Question

How many mmols of Tris would you need to prepare 100 mL of a 100mM Tris solution?

How many grams of Tris (MW 121.1) would you need ot prepare 100 mL of a 100 mM Tris solution?

Answer 1

Molarity = moles/ volume in Litres

mM = mmol / volume in L

mmol = mM x volume in L

1) How many mmols of Tris would you need to prepare 100 mL of a 100mM Tris solution?

= mM x volume in mL

= 100 mM x 0.1 L

= 10 mmol

Ans = 10 mmol

2) How many grams of Tris (MW 121.1) would you need ot prepare 100 mL of a 100 mM Tris solution?

Molarity = (Mass/ molar mass) x (1/ volume of solution in Litres)

Mass = Molarity x molar mass x  volume of solution in Litres

Given that Molarity of Tris = 100 mM = 0.1 M

volume of Tris solution = 100 mL = 0.1 L

molar mass of Tris = 121.1 g/mol

Hence,

mass of Tris = Molarity of Tris x molar mass ofTris x volume of Tris solution

= 0.1 M x 121.1 g/mol x 0.1 L

= 1.211 g

mass of Tris = 1.211 g

Therefore, 1.211 grams of Tris is needed to prepare 100 mL of 100 mM Tris solution