Question

1. chemical formula

section ii: chemical formulas & ratio between ions
for each of the following pairs of ions, construct the chemical formula and identif

1. ca²+ cl⁻

formula:
ratio

1. cu²+ no₃¹-

formula:

1. na¹+ s²-

1. al³+ c₂o₄²-

Explanation:

Step1: Balance charges for $\text{Ca}^{2+}$ and $\text{Cl}^-$

$\text{Ca}^{2+}$ (2+) needs 2 $\text{Cl}^-$ (1- each) → $\text{CaCl}_2$, ratio $1:2$.

Step2: Balance charges for $\text{Na}^{1+}$ and $\text{S}^{2-}$

2 $\text{Na}^{1+}$ (1+ each) balance 1 $\text{S}^{2-}$ → $\text{Na}_2\text{S}$, ratio $2:1$.

Step3: Balance charges for $\text{Cu}^{2+}$ and $\text{NO}_3^{1-}$

$\text{Cu}^{2+}$ (2+) needs 2 $\text{NO}_3^{1-}$ → $\text{Cu(NO}_3\text{)}_2$, ratio $1:2$.

Step4: Balance charges for $\text{Al}^{3+}$ and $\text{C}_2\text{O}_4^{2-}$

2 $\text{Al}^{3+}$ (3+ each) balance 3 $\text{C}_2\text{O}_4^{2-}$ → $\text{Al}_2(\text{C}_2\text{O}_4)_3$, ratio $2:3$.

Answer:

1. Formula: $\text{CaCl}_2$; Ratio: $1:2$
2. Formula: $\text{Na}_2\text{S}$; Ratio: $2:1$
3. Formula: $\text{Cu(NO}_3\text{)}_2$; Ratio: $1:2$
4. Formula: $\text{Al}_2(\text{C}_2\text{O}_4)_3$; Ratio: $2:3$