WAEC - Chemistry (2020 - No. 37)
If 20 cm\(^3\) of sodium hydroxide was neutralized by 20 cm\(^3\) of 0.01 mol dm\(^3\) tetraoxosulphate(VI) acid, what is the concentration of the sodium hydroxide solution?
0.010
0.020
0.100
0.150
Explanation
2NaOH + H\(_2\)SO\(_4\) → Na\(_2\)SO\(_4\) + 2H\(_2\)O
FRom the reaction, N\(_a\) = 1 ; N\(_b\) = 2
\(\frac{CaVa}{CbVb}\) = \(\frac{Na}{Nb}\)
\(\frac{{0.01}\times{20}}{{C_b}\times{20}}\) = \(\frac{1}{2}\)
cross multiply → C\(_b\) = \(\frac{{0.01}\times{20}\times{2}}{{20}\times{1}}\)
C\(_b\) = 0.02 mol/dm\(^3\)
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