Blackboard chalk is a mixture of limestone and gypsum.A piece of blackboard chalk weighing 5.42g was immersed in HCl,the CO2 produced weighed 1.11g.What is the percentage of limestone in the chalk?Thank you

1 Answer
Oct 18, 2017

46,5%

Explanation:

You must write the balanced reaction: #CaCO_3 + 2HCl = CaCl_2 + H_2O+CO_2#
That means that from 1 mol of #CaCO_3 # whose MM is 100 g/mol you obtain 1 mol of #CO_2# whose MM is 44 g/mol . making the proportion You have #gCaCO_3= 1,11 xx 100/44= 2.52 g #
To found the % we have
#%CaCO_3= (gCaCO_3) /(g sample.) xx 100 = 2.52/5.42 xx 100 = 46.5% #