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Find the molarity strength of a sample which is prepared by mixing \mathrm{7000 \mathrm{~mL}} of  \mathrm{0.5 \mathrm{M} \, \, \mathrm{H}_2 \mathrm{SO}_4} (specific gravity \mathrm{=1.03} ) and \mathrm{4 \mathrm{~L}} of  \mathrm{98 \%(\mathrm{w} / \mathrm{V})} of \mathrm{\mathrm{H}_2 \mathrm{SO}_4} (specific gravity \mathrm{=1.84} ). Also, the specific gravity of the resultant mixture is 1.4 and assume there is no loss of mass during mixing

Option: 1

0.41 m


Option: 2

0.85 m


Option: 3

4.2 m


Option: 4

0.5 m


Answers (1)

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 since there is no loss of mass due to mixing
\therefore  mass of \mathrm{7 L} of \mathrm{0.5 \mathrm{M\, \, H}_2 \mathrm{SO}_4+} mass of \mathrm{4 \mathrm{~L}} of  \mathrm{98 \%, \mathrm{H}_2 \mathrm{SO}_4 =} mass of resulting solution

\mathrm{\therefore \text { mass of solution }=7000 \times 1.03+4000 \times 1.84}

                                             =14570

\mathrm{\text { Hence, volume of solution }=\frac{14570}{1.4}}

                                                           \mathrm{=10407.14 \mathrm{~mL}}

Moles of \mathrm{\mathrm{H}_2 \mathrm{SO}_4} present in 1st kind of

\mathrm{ \begin{aligned} \text { acid solution } & =7000 \times 0.5 \times 10^{-3} \\ & =3.5 \text { moles } \end{aligned} }
Amount of. \mathrm{\mathrm{H}_2 \mathrm{SO}_4} present in \mathrm{4 \mathrm{~L}} of

second kind of solution \mathrm{=\frac{980 \times 4}{98} }

                                      \mathrm{=40 \text { moles }}

\therefore Total moles present in resulting

\mathrm{ \begin{aligned} \text { mixture } & =3.5+40 \\ & =43.5 \text { moles } \end{aligned} }

\therefore  concentration of resulting solution

             \mathrm{=\frac{43.5 \times 100}{10407.14}}
              \mathrm{=0.41 \mathrm{M}}

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Pankaj

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