Unit 1: The Scientific Endeavour Flashcards
Qualitative Data
Involves the 5 senses
(sight, touch, smell, taste, hearing)
Usually descriptive or what you can observe with your 5 senses
(e.g. heavy, long, fast)
Quantitative Data
Involves senses and measurements taken using instruments
Has units, measurements or a numerical value
e.g. 2 ants, 500g, 50s
Observation
- the act of attentive monitoring or perceiving, mediated through our five senses
- the measurement, collection or recording of data, mediated through instruments, especially during an experiment
Inferences
• a logical conclusion that can possibly be derived based on the observations made.
Dependent
Variable
Variable Measured (VM)
A dependent variable is what you measure in an experiment and what is affected
during the experiment. The dependent variable is affected during the experiment.
The dependent variable responds to the independent variable.
Independent Variable
Variable Changed (VC)
An independent variable is the variable you have control over, what you can choose
and manipulate. It is usually what you think will affect the dependent variable.
Constants/ Fixed Variables
The factors within an experiment that are kept the same for all groups or trials in an attempt to reduce the influence of irrelevant variables.
Control Group
Controlled Variables (?)
The group in an experiment that receives the exact treatment as the experimental groups except it does not receive any change of the independent variable. It is the
group to which the experimental groups are compared.
Hypothesis
A tentative (i.e. not final and definite) and testable proposed explanation for an
observed phenomenon. It is based on observation and prior knowledge of the
system.
• It refers to only one dependent variable and one independent variable.
• It is written as a definite statement, and not a question.
• It is testable by experimentation.
Observations
The act of attentive monitoring or perceiving, mediated through our five senses and the measurement, collection or recording of data, mediated through instruments, especially during an experiment.
Inferences
A conclusion, based on facts, which a person perceives to be true.
Repeats
The replication of experimental and control groups is used to decrease the influence
of variations associated with the independent variable and researcher measurement error.
Accuracy
Readings are closest to real value but may not be close to one another.
Precision
Readings are closer to one another even if it is far from real value.
Parallax Error
Parallax Error
• Occurs when you did not read the marking of an instrument at eye level or did not read perpendicularly above the marking
• error in reading an instrument as a result of not viewing the measurement scale from the correct position.
• Unpredictable (human error)
• Can be corrected by reading the marking of an instrument at eye level or reading perpendicularly above the marking
• Factors that contribute to unpredictable errors include unpredictable environmental conditions and human reaction time in operating a stopwatch.
Zero Error
- Occurs when a measuring instrument gives a reading not zero (when nothing is placed on it) when the true reading at that time is zero.
- Consistent error = consistently inaccurate
- Can be corrected by pressing the ‘tare’ button before placing something on the electronic balance or subtract (the amt that error causing) from final reading of mass
- Occurs in measuring instruments e.g. weighing scale
Luminous Flame
- flame is not as hot as non-luminous flame
- yellowish-orange, blue
- sooty
- flickering and unsteady
- more visible
- obtain when air-hole is closed
- flame burns less efficiently (incomplete combustion)
Non-Luminous Flame
- flame is very hot
- pale blue, blue
- not sooty
- steady
- less visible
- obtained when air-hole is open
- flame burns more efficiently (complete combustion)
Why is a luminous flame yellow/orange?
It is due to the presence of carbon.
Why is heating with a Bunsen burner usually carried out with an open instead of a closed air-hole?
Opening the air-hole will produce a non-luminous flame which is hotter and burns more efficiently than a luminous flame.
What is obtained when the air-hole is closed?
Luminous Flame
What is the colour of a luminous flame?
yellowish-orange, blue
Which flame is sooty? (smoke like thing??)
How is soot produced?
Luminous Flame
Soot is produced when there is incomplete combustion / insufficient oxygen
Which flame is flickering and unsteady?
Luminous Flame
Which flame burns less efficiently? Why?
Luminous Flame
There is incomplete combustion/ insufficient oxygen
Which flame is very hot?
Non-Luminous Flame
Which flame is pale blue/ blue in colour?
Non-Luminous Flame
Which flame is not sooty?
Non-Luminous Flame
Which flame is steady?
Non-Luminous Flame
Which flame is less visible?
Non-Luminous Flame
Which flame burns more efficiently?
Why?
Non-Luminous Flame.
There is complete combustion/ sufficient oxygen.
What is the inner blue zone of the non-luminous flame made up of?
Air and unburnt gas
How does a strike-back flame occur?
A “strike back” flame may occur when the air-holes are fully open before you light up the Bunsen burner. There is too much air at the jet which results in the gas burning at the jet inside the barrel.
If your Bunsen burner has an accidental “strike back”, turn off the gas tap immediately and let the bunsen burner cool down before lighting it again.
Which flame do you leave the bunsen burner in when it is temporarily not in use?
Luminous flame.
This is to make the flame visible so as to avoid accidentally burning one’s self.
What is the function of the barrel in a Bunsen burner?
to raise the flame to a suitable height for burning
What is the function of the collar in a Bunsen Burner?
to control the amount of air entering the burner by opening or closing the air-holes
to open or close the air hole
What is the function of the gas tap of a bunsen burner?
to control the flow of gas to the bunsen burner
what is the function of the air hole in a bunsen burner?
to allow air to enter the burner
to allow air (oxygen) to mix with gas fuel
What is the function of the gas jet in a bunsen burner?
to enable the gas to rush out from the gas supply and to draw in air
What is the function of the base in a bunsen burner?
to support the burner so that it will not topple
How do you light a bunsen burner?
- close the air-hole
- hold a lighted match near the mouth of the barrel
- turn on the gas tap slowly (luminous flame)
- open the air-hole for heating (change to non luminous flame)
Attitudes for science?
Curiosity Perseverance Positive approach to failure Open-mindedness Co-operation with others Tolerance Impartiality Healthy scepticism Integrity Refusal to believe in superstitions
What is the scientific method (steps)?
- Observe
- Record observations or measurements
- Suggest a hypothesis
- Test the hypothesis
- Infer from data
- Evaluate
What are the safety rules when heating or mixing chemicals?
Wear goggles when heating or mixing chemicals.
Place flammable substances away from the naked flame.
Point the mouth of a test tube which is being heated away from yourself or your friends.
What do you do when accidents occur?
Report all accidents, injuries, breakage and spillage to your teacher immediately.
If any chemical gets into your eyes or mouth, rinse your eyes or mouth with plenty of water and report the incident to your teacher.
What are the steps involved in the scientific method to plan an experiment?
Make observations ↓ record observations or measurements ↓ suggest a hypothesis ↓ test the hypothesis ↓ infer from data ↓ ↓ valid hypothesis invalid hypothesis ↓ ↓ theory go back to recording observations or measurements
