Answer:
Step-by-step explanation:
From the equation:
H2SO4(aq) + 2NaOH(aq) --> Na2SO4(aq) + 2H2O (l)
1 mole of the acid (H2SO4) and 2 moles of the base (NaOH) are required for complete neutralization.
mole of acid (H2SO4) present = molarity x volume
= 1 x 0.1 = 0.1 mole
Mole of base (NaOH) present = mass/molar mass
= 7/40 = 0.175 mole
The ratio of acid and base should be 1:2, hence the acid is slightly excessive in this case and the base is the limiting reagent that will determine the extent of the reaction.
Amount of excess acid = 0.1 - 0.175/2
= 0.0125 mole
volume of excess acid = mole/molarity
= 0.0125 x 1 = 0.0125 L
= 12.5 mL
Hence, the acid (H2SO4) was in excess by 12.5 mL.