General + Practical knowledge Flashcards
How accurate should calculations be?
As accurate as your least accurate measurement
How many grams are in a tonne?
1,000,000
What does volatile mean?
Easily evaporated at normal temperatures
How do you convert degrees Celsius into kelvin?
Add 273
What is a colorimeter?
It measures colour
What is mmol?
It is a milimole
It is 1/1000 of a mole
What is the formula for percentage uncertainty?
Uncertainty in the value
———————— X 100
Value
How do you work out percentage uncertainty?
Add all of the individual uncertainties together
Define accuracy
A value that is considered to be close to the true value
Define random error
Something that can not be predicted
Define systematic error
An error in a piece of equipment
Define interval
The quantity between readings
Define repeatable
The original scientist using the same method and equipment, then getting the same result
Define reproducible
Different people using different equipment to get the same results
Define validity
The suitability of the plan that you have put together to answer the question
What is a catagoric variable?
A named variable
What is a continuous variable?
A variable with a value
What is a control variable?
A variable that is kept constant
What are dependent variables?
They are the results gained from changing the independent variable
What are independent variables?
The variables that you change
What are the rules of electrolysis?
DC power supply connected to two rods (electrodes)
Dissolved in an electrolyte, something able to conduct electricity
Cathode: negative current, cations (positive ions) are attracted to it, reduction
Anode: positive current, anions (negative ions) are attracted to it, oxidation
How do you determine the products of electrolysis at each electrode?
The most reactive element will be produced
What is an alkyl group?
A hydrocarbon with one hydrocarbon missing
Ends in -thyl
How do you convert parts per million into a percentage?
1ppm = 0.0001%
Divide by 10,000
What is group 1 in an atom?
The energy level furthest from the nucleus
Define wet lab
Physical practical work
What is litmus paper?
Paper used to indicate acidity / alkalinity
Blue litmus paper: turns red under acidic conditions
Red litmus paper: turns blue under alkaline conditions
Why are anti bumping granules used?
They ensure smooth boiling by preventing the formation of large bubbles
What is the container for a sample in melting point apparatus?
Capillary tube
What is the catalyst for esterification?
Sulfuric acid
What is the purpose of sodium carbonate in esterification?
To remove remaining sulfuric and ethanoic acid
What is the purpose of a separating funnel?
To seperate immiscible liquids of different densities
The mixtures can be tapped off separately
What is the purpose of round bottomed flasks?
To ensure that heat is spread out evenly
What is the purpose of pear shaped flasks?
To allow the recovery of more material than round bottom flasks
Mostly used for distillation
How do you test for iodide ions in solution?
Add silver nitrate
A yellow precipitate is produced
What is the condition of the reagent in nucleophilic substitution reactions?
An excess of nucleophile
Why is an electric heater used over a bunsen burner?
Some products are flammable
How do you purify a solid?
Dissolve in a small amount of solvent Filter Cool to recrystallize Filter under reduced pressure (Buchner funnel) Wash and dry
