Question

determine the formula for each compound from its name.
lithium oxalate:
iron(iii) oxide:
tetraphosphorus decoxide:

Explanation:

1. Lithium Oxalate

Step1: Identify ions

Lithium ion: $Li^+$; Oxalate ion: $C_2O_4^{2-}$.

Step2: Balance charges

To balance $2-$ charge of oxalate, we need 2 $Li^+$ (since $2\times(+1) + (-2) = 0$).

Step3: Write formula

Combine ions: $Li_2C_2O_4$.

Step1: Identify ions

Iron(III) ion: $Fe^{3+}$; Oxide ion: $O^{2-}$.

Step2: Find least common multiple

LCM of 3 and 2 is 6. So, number of $Fe^{3+}$: $\frac{6}{3}=2$; number of $O^{2-}$: $\frac{6}{2}=3$.

Step3: Write formula

Combine ions: $Fe_2O_3$.

Step1: Interpret prefixes

"Tetra-" means 4 (for P); "Deca-" means 10 (for O, note: "decoxide" has a typo, should be "decoxide" → "decaoxide", so O atoms: 10).

Step2: Write formula

Use prefixes for subscripts: $P_4O_{10}$.

Answer:

$Li_2C_2O_4$

2. Iron(III) Oxide