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Chemistry 9-1 iGCSE Oxford AQA > Working Scientifically > Flashcards

Working Scientifically Flashcards

1
Q

What is a hazard?

A

Something that could potentially cause harm

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2
Q

Name 2 safety procedures one should take when working with sulfuric acid

A

Wear gloves and safety goggles

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3
Q

Name a safety procedure one should take when working with a Busen Burner

A

Put it on a heat proof mat (reduce risk of starting a fire)

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4
Q

What do you use a hypothesis for?

A

To make a prediction

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5
Q

What are investigations used for?

A

To see if there’s patterns or relationships between 2 variables

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6
Q

Evidence needs to be _________, ________ and ______

A

Repeatable, Reproducible and Valid

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7
Q

What is meant by repeatable?

A

If same person does an experiment using same method & equipment = get similar results

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8
Q

What is meant by reproducible?

A

If someone else does experiment, or different method or equipment used = similar results

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9
Q

What is meant by valid results?

A
  • Both repeatable and reproducible AND answer original question
  • Come from fair experiments
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10
Q

Data that’s repeatable and reproducible is _____

A

reliable

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11
Q

____ the Sample Size the Better

A

Bigger

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12
Q

Why should a sample size be big (name 2 reasons)

A
  • Sample should represent whole population
  • Smaller samples = harder to spot anomalies
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13
Q

Why do samples not include everyone? (name 2 reasons)

A

Would take too long and cost too much

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14
Q

How do you get a fair test?

A

By controlling variables

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15
Q

What is an independent variable?

A

Variable you change

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16
Q

What is a dependent variable?

A

Variable you measure when you change independent variable

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17
Q

What are control variables?

A

Variables you keep the same

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18
Q

Measuring equipment needs to be _____ enough

A

sensitive

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19
Q

What is meant by resolution?

A

Smallest change a measuring instrument can detect

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20
Q

How can you calibrate equipment?

A

By measuring known value

e.g. placing a thermometer in melting ice to see whether it reads zero

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21
Q

Data should be ____, _____, _____ and _____

A

Repeatable, Reproducible, Accurate and Precise

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22
Q

What is meant by accurate?

A

Results are really close to true answer/value

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23
Q

Why is counting bubbles not very accurate? (give 2 reasons)

A

∵ you might miss some bubbles or they might have different volumes

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24
Q

What is more accurate than counting bubbles?

A

Measure vol. of gas using gas syringe

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25
Q

How can you check the repeatability of your results?

A

By repeating readings to check results are similar

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26
Q

How can you check the reproducibility of your results?

A

Take 2nd set of readings with another instrument or different observer

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27
Q

What are precise results?

A

Data really close to mean of your repeated results i.e. not spread out

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28
Q

How can you increase the precision of your results?

A

Alter experiment - use a smaller scale

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29
Q

Why might results vary?

A

Due to random errors

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30
Q

What are random errors?

A

Unpredictable differences

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31
Q

Give an example of random error

A

e.g. human errors in measuring

32
Q

How can you reduce the effect of random errors on your results?

A

By repeat readings & finding the mean = make your results more precise + accurate (if there’s no systematic error)

33
Q

What is a systematic error?

A

Measurement wrong by same amount every time

34
Q

How can you fix a systematic error?

A

Use a different technique or a different set of equipment

35
Q

What is a measurement error?

A

Difference between measured value and true value

36
Q

What is a zero error?

A

Systematic error caused by using equipment that isn’t zeroed properly

37
Q

What are anomalies?

A

Results that don’t fit trend/pattern, away from line of best fit

38
Q

What do headings in tables need to include?

A

Units

39
Q

When calculating mean, what do you do if you have an anomalous result?

A

Ignore it

40
Q

When doing calculations, what should you round your answer to?

A

Round the answer to lowest number of significant figures given

41
Q

When do you draw a bar chart?

A

Independent variable = categoric or discrete (e.g. data counted in chucks, no in-between value = shoe sizes)

42
Q

When do you draw a line graph?

A

Both variables = continuous data

43
Q

How do you calculate rates from a graph?

A
44
Q

How do you find the rate at any point on a curved graph?

A

By drawing a tangent i.e. straight line that touches a single point a curve

45
Q

What’s the mutilple of unit for tera (T)?

A

1012

46
Q

What’s the mutilple of unit for giga (G)?

A

109

47
Q

What’s the mutilple of unit for mega (M)?

A

million = 106

48
Q

What’s the mutilple of unit for kilo (k)?

A

1000

49
Q

What’s the mutilple of unit for deci (d)?

A

0.1

50
Q

What’s the mutilple of unit for centi (c)?

A

0.01

51
Q

What’s the mutilple of unit for milli (m)?

A

0.001

52
Q

What’s the mutilple of unit for micro (µ)?

A

10-6

53
Q

What’s the mutilple of unit for nano (n)?

A

10-9

54
Q

What’s a conversion factor?

A

no. of times the smaller unit goes into large unit

55
Q

How do you get from a bigger unit to smaller unit?

A

× by conversion factor

56
Q

How do you get from a smaller unit to bigger unit?

A

÷ by conversion factor

57
Q

What is uncertainty?

A

Interval within which the true value can be expected to lie

58
Q

What is uncertainty? (simplier definition)

A

Amount of error your measurements might have

59
Q

When you repeat a measurement you get a different figure due to random error, what does this mean?

A

Means each result has some uncertainty to it

60
Q

Why do measurements you make have uncertainty?

A

Due to limits in resolution

61
Q

Larger the range = …

A

less precise your results are & more uncertainty

62
Q

How can you reduce uncertainty?

A

By measuring a greater amount

63
Q

How do you calculate uncertainty?

A
64
Q

Correlation ____ ____ mean Cause

A

DOES NOT

65
Q

Name 3 possible reasons for a correlation

A
  • Chance
  • Linked by 3rd variable
  • Cause
66
Q

Suggest 3 general changes to a method to improve quality of results

A
  • Increasing the no. of measurements you took
  • Changing the way you controlled a variable
  • Taking more measurements at narrower intervals (= more accurate result)
67
Q

Define Evidence

A

Data that’s valid

68
Q

Define Hypothesis

A

Proposal intended to explain certain fact or observation

69
Q

Define Fair Test

A

In which only independent variable has allowed to affect the dependent variable

70
Q

Define Valid

A
  • Free of error
  • Suitability of experiment to give accurate results
71
Q

Define Interval

A

Quantity between readings

72
Q

Define True value

A

Ideal measurement

73
Q

Define Data

A

Information = qualitative or quantitative

74
Q

Define Quantitative

A

Numbers

75
Q

Define Qualitative

A

Verbally done (words)

76
Q

Define Calibration

A

Marking a scale on a measuring instrument

77
Q

Define Prediction

A

State/suggest what will happen

Chemistry 9-1 iGCSE Oxford AQA (11 decks)

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