设所用稀盐酸中溶质的质量为x.
CaCO3+2HCl=CaCl2+H2O+CO2↑
100 73
10g x
100/10=73/x
x=7.3g
稀盐酸中溶质的质量分数是7.3/50*100%=14.6%
答：所用稀盐酸中溶质的质量分数是14.6%