Practical 3 & 4: Gravimetric Analysis of Sulfate 65410 Skills for the Professional Chemist conecum re volupta evelignis Graphics created by Ullupta pe et doluptuam.
2 Gravimetric Analysis • Gravimetric analysis is the quantitative determination of an analyte by mass • We can use the precipitation method of gravimetric analysis to separate ions from a solution and find the amount of an aqueous ionic compound in a sample: 1. Precipitation reaction This is 2. Filter where you are up to 3. Wash the precipitate 4. Dry precipitate 5. Weigh the precipitate
3 Gravimetric Analysis • When analysing something by mass, what is important? – Clean and dry glassware – Use of an analytical balance – Minimising sources of systematic error
4 Aims of this Practical • Calculate the required volume of 0.5 M BaCl 2 that needs to be added to the solution in order to precipitate ALL of the sulfate ions • Perform the experiment by following the general procedure provided in the guidelines • Calculate the mass of sulfate and sulfur present in the lawn fertiliser and compare with manufacturer’s quoted amounts • Re-design the experiment so that others can replicate your methods • Consider the risk assessment process and safety procedures that need to be followed before you undertake an experiment
5 Important considerations • How long will this experiment take? Can it be done in a 1 hour class or does it require a double period or more? • Do you need individual bottles of reagents in small volumes? • Think about your safety considerations – Should you be wearing gloves and why? – Is it hazardous? – Do we need to limit volumes? – Is it hot?
6 Laboratory Report 3 • Your report will consist of: – A re-written experimental method – Post-laboratory worksheet – Risk assessment (details given in workshop) – Scanned copy of lab notes • Keep in mind the purpose and audience for this report – a High School chemistry practical class • Further information is in the Practical 3 guide on UTSOnline
7 Laboratory Report 3 submission • Your individual report will be submitted as ONE FILE and must contain your scanned laboratory notes. – Convert report to pdf – Scan lab notes (as pdf) – Merge pdf files (using a website such as pdfmerge.com or Adobe Acrobat Pro DC) – Submit via the link in UTSOnline Due: In 2 weeks (Week 8)
8 Reminder: Report 2 is DUE tonight • Practical report 2 is due at 11:59 pm tonight • Submit via the link on UTSOnline • Make sure you look at the marking guidelines before submitting
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