Question

Whcih one of the following is used as an acidic flux in metallurgy?

• A. $CaO$
• B. $Si{O}_2$
• C. $N{a}_{2}C{O}_3$
• D. $S{O}_2$

Answer 1

The correct option is B $Si{O}_2$

Silica is used as acidic flux because it is almost non-reactive due to the very high bond enthalpy of $Si-O$ bond. It resists the attack by halogens, dihydrogen and most of the acids and metals even at the elevated temperature. However, $HF$ and $NaOH$ react with them to form $Si{F}_4$ and $N{a}_{2}C{O}_3$ respectively.