10 g sample of a mixture of CaCl2 and NaCl is treated to precipitate all the calcium as CaCO3. this CaCO3 is heated to convert all the Ca to CaO and final mass of CaO is 1.68g the mass % of CaCl2 in original mixture is ?

Question

options:-
1. 33.3%
2. 16.2%
3. 30%
4. 11%
please answer with full explanation

note : the numbers placed along the chemical formulas are all in subscript

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Answer 1 · 2017-10-09T15:20:59

Option 1.

33.3%

#sf(m_(CaO)=1.68color(white)(x)g)#

#sf(M_r[CaO]=56)#

#:.##sf(n_(CaO)=1.68/56=0.03)#

Action of heat on #sf(CaCO_3)# gives:

#sf(CaCO_3rarrCaO+CO_2)#

#:.##sf(n_(CaCO_3)=0.03)#

This was formed from:

#sf(Ca_((aq))^(2+)+CO_(3(aq))^(2-)rarrCaCO_(3(s)))#

#:.##sf(n_(CaCl_2)=0.03)#

#sf(M_r[CaCl_2]=40+71=111)#

#:.##sf(m_(CaCl_2)=0.03xx111=3.33color(white)(x)g)#

#:.# percentage #sf(CaCl_2)# #sf(=3.33/(10)xx100=33.3)#