4 questions
A sample (\( 5.6 \, \text{g} \)) containing iron is completely dissolved in cold dilute \( \text{HCl} \) to prepare a \( 250 \, \text{mL} \) of solution. Titration of \( 25.0 \, \text{mL} \) of this solution requires \( 12.5 \, \text{mL} \) of \( 0.03 \, \text{M} \) \( \text{KMnO}_4 \) solution to reach the end point. Number of moles of \( \text{Fe}^{2+} \) present in \( 250 \, \text{mL} \) solution is \( x \times 10^{-2} \) (consider complete dissolution of \( \text{Fecl}_2 \)). The amount of iron present in the sample is \( y\% \) by weight.
(Assume: \( \text{KMnO}_4 \) reacts only with \( \text{Fe}^{2+} \) in the solution
Use: Molar mass of iron as \( 56 \, \text{g mol}^{-1} \))
The value of \( x \) is ____________.
\( \mathrm{H_2S} \) \( (\,5\, \text{moles}\,) \) reacts completely with acidified aqueous potassium permanganate solution. In this reaction, the number of moles of water produced is \( x \), and the number of moles of electrons involved is \( y \). The value of \( (x + y) \) is \( \_\_\_\_\_\_\_\_ \).
Consider the following molecules: \( \mathrm{Br_3O_8} \), \( \mathrm{F_2O} \), \( \mathrm{H_2S_4O_6} \), \( \mathrm{H_2S_5O_6} \) and \( \mathrm{C_3O_2} \). Count the number of atoms existing in their zero oxidation state in each molecule. Their sum is \( \_\_\_\_\_ \).
A sample (\( 5.6 \, \text{g} \)) containing iron is completely dissolved in cold dilute HCl to prepare a \( 250 \, \text{mL} \) of solution. Titration of \( 25.0 \, \text{mL} \) of this solution requires \( 12.5 \, \text{mL} \) of \( 0.03 \, \text{M} \) \( \mathrm{KMnO_4} \) solution to reach the end point. Number of moles of \( \mathrm{Fe^{2+}} \) present in \( 250 \, \text{mL} \) solution is \( x \times 10^{-2} \) (consider complete dissolution of \( \mathrm{Fecl_2} \) ). The amount of iron present in the sample is \( y\% \) by weight. (Assume: \( \mathrm{KMnO_4} \) reacts only with \( \mathrm{Fe^{2+}} \) in the solution
Use: Molar mass of iron as \( 56 \, \text{g mol}^{-1} \))
The value of \( y \) is ___________ .
