How many grams of calcium hydroxide Ca(OH)2 are needed to make 532.0 mL of a 1.90M solution?

m = 74.7 g Ca(OH)2

Explanation: To solve this problem we will use the formula for Molarity which is M = n /L, where n is the number of moles and L represents volume in liters. Derive for n to find moles then convert it to mass using the molar mass of the compound.

First convert mL to L

532.0 mL ( 1 L / 1000 mL ) = 0.532 L

n = M L

  = 1.90 M ( 0.532 L )

  = 1.01 moles Ca(OH)2

Convert moles to mass:

= 1.01 moles Ca(OH)2 x 74 g Ca(OH)2 / 1 mole Ca(OH)2

= 74.7 g Ca(OH)2

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)