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Chemistry > Lecture 2 > Flashcards

Lecture 2 Flashcards

1
Q

What is matter?

A

anything that has mass and takes up space

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2
Q

Significant figure rules are to ?

A

prevent us from claiming a degree or precision that does not exist in measurement

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3
Q

T/F some of the evidence we collect will not be matter

A

True- they’re observations

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4
Q

Observations fall into what 2 categories?

A

Qualitative and quantitative data

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5
Q

What is qualitative data?

A

Observations an inv makes–involves analysis data such as words, pictures, or objects

is subjective in nature

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6
Q

When can you used qualitative data?

A
  • to form a consensus to decide wheat evidence to collect or direction to go in but never an absolute answer because of the issues with reproducibility
    ex. surveying or interviewing suspects
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7
Q

What is quantitative data?

A

the collection of number that involves analysis of numerical data

can be reproduced and is non-subjective in nature

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8
Q

What are intensive vs extensive properties when describing properties of matter?

A

Intensive: DO NOT depend on the amount of matter present (color, odor, density, pressure, boiling point)

Extensive: properties DO depend on the amount of matter present (mass, weight, volume, length)

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9
Q

How do you measure intensive properties?

A

They all fall under quantitative data

  • using a spectrometer and the wavelength to measure color
  • using spectrometry to measure odor compounds
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10
Q

T/F the mass and weight of an object are the same on earth

A

True

The weight changes but not the mass

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11
Q

Define mass

A

a measurement of the amount of matter in an object (grams)

  1. Use a balance to measure mass
  2. An object with mass has a quality called inertia.
  3. Mass is a measure of how much inertia an object displays.
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12
Q

Define weight

A

a measurement of the gravitational force of attraction of the earth acting on an object

weight is dependent on gravity

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13
Q

What is volume?

A

the 3 D space occupied by an object

V = a x b x h

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14
Q

What is length

A

measure of the amount of distance between the start and end of an object

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15
Q

What is the System De International (SI)?

A

A set of common units–they are base units used to communicate research findings

3 common ones: length, mass, and time

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16
Q

What are the base units for Electric Current and temperature?

A

Ampere and the Kelvin

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17
Q

What is Ampere?

A

the constant current which travels at a rate of 1 coulomb per second

AKA a package of electrical current

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18
Q

The Kelvin (K) is used for?

A

to measure temperature

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19
Q

Why is Kelvin known as the absolute temperature scale?

A

It does not use degrees, has an absolute zero of O k

20
Q

How you convert from degrees Celsius to Kelvin?

A

you add 273.15 to the Celsius temp

21
Q

T/F Fahrenheit degree scale IS NOT EQUIVALENT to the kelvin scale

A

True

22
Q

The unit for the amount of a substance is the _____ and the unit for luminous intensity called the

A

mole and candela

23
Q

What is a candela?

A

is a measured unit of how bright/strong the light being produced by a source may be.

there may be times in an investigation where knowing the amount of light present and being able to quantify that amount of light would be valuable to a case

24
Q

What are derived units?

A

Defined in terms of the seven base quantities via a system of quantity equations.

Created through the combination of the seven base units.

25
Q

What are three temperature scales that are in common use in science and industry.

A

Celsius, Fahrenheit, Kelvin

26
Q

What the difference between Celsius, Fahrenheit, Kelvin?

A

Celsius: the range of temperature between the freezing (0°) and boiling (100°)

Kelvin: an extension of the degree Celsius scale down to absolute zero

Fahrenheit: devised and evolved over time so that the freezing (32°) and boiling (212°) temperatures of water are whole numbers, but NOT round numbers as in the Celsius temperature scale.

27
Q

What is the conversion for Kelvin and Celsius?

A 
K = C + 273.15
C = K − 273.15
28
Q

What is the conversion for Fahrenheit and Celsius?

A

∘F =(∘C ×1.8) + 32.

∘C =(∘F − 32.) /1.8

29
Q

Normal body temperature is 98.6°F. What is this value on the Celsius scale?

A

∘C =(98.6 ∘F − 32.) /1.8
∘C = 66.6 / 1.8
∘C = 37

30
Q

The boiling point of water is 100° Celsius. What is this value on the kelvin and Fahrenheit scales?

A

K = 100 + 273.15
K = 373.15

now, 
∘F =(∘C ×1.8) + 32.
∘F =(100∘C ×1.8) + 32.
∘F = 180 + 32.
∘F = 212
31
Q

How are weight and mass different?

A
  1. Mass is a measurement of the amount of matter something contains, while Weight is the measurement of the pull of gravity on an object.
  2. Mass is measured by using a balance comparing a known amount of matter to an unknown amount of matter. Weight is measured on a scale.
  3. The Mass of an object doesn’t change when an object’s location changes. Weight, on the other hand does change with location.
32
Q

The standard unit of mass in the metric system is the _______

A

gram

33
Q

What is volume?

A

i. The volume of any solid, plasma, vacuum or theoretical object is how much three-dimensional space it occupies, often quantified numerically.
ii. Volume is commonly presented as gallons, milliliters, or cubic centimeters.

34
Q

What is scientific notation?

A

is a way to express very small or very large numbers

…is most often used in “scientific” calculations where the analysis must be very precise

…consists of two parts: A Number and a Power of 10. Ex: 1.22 x 103

For a number to be in correct scientific notation only one digit may be to the left of the decimal.

35
Q

In scientific notation moving left to right means what?

A

moving the decimal point to the left = a positive exponent.

Moving the decimal point to the right = a negative exponent.

36
Q

What are the rules for significant figures?

A
  1. Non-zero digits are always significant.
  2. Any zeros between two significant digits are significant.
  3. A final zero or trailing zeros in the decimal portion ONLY are significant.

2003 has 4 significant figures
00.00300 has 3 significant figures
00067000 has 2 significant figures
00067000.0 has 6 significant figures

37
Q

What is Dimensional analysis ?

A

is process by which scientists convert between one unit and another using conversion.

EX. converting temperatures from one scale to another or when we converted ft3 to cm3.

38
Q

There are three terms that are used by scientists in relation to their data’s reliability. What are they?

A

They are accuracy, precision and error.

39
Q

Define accuracy

A

how close a measured value is to the true, or accepted, value

AKA HOW CLOSE YOU ARE TO THE ACTUAL VALUE

40
Q

Define precision

A

how carefully a single measurement was made or how reproducible measurements in a series are.

i. HOW CONSISTENT A SERIES OF VALUES ARE WITH EACH OTHER

41
Q

What is error?

A

is anything that lessens a measurement’s accuracy or its precision.

42
Q

How to determine accuracy ?

A

to calculate the percent error using the known or true value:

(measured value - true value/ true value ) x 100%

Percent error is often shown as an absolute value

43
Q

T/F e. A large set of values for the same measurement generally improves the likelihood that the average value of this data set is correct or true.

A

True

44
Q

g. The precision of the data that you collect is best described by a statistic called the ______.

A

standard deviation

45
Q

What is SD?

A

The average amount by which the scores in the data set differ from the mean

46
Q

Small vs big SD mean what?

A

A small standard deviation means that the values are all closely grouped together and therefore more precise.

A large standard deviation means the values are not very similar and therefore less precise

Chemistry (12 decks)

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