Question

How many grams of Ca(OH)2 are needed to produce 500ml of 1.66 M Ca(OH)2 solution

Answer 1

First, determine how many moles are present in solution. Once you have this, you can convert to grams to find the number of grams in your final solution.

To determine how many moles are in your solution, simply multiply Molarity by Volume. Molarity is expressed in units of moles/liter, so your liters will cancel out leaving you with moles. Just ensure that your units of volume are all expressed in liters before attempting the calculation:

1.66 mol/L x 0.5 L = 0.83 mol

To determine how many grams are present in a mole, you will need the molar mass of Ca(OH)2. Using a periodic table, we can determine the molar mass by adding together 1 Ca, 2 O, and 2 H. This turns out to be approximately (40+32+2) = 74 g/mol. Again, paying attention to units we can see that by multiplying moles by molar mass, we will cancel out moles and leave us with grams.

0.83 mol x 74 g/mol = 61.42 grams of Ca(OH)2

Answer: 61.42 grams of Ca(OH)2 are needed to produce 500 mL of a 1.66 M solution.