PRELAB
1. The densities of three solutions  with known concentrations ( 20% , 50%, and 70%), and one unknown solution were  determined. If  the densities of 20%, 50% and 70%  solutions are 0.69 and 0.58 and 0.49 g/mL, respectively, and the denisty of the unknown solution is 0.50 g/mL, what is the approximate concentration of the unknown solution? Hint: try to think of a range of two values between which the concentration of the unknown falls.
 
 
 
 
 
 
 
 
 
 
 
 

2. On a recent trip out of the country a  chemistry professor  found a golden-colored metal coin at a flee market. The person selling the coin priced it at $200, claiming it was pure gold. Being a well-equipped traveler and a chemist, the professor produced his graduated cylinder and electronic balance. The coin had a mass of 18.82 g and raised the  water level in the cylinder   from 5.2 mL to 7.3 mL. Show, by calculation, why he declined to purchase the coin. What, do you think, the major constituent of the coin was ? Justify your answer.