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The domestic water supply is treated by bleaching powder to remove unhygienic species in water and to make it safe for drinking water. However, this given rise to `Ca^(2+)` and `Cl^(-)` ion contamination in water. Both these ions are also injurious for health if a minimum concentration is crossed. The chloride ions are tested by a kit provided by many companies having `AgNO_(3)` solution that is added drop by drop to `23 mL` of water sample to which an indicator has been added. When sufficient silver nitrate is added to remove `Cl^(-1)` ions as `AgCl` solid, the solid turns orange. The colour change is noticed by addition of `AgNO_(3)` having molar concentration such that each drop `(0.05 mL)` of `AgNO_(3)` converts `12.5 mg` of `Cl^(-)` ions `AgCl`. If `12` drops of `AgNO_(3)` solution are used to reach the colour point, what mass of chloride ion is present in one litre sample?A. `6.52 g`B. `7.150 g`C. `5.125 g`D. `1.25g` |
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Answer» Correct Answer - A `1` drop `AgNO_(3)= 12.5xx10^(-3)g Cl^(-)` `therefore 12 "drop" AgNO_(3)=12.5xx10^(-3)xx12 "mole" Cl^(-)` `=150xx10^(-3)g Cl^(-1)` Also, `23 mL` sample `=0.15 gCl^(-1)` `therefore 1000 mL` sample `=(0.15xx1000)/(23)gCl^(-)//"litre solution"` |
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