Question

To make up a solution of PBS, you need 15 mM Na2HPO4 (141.96 g/mol), 0.25M NaCl (58.44 g/mol), and 2 mM KH2PO4 (136.09 g/mol). How many grams of each will you need to make up 600 mL of PBS?

Answer 1

1.277 g of Na₂HPO₄, 8.766 g NaCl and 0.163 g KH₂PO₄ are need to make up 600 mL of PBS

15 mmol of Na₂HPO₄ is needed to make 1000ml of PBS

No. of mmol of Na₂HPO₄ is needed to make 600 ml of PBS = (15/1000) x 600 mmol

   = 9 mmol

=1.277 grams

0.25 moles of NaCl is needed to make 1000 ml of PBS

No. of moles of NaCl is needed to make 600 ml of PBS = 0.15 mole

= 8.766 grams

2 mmol of KH₂PO₄ is needed to make 1000 ml of PBS

No. of mmol of KH₂PO₄ is needed to make 600 ml of PBS = 1.2 mmol

= 0.163 grams