What amount in gram do you need to prepare 25 ml of a 10% w/v solution of Tris (MWT 121 g/mol)?

Question

What amount in gram do you need to prepare 25 ml of a 10% w/v solution of Tris (MWT 121 g/mol)?

Answer 1

10% (w/v) by definition means 10 grams/100 ml solution.

Since you want 25 ml (and not 100 ml), then ...

10g/100 ml = 0.1 g/ml x 25 ml = 2.5 g needed to make 25 ml of a 10% (w/v) solution.

NOTE:  molar mass of Tris (121 g/mol) is not needed for these calculations.