195. 1 gram of a sample of CaCO, wa...
Question

# 195. 1 gram of a sample of CaCO, was strongly heated and the CO, liberated was absorbed in 100 mL of 0.5 M NaOH solution. Assuming 90% purity for the sample. How many mL of 0.5 M HCl would be required to react with the resulting solution to reach the end point in presence of phenolphthalein? (a) 73 mL (b) 41 mL (C) 82 mL (d) 100 mL

11th - 12th Class
Chemistry
Solution
162
4.0 (1 ratings)
MoL. Mass ob ( Q mathrm{aco}_{3}=100 ) Wo do moles ( (n)=frac{w}{n}=frac{1}{100}=0.01 ) Pocdotsinue ( Rightarrow 0.01 times frac{90}{100}=0.009 ) mol ob ( mathrm{CaCO}_{3} ) is arailable [ mathrm{CaCO}_{3} rightarrow mathrm{CaO}+mathrm{CO}_{2} ] ( therefore ) O.DO A MOL Ob CaCO g jues ( 0.009 mathrm{mol} ) ob ( mathrm{Co}_{2} ) No. ob moles ob ( left.mathrm{NaOH} text { reqd } € n^{prime}rightrangle=(M times V) ) ( =0.5 times frac{100}{1000}=0.05 mathrm{mols} ) Qut of 0.05 mol ob ( N ) a ( 0 mathrm{H} ), 0.009 is absonbed by Cao remaing ( =0.041 ) moles. NabH + HCe ( rightarrow ) Kace + H2D ( therefore ) O.OUI MOL Ob NODIT Requined O.D41 MoL ob HCR, Molarity ( =-0.5 ) ( (text { Given }) ) Volucue ( =frac{n}{M}=frac{O cdot O u !}{O cdot 5}=0.082 ) lit [ therefore H_{H C e}=82 mathrm{ML} ]