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Chem Pracs (Headings (Procedure, Results, Risk Assessment, Discussion,…
Chem Pracs
Headings
Procedure
Results
Risk Assessment
Discussion
Equipment
Conclusion
Aim
Need To
Describe the procedures step by step
Present your data in appropriate format
List all equipment you need
Discuss the reliability & validity of your results & identify sources of error
Validity
Answers the aim
Variables are controlled except for the independent
Accuracy
How close you get to the expected result
Source of error
Systematic error
Problems with measurement e.g. reading error
Instrument error
Equipment should be calibrated
Built in error can be listed on the equipment
Reliability
Repetition of the method
Get consistent data that produces observable trend
Identify the variables
Dependent Variable
What you measure
Controlled Variable
Independent Variable
Justify your conclusion in terms of aim & results
Graphing
Unit on axis
Scale
Label axis
Key if needed
Title
Water
1C
Effect of the antifreeze on the boiling point of water
Ethylene Glycol
20% of solution will lower freezing point by 8 and raise boiling point by 2
Safety
Poisonous
Carried out in a fume cabinet & safety glasses
1A
Calculations of the density of water as a liquid and a solid
Density = Mass/Volume
Boiling- 0.9583
Room temp- 0.9982
Ice- 0.9182 gcm-3
Open cage crystalline structure
Ice is less dense because of its open cage structure
Equipment
Pipette
Safety
Glass
Water spills
Metals
2A
Reactivity of metals
Hot water
Theory
Balance eqn + half eqn.
Remember states
Link to calculations
Molar mass
Graphimetric anyalises
Empirical formula
Products
Calculate vol. of gas generated
At 25 degree celius and 100kPa, calculate volume of hydrogen gas produced
Volume gas = moles x molar volume
Safety
Bunsen Burners
Burn your skin
Have a Bunsen burner license
Acid
Burn or irritate your skin
Wear gloves
Equations
Metal + H2O(g)
Metal Oxide + H2
Metal + Acid
Salt + H2
Metal + H2O
Metal Hydroxide + H2
Metal + Oxygen
Metal Oxide
Acid
.
Cold water
.
4B
Empirical Formula
Practise
Safety
Burning Mg emits a right light do not look straight at it
Safety Glasses
Mg + O = MgO
Sources of error