Working Scientifically
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What is a hazard?
Something that could potentially cause harm
Name 2 safety procedures one should take when working with sulfuric acid
Wear gloves and safety goggles
Name a safety procedure one should take when working with a Busen Burner
Put it on a heat proof mat (reduce risk of starting a fire)
What do you use a hypothesis for?
To make a prediction
What are investigations used for?
To see if there’s patterns or relationships between 2 variables
Evidence needs to be _________, ________ and ______
Repeatable, Reproducible and Valid
What is meant by repeatable?
If same person does an experiment using same method & equipment = get similar results
What is meant by reproducible?
If someone else does experiment, or different method or equipment used = similar results
What is meant by valid results?
• Both repeatable and reproducible AND answer original question • Come from fair experiments
Data that’s repeatable and reproducible is _____
reliable
____ the Sample Size the Better
Bigger
Why should a sample size be big (name 2 reasons)
• Sample should represent whole population • Smaller samples = harder to spot anomalies
Why do samples not include everyone? (name 2 reasons)
Would take too long and cost too much
How do you get a fair test?
By controlling variables
What is an independent variable?
Variable you change
What is a dependent variable?
Variable you measure when you change independent variable
What are control variables?
Variables you keep the same
Measuring equipment needs to be _____ enough
sensitive
What is meant by resolution?
Smallest change a measuring instrument can detect
How can you calibrate equipment?
By measuring known value e.g. placing a thermometer in melting ice to see whether it reads zero
Data should be ____, _____, _____ and _____
Repeatable, Reproducible, Accurate and Precise
What is meant by accurate?
Results are really close to true answer/value
Why is counting bubbles not very accurate? (give 2 reasons)
∵ you might miss some bubbles or they might have different volumes
What is more accurate than counting bubbles?
Measure vol. of gas using gas syringe