Question

You need to make a very dilute solution of sodium phosphate dihydrate (MW 142 g/mol, FW 178 g/mol). How many grams of sodium phosphate dihydrate do you need to make 500 mL of a 2 M stock solution? How many mL of the stock solution do you need to make 100 mL of a 5 mM solution?

Answer 1

first question is 178 g of sodium phosphate dihydrate. second question is 0.25 mL

Step-by-step explanation:

To know the number of grams from the number of moles
`(0.5L*2mol/L)= 1mol`. 1 mol is equal to 178 g. Second question mL of the stock is obtained from
`(0.1L*5.0^-3mol/L)/2mol/L`.