Redox reactions

Question

(Cr2O7)2- + 2Al + 14H+ <—> 2Cr3+ + 2Al3++ 7H2O

1) how many ml of solution 1.50 M e (Cr2O7)2- are needed to act without residue with 0.8 grams of Al?

2) what is the concentration of the solution (Cr2O7)2-

Answer 1

I don't know what 1.5 M e (Cr2O7)2- means.