Answer:
43.96secs
Explanation:
M1 = molar mass of NH3 = 14 + (3x1) = 14 + 3 = 17g/mol
t1 = time for NH3 to diffuse = 30secs
M2 = molar mass of HCl = 1 + 35.5 = 36.5g/mol
t2 = time for HCl to diffuse =?
From Graham's law of diffusion:
t2/t1 = √(M2/M1)
t2/30 = √(36.5/17)
t2/30 = 1.465
Cross multiply
t2 = 30 x 1.465
t2 = 43.96secs
Therefore it will take 43.96secs for the damp blue litmus paper to change colour for HCl.
