6. How many moles of NaOH are contained in 65 mL of a 2.20 M solution of
NaOH in H2O?
7. A solution of barium hydroxide, Ba(OH)2
, contains 4.285 g of barium hydroxide
in 100.0 mL of solution. What is the molarity of the solution?�
6. To find the moles of NaOH, we need to use the formula:
moles = concentration (in M) x volume (in L)
First, we need to convert the volume from milliliters to liters:
65 mL = 65/1000 L = 0.065 L
Now we can plug in the values:
moles = 2.20 M x 0.065 L = 0.143 moles
Therefore, there are 0.143 moles of NaOH in 65 mL of a 2.20 M solution.
7. To find the molarity of the solution, we need to use the formula:
molarity = moles of solute / volume of solution (in L)
First, we need to convert the mass of Ba(OH)2 to moles. The molar mass of Ba(OH)2 is:
(1 x atomic mass of Ba) + (2 x atomic mass of O) + (2 x atomic mass of H) = 137.33 g/mol
So the number of moles of Ba(OH)2 is:
moles = 4.285 g / 137.33 g/mol = 0.0312 moles
Now we can plug in the values for molarity:
molarity = 0.0312 moles / 0.100 L = 0.312 M
Therefore, the molarity of the solution is 0.312 M.