JEE Main 2019 · Chemistry · s-Block, p-Block Elements and Hydrogen · easy

50 mL of a 6.8% (w/v) solution of hydrogen peroxide is completely decomposed to H2O and O2. Taking R=0.0821 L atm K^-1 mol^-1 and H = 1, O = 16, the…

Single correct option

50\ \mathrm{mL}

of a

6.8\%

(w/v) solution of hydrogen peroxide is completely decomposed to

\mathrm{H_2O}

and

\mathrm{O_2}

. Taking

R=0.0821\ \mathrm{L\,atm\,K^{-1}\,mol^{-1}}

and H = 1, O = 16, the volume of

\mathrm{O_2}

collected at

1\ \mathrm{atm}

and

27\,^\circ\mathrm{C}

is nearest to

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Answer: (A) $1.23\ \mathrm{L}$

6.8\%

w/v means

6.8

g per

100

mL, so

50

mL holds

3.4

\mathrm{H_2O_2}

=3.4/34 = 0.100

mol.

2\mathrm{H_2O_2} \to 2\mathrm{H_2O} + \mathrm{O_2}

gives

0.050

mol

\mathrm{O_2}

V = nRT/P = 0.050\times0.0821\times300/1 = 1.23\ \mathrm{L}

. Using the STP molar volume (

1.12\ \mathrm{L}

) ignores the stated temperature.

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