Question

Which of the following are valid ways to make an ammonia/ammonium buffer for use in a laboratory? Explain your choices.  

Answer 1

The buffer is a ammonia /ammonium ion buffer So it requires NH3 and NH in solution. (a) Mix equal volumes of 1 M NH3 and 1 M NH: Mixing the two solutions will give a solution containing both NH3 and NH with 1 M concentration So it is a valid way to make this buffer. (b) Mix equal volumes of 1 M NH, and 0.01 M : This gives the required ions but the concentrations are not equal. So this is not a valid way. (c) Equal volumes of 1 M NH3 and1 M HCl will not give equal concentrations of NH3 and NH4. So it is not a valid way to make this buffer. (d) Some volume of 1 M NH3 and half as much HCI THis will give equal concentrations as half the HCI converts half the NH3 to ŅHÌ. NH, . H+ (from HCl)-) So this is also a valid way So only (a) and (d) are valid ways to make this buffer.