General Skills Flashcards
Most chemicals are irritants. What safety precautions should be undertaken for these?
Wear goggles
Clean up spills
Wash hands
What is usually dangerous about concentrated acids?
Corrosive
How to protect against concentrated acids
Wear goggles
Wear gloves
Safety precaution for any solvent labelled “toxic”
Use in a fume cupboard
How to work out what are appropriate significant figures
Use least accurate reading’s sig fig
What is formula for percentage uncertainty?
Error given
—————————- x100
Amount measured
In a 2dp balance what is the error given?
0.005
Hoe to reduce percentage uncertainty in mass measurements?
Use a more accurate balance eg a 4dp balance
Use a larger mass
For ‘mass by difference’ questions what do you do for percentage uncertainty?
Multiply error by 2
How many times do you read the volume on a burette?
What does this mean?
Twice
Use instrument error twice for percentage uncertainty
How many times are volume measured in a pipette?
Once
Therefore only use error given once
How many times do you measure volume in a volumetric flask ?
What does this mean?
Once
Use error given once
How many times do you use error for a measuring cylinder collecting volume of gas?
How do you reduce error of this?
Use error Twice
Use a gas syringe to collect gas as it is more accurate
Why are measuring cylinders inappropriate for titrations?
Their uncertainty is much greater than a burette or pipette
Why are beakers inappropriate to use in making up standard solutions?
Uncertainty is much greater than that of a volumetric flask
