compounds:
(a) Copper(I) chlorate
- Copper(I) has a charge of +1, and chlorate (ClO₃⁻) has a charge of -1.
- To balance the charges, the formula is CuClO₃.
(b) Potassium permanganate
- Potassium (K⁺) has a charge of +1, and permanganate (MnO₄⁻) has a charge of -1.
- Since the charges are balanced, the formula is simply KMnO₄.
(c) Lead(II) chromate
- Lead(II) has a charge of +2, and chromate (CrO₄²⁻) has a charge of -2.
- The charges are already balanced, so the formula is PbCrO₄.
(d) Calcium fluoride
- Calcium (Ca²⁺) has a charge of +2, and fluoride (F⁻) has a charge of -1.
- To balance the charges, we need two fluoride ions for each calcium ion. The formula is CaF₂.
(e) Iron(II) phosphate
- Iron(II) has a charge of +2, and phosphate (PO₄³⁻) has a charge of -3.
- To balance the charges, we need three iron ions for two phosphate ions. The formula is Fe₃(PO₄)₂.
(f) Lithium hydrogen sulfite
- Lithium (Li⁺) has a charge of +1, and hydrogen sulfite (HSO₃⁻) has a charge of -1.
- The charges are balanced, so the formula is LiHSO₃.
Explanation:
When writing the formula for an ionic compound, the charges of the ions need to balance out. The positive charge from the cation (the metal ion) must be equal to the negative charge from the anion (the non-metal or polyatomic ion). If the charges are not already balanced, you need to adjust the ratio of cations and anions by using subscripts to ensure the total positive charge is equal to the total negative charge.
For example:
- In copper(I) chlorate (CuClO₃), copper has a +1 charge and chlorate has a -1 charge, so the formula is CuClO₃.
- In calcium fluoride (CaF₂), calcium has a +2 charge, and fluoride has a -1 charge. To balance the charges, two fluoride ions are required for each calcium ion, hence the formula is CaF₂.
The process involves recognizing the charges of the ions involved and adjusting the stoichiometry (subscripts) to balance the overall charge of the compound.
