Chemistry
posted by K .
A 0.188g sample of unknown metal, X (s), produced 71.4 ml of hydrogen gas when reacted with HCL according to the equation: X(s)+2HCL(aq)>XCl2(aq)+H2(g)
The gas was collected over water at 23 degrees Celsius. The levels of water inside and outside the gas collecting tube are identical. The vepor pressure of water at 23 degrees Celsius is 21.1 mmHg and the atmospheric pressure is 752 mmHg. Calculate the molar mass of the unknown metal, X. (R=0.0821Latm/molK)

Use PV = nRT to solve for n
P = (75221.1)/760
V = 0.0714 L
T = 296 K
The equation in the problems tells you that mols H2 equal mols X.
atomic mass X = grams/moles.
My best guess is Zn but you need to do the work. I don't know how close the value is supposed to be but I don't get exactly the atomic mass Zn. Check my work carefully. 
Glycerol is a syrup liquid often used in cosmetics and soaps. A 2.50L sample of pure glycerol has a mass of 3.15 x 10 to the 3rd power grams. What is the density in grams per cubic cm