Lecture Tools of analytical chemistry

Volumetric flask.Volumetric flasks are calibrated to contain an accurate volume.. Volumetric flasks are calibrated to contain an accurate volume.. Volumetric pipets accurately delive

Lecture 3

Tools of analytical chemistry

Volumetric flask.

Volumetric flasks are

calibrated to contain

an accurate volume

See the inside back

cover of the text for

tolerances of Class A

volumetric glassware.

Volumetric flasks are

calibrated to contain

an accurate volume

See the inside back

cover of the text for

tolerances of Class A

volumetric glassware.

©Gary Christian,

Analytical Chemistry,

6 th Ed (Wiley)

Measuring pipets

Transfer or volumetric pipets

Volumetric pipets accurately deliver a fixed volume

A small volume remains in the tip.

Volumetric pipets accurately deliver a fixed volume

A small volume remains in the tip.

Hamilton microliter syringe

Fig 2.12 Single-channel and multichannel digital

displacement pipets and microwell plates

These syringe pipets can reproducibly deliver a selected volume

They come in fixed and variable volumes The plastic tips are disposable.

These syringe pipets can reproducibly deliver a selected volume

They come in fixed and variable volumes The plastic tips are disposable.

©Gary Christian, Analytical Chemistry, 6 th Ed (Wiley)

Typical buret.

A 50-mL buret is marked in 0.1 mL increments

You interpolate to 0.01 mL, good to about ±0.02 mL Two readings are taken for every volume measurement.

A 50-mL buret is marked in 0.1 mL increments

You interpolate to 0.01 mL, good to about ±0.02 mL Two readings are taken for every volume measurement.

 How to read the markings of glassware?

 How to read the liquid level?

 How to clean glassware?

How to prepare solutions?

 Stock solutions:

 Weigh (or measure an appropriate volume for liquid)

 Dissolve

 Bring to desired volume

 Preparing solutions by dilution :

- Co is the stock solution’s concentration

- Vo is the volume of stock solution being diluted

- Cd is the dilute solution’s concentration

- Vd is the volume of the dilute solution.

 Whats’ the volume of 1000 ppm stock solution of Cu2+ needed to prepare 100 mL of 15 ppm solution of Cu2+?

  V0 = 1.5 mL

A) A laboratory procedure calls for 250 mL of an

approximately 0.10 M solution of H2C2O4 Describe how you would prepare this solution using solid H2C2O4•2H2O

B) A laboratory procedure calls for 250 mL of an approximately 0.10 M solution of HCl Describe how you would prepare this solution using a stock solution of concentrated HCl (C% =

37.5%; d = 1.19 g/ml).

1 a) What is the concentration (expressed as mol/L = M) of NaCl

when 32.0 g of NaCl is dissolved in water and diluted to 0.500 L?

2) b) How many grams of methanol (CH3OH, formula weight =

32.04) are contained in 0.100 L of 1.71 M aqueous methanol?

c) Any dilute aqueous solution has a density near 1.00 g/mL

Suppose the solution contains 1 ppm of solute; express the concentration of solute in g/L, mg/L, g/mL and mg/mL

3) Problem 4, Chapter 2, Harvey’s text book

4) Read Chapter 4 Characterisation of data * sources of errors, how to

eliminate errors.* The importance of stastical analysis, Gaussian distribution vs t-distribution