Study text: "Essential Mathematics and Statistics for Science", 2nd Edition,

G Currell & A A Dowman, Wiley-Blackwell, 2009

G Currell & A A Dowman, Wiley-Blackwell, 2009

- A mass of solute is to be weighed out in a balance with a quoted accuracy of ±0.5 mg and then dissolved in solvent in a 1.0 L (dm
^{3}) volumetric flask with a quoted tolerance of 0.8 mL (cm^{-3}). What is the minimum mass of solute that can be weighed such that the uncertainty in the mass is*less than*the uncertainty in the volume.- 2.5 g
- 0.625 g
- 0.40 g
- 0.25 g

- Which ONE of the following statements is NOT correct.
- For a 10 mL pipette that has a quoted tolerance of ±0.04 mL, the true volume of the pipette should be somewhere between 9.96 mL and 10.04 mL
- For a 10 mL pipette that has a quoted tolerance of ±0.04 mL, the expectation is that there is a 100% probability that the true volume of the pipette should be somewhere between 9.96 mL and 10.04 mL
- For an experimental result given as 24.6 ±0.2(sd), the expectation is that the true value lies between 24.4 and 24.8.
- For an experimental result given as 24.6 ±0.2(sd), the expectation is that there is a 68% probability that the true value lies between 24.4 and 24.8.

- When combining uncertainties in a dilution calculation, the quoted tolerance of ±0.1 mL for a 50 mL pipette can be considered to be equivalent to a
*standard deviation uncertainty*of:- 0.1 × 2 = 0.2 mL
- 0.1 / √3 ≈ 0.1 × 0.6 = 0.06 mL
- 0.1 × 0.5 = 0.05 mL
- 0.1 / √6 ≈ 0.1 × 0.4 = 0.04 mL

- A volume of 4 mL is transferred using two 2 mL volumes. If the
*standard uncertainty*for a 2 mL pipette is 0.012 mL, which of the following statements is*completely*correct.- The standard uncertainty for the 4 mL volume transferred using
*the same*2 mL pipette*twice*will be 0.017 mL - The standard uncertainty for the 4 mL volume transferred using
*two different*2 mL pipettes will be 0.017 mL - It does not make any difference whether one pipette is used twice, or two different pipettes are used, the standard uncertainty for the 4 mL volume transferred will be 0.024 mL
- It does not make any difference whether one pipette is used twice, or two different pipettes are used, the standard uncertainty for the 4 mL volume transferred will be 0.017 mL

- The standard uncertainty for the 4 mL volume transferred using
- 10 mL of a solution with concentration exactly equal to 40.00 ppm is transferred using a bulb pipette with a standard uncertainty of 0.024 mL and made up to a volume of 100 mL using solvent in a 100 mL volumetric flask with a standard uncertainty of 0.12 mL.

Calculate the concentration, and standard uncertainty (to 2sf), of the diluted solution.- 4.000 ±0.014(sd)
- 4.000 ±0.036(sd)
- 4.000 ±0.0027(sd)
- 4.000 ±0.011(sd)