Question

question 3. drag and formula and name for each binary ionic compound formed from
a) cobalt(iii) ion and chloride ion
formula:
name of the binary ionic compound:
b) ca²⁺ and br⁻
formula:
name of the binary ionic compound:

Explanation:

Part a) Step1: Determine Ions and Charges

Cobalt(III) ion is $\text{Co}^{3+}$, chloride ion is $\text{Cl}^-$. To balance charges, we need 3 $\text{Cl}^-$ for 1 $\text{Co}^{3+}$ (since $3(+1) + 1(+3) = 0$? Wait, no: charge balance is total positive = total negative. So $\text{Co}^{3+}$ (charge +3) and $\text{Cl}^-$ (charge -1). So number of $\text{Cl}^-$ needed is 3 to balance +3. So formula is $\text{CoCl}_3$.

Part a) Step2: Name the Compound

For binary ionic compounds with a metal that can have multiple charges (cobalt here, III), we use the Stock system. So name is Cobalt(III) chloride.

Part b) Step1: Determine Ions and Charges

$\text{Ca}^{2+}$ (charge +2) and $\text{Br}^-$ (charge -1). To balance charges, we need 2 $\text{Br}^-$ for 1 $\text{Ca}^{2+}$ (since $2(-1) + 1(+2) = 0$). So formula is $\text{CaBr}_2$.

Part b) Step2: Name the Compound

Calcium is a metal with only one common charge (+2), so we use the common name. Bromide is the anion. So name is Calcium bromide.

Answer:

a) Formula: $\text{CoCl}_3$; Name: Cobalt(III) chloride
b) Formula: $\text{CaBr}_2$; Name: Calcium bromide