Question

optimum volume HCl = 30.mL

0.1M = HCl molarity

Calculate grams THAM that will completely react with HCl.

The answer is 2.0 g THAM. Can someone show how to get this answer?

Answer 1

HCl's reaction with Tris is a neutralization reaction in which both the acid and base are monoprotic and monobasic implying that they react in 1:1 equivalents. Thus the moles of HCl will react completely with that many moles of Tris and vice versa.

Molarity is defined as the number of moles of a compound per litre or 1000mL of solvent which here is HCl and water respectively. Therefore, if the concentration of HCl used is 0.1M it means there is 0.1mol of HCl in 1000mL of solution which gives the amount of HCl in 1mL as 0.1/1000 = 0.0001mol. From this, the moles of HCl in 30mL of 0.1M HCl solution is calculated as 0.0001*30 = 0.003mol implying that it will require 0.003mol of Tris to completely consume that much HCl.

The molar mass of Tris is 121.14g/mol which shows that 121.14g of Tris makes up 1mol. So, 0.003mol of Tris will be 0.3634g.

NOTE: Tris is another common name for THAM which is tris(hydroxymethyl)aminomethane.