In Chemistry, an equation is either 100% correct or 0%. Examiners do not give partial credit for balanced equations with invalid radical valencies.
The 5 Silent Errors
- Writing $H$ instead of diatomic $H_2$ in displacement reactions.
- Omitting $\uparrow$ for gaseous products and $\downarrow$ for precipitates.
- Missing temperature conditions in the manufacture of cement or lime ($CaCO_3 \xrightarrow{\Delta} CaO + CO_2$).
- Incorrect radical formulas like $SO_3$ instead of $SO_4^{2-}$.
- Failing to mention the catalyst ($MnO_2$, $Fe/Mo$) where explicitly specified.
