Question

calculate molarity in .74g of Ca(OH)2 in 5ml of solution​

Answer 1

molarity is given as MOLES/LITER

normality is given as EQUIVALENTS/LITER

So, first figure out moles of Ca(OH)2; then liters of solution; then divide one by the other to get molarity.

moles Ca(OH)2 = 0.74 g x 1mol/74g = 0.01 moles

liters of solution = 15 ml x 1L/1000ml = 0.015L

Molarity = moles/liters = 0.01moles/0.015L = 0.007 molar

For normality, each mole of Ca(OH)2 yields TWO moles or TWO equivalents of OH-, so number of equivalents will be 2 x 0.01 = 0.02

normality = equivalents/liter = 0.02/0.015 = 1.33 normal

Thus, the normality is 2x (twice) the molarity because there are 2 equivalents for each mole.