Question

fill in the name and empirical formula of each ionic compound that could be formed from the ions in this table:
some ionic compounds
cation anion empirical formula name of compound
$co^{3 + }$ $br^{-}$
$co^{2 + }$ $br^{-}$
$k^{+}$ $br^{-}$
$ca^{2 + }$ $br^{-}$

Explanation:

Step1: Determine formula for $Co^{3 +}$ and $Br^{-}$

The charges must balance. For $Co^{3+}$ and $Br^{-}$, we need 3 $Br^{-}$ ions to balance the + 3 charge of $Co^{3+}$. So the empirical formula is $CoBr_{3}$. The name is cobalt(III) bromide.

Step2: Determine formula for $Co^{2+}$ and $Br^{-}$

We need 2 $Br^{-}$ ions to balance the + 2 charge of $Co^{2+}$. So the empirical formula is $CoBr_{2}$. The name is cobalt(II) bromide.

Step3: Determine formula for $K^{+}$ and $Br^{-}$

The charges are + 1 and - 1, so the empirical formula is $KBr$. The name is potassium bromide.

Step4: Determine formula for $Ca^{2+}$ and $Br^{-}$

We need 2 $Br^{-}$ ions to balance the + 2 charge of $Ca^{2+}$. So the empirical formula is $CaBr_{2}$. The name is calcium bromide.

Answer:

cation	anion	empirical formula	name of compound
$Co^{2+}$	$Br^{-}$	$CoBr_{2}$	cobalt(II) bromide
$K^{+}$	$Br^{-}$	$KBr$	potassium bromide
$Ca^{2+}$	$Br^{-}$	$CaBr_{2}$	calcium bromide