Question

You prepared a 0.250 M NH3 solution by diluting 8.45 (±0.04) mL of 28.0 (±0.5) wt%NH3 [density ± 0.899 (± 0.003) g/mL] up to 500.0 (± 0.2) mL. Find the uncertainty in 0.250 M. (Assume: The molecular mass of NH3, 17.0305 g/mol, has negligible uncertainty relative to other uncertainties in this problem).

Answer 1

To find the uncertainty in 0.250 M NH3, we need to consider the uncertainties in the given values. The uncertainty in the molarity can be calculated using the formula. Using the provided uncertainties, the uncertainty in the final volume is ± 0.2 mL and the uncertainty in the initial volume is ± 0.04 mL. Therefore, the uncertainty in the molarity of the 0.250 M NH3 solution is approximately ± 0.0051 M.

Step-by-step explanation:

To find the uncertainty in 0.250 M NH3, we need to consider the uncertainties in the given values. Let's calculate the uncertainty in the molarity using the formula:

Uncertainty in molarity = (Uncertainty in final volume / final volume) + (Uncertainty in initial volume / initial volume)

Using the provided uncertainties, the uncertainty in the final volume is ± 0.2 mL and the uncertainty in the initial volume is ± 0.04 mL. The final volume is 500.0 mL, and the initial volume is 8.45 mL. Plugging these values into the formula, we get:

Uncertainty in molarity = (0.2 mL / 500.0 mL) + (0.04 mL / 8.45 mL) = 0.0004 + 0.0047 ≈ 0.0051

Therefore, the uncertainty in the molarity of the 0.250 M NH3 solution is approximately ± 0.0051 M.