1.

A small sample of Uranium metal (0.119 gm) is heated to 900^(@) C in air to give 0.135 gm of a dark oxide, U_(x) O_(y). Then [U = 238]

Answer»

Moles of `U_(X) O_(y)` formed `= 5 xx 10^(-3)`
Empirical formula is `UO_(2)`
Moles of Uranium metal used `5 xx 10^(-4)`
Moles of oxygen gas used `1 xx 10^(-3)`

Solution :`{:(U,+,O_(2),rarr,U_(x)O_(y),):}`
Moles of `U = (0.119)/(238) = 0.5 xx 10^(-3) = 5 xx 10^(-4)`
Mass of oxygen in oxide `= (0.135 - 0.119)`
`= 0.016 gm`
Moles of oxgyen ATOM in oxide `= (0.016)/(16) = 1 xx 10^(-3)`
`{:(U,,O,),(5 xx 10^(-4),,1 xx 10^(-3),),(0.5,:,1,),(1,:,2,):}`
Emprical formula `= UO_(2)`


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