Practical 3 & 4: Gravimetric Analysis of Sulfate 65410 Skills - - PowerPoint PPT Presentation

Practical 3 & 4: Gravimetric Analysis

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65410 Skills for the Professional Chemist

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
• 2. Filter
• 3. Wash the precipitate
• 4. Dry precipitate
• 5. Weigh the precipitate

This is where you are up to

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 BaCl2 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