A 2.18 g sample contains a mixture of XO and X_(2)O_(3). It reacts with 0.015 moles of K_(2)Cr_(2)O_(7) to oxidize the sample completely toform XO_(4)^(-) " and " Cr^(3+) . If 0.0187 mole of XO_(4)^(-)is formed , what is the atomic mass of X ?

A 2.18 g sample contains a mixture of XO and X_(2)O_(3). It reacts wit

1.	A 2.18 g sample contains a mixture of XO and X_(2)O_(3). It reacts with 0.015 moles of K_(2)Cr_(2)O_(7) to oxidize the sample completely toform XO_(4)^(-) " and " Cr^(3+) . If 0.0187 mole of XO_(4)^(-)is formed , what is the atomic mass of X ?
Answer» SOLUTION :`XO + K_(2)Cr_(2)O_(7) to Cr^(3+) + XO_(4)^(-)` `X_(2)O_(3) + K_(2)Cr_(2)O_(7) to Cr^(3+) + XO_(4)^(-)` Let, WT : of `K_(2)Cr_(2)O_(7) ` consumed by themixture `= 0.015 xx 6` Equivalents of `XO = x/(x + 16) xx 5` Equivalents of `X_(2)O_(3) = (2.18 -x)/(2x + 48) xx 8` ` :. x/(x + 16) xx 5 + (2.18 -x)/(2x - 14 8) xx 8 = 0.015 xx 6` Since 1 mole of XO gives 1 mole `XO_(4)^(-)` and 1 mole of `X_(2)O_(3)` gives 2 moles of `XO_(4)^(-)`, ` :. x/(x + 16) + (2x(2.18 -x))/(2x + 48) = 0.0187` On solving , `x = 99`