#
50g of CaCO_{3}is added in 500mL 5N H_{2}SO_{4 }solution . calculate the normality of given mixture provided that **the react with each **other in the reaction CaCO3+H2SO4----> CaSO4+H2O when they react we use the formula Nmix= __ __**N1V1-N2V2/V1+V2** ** **why is that "minus -" sign n general why when they react we use this formula pls explain in detail

**N1V1-N2V2/V1+V2**

For CaCO

_{3}, N

_{2}= Gm equivalent of solute / Volume of solution (L)

${N}_{2}=\frac{Mass\left(gm\right)}{Equivalentmass\times Volumeofsolution\left(L\right)}\phantom{\rule{0ex}{0ex}}{N}_{2}{V}_{2}=\frac{50}{{\displaystyle \frac{100}{2}}}\phantom{\rule{0ex}{0ex}}{N}_{2}{V}_{2}=1$

For H

_{2}SO

_{4}: N

_{1}V

_{1}= 5 x 500 x 10

^{-3}= 2.5

From the formula:

${N}_{mix}=\frac{{N}_{1}{V}_{1}-{N}_{2}{V}_{2}}{{V}_{1}+{V}_{2}}\phantom{\rule{0ex}{0ex}}{N}_{mix}=\frac{2.5-1}{500}\times 1000\phantom{\rule{0ex}{0ex}}{N}_{mix}=3$

Here Acid and base reacting with each other and neutralising therefore we use N

_{1}V

_{1}- N

_{2}V

_{2}, if we use a mixture of acids or a mixture of bases then we add N

_{1}V

_{1}+ N

_{2}V

_{2}

Regards

**
**