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Chem 205 > Domains, Phases, Matter, classification, Physical and chemical properties, Measurements, Mathematical treatment > Flashcards

Domains, Phases, Matter, classification, Physical and chemical properties, Measurements, Mathematical treatment Flashcards

Week 1

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1
Q

What is accuracy?

A

The agreement of a particular value with the true value
(or accepted value)

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2
Q

What is precision?

A

the degree of agreement among several measurements of the same quantity.

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3
Q

What are 3 rules for counting SF in a given number?

A

Non-zero integers always count as sig.figs. 345 m

Captive zeros always count as sig.figs. 16.07 mL

Leading zeros do NOT count as sig.figs; they indicate order of magnitude. ex: 0.0486 g has 3 SF

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4
Q

Why do we want to be precise in our rounding?

A

to make sure our numerical results honestly reflect the level of uncertainty in the raw data used.

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5
Q

Density

A

A quantifiable physical property of substances

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6
Q

Formula of density

A

mass/volume

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7
Q

What are the 5 steps in problem solving?

A
  1. Interpret the question.
    ▪ Determine what the problem is asking.
  2. Develop a plan of attack.
    ▪ Identify key principles.
    ▪ Sketch diagram / write chemical equation. ▪Organizeinformation: knownvs.unknown; +units. ▪ Break problem into simpler ones – take logical steps.
  3. Execute the plan.
    ▪ Show all units – do they yield desired units at end ? ▪ Don’t skip steps (& don’t round off prematurely).
  4. Check your answer.
    ▪ Common sense – is it a reasonable number ? ▪ Verify number of significant figures.
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8
Q

Sterling silver is a solid solution or “alloy” of silver (Ag) and copper (Cu). If a piece of a sterling silver necklace has a mass of 105.0 g and a volume of 10.12 mL, calculate the mass percent of silver in the necklace.
Assume that the volume of silver present plus the volume of copper present equals the total volume.

A
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9
Q

What are the 3 states of matter?

A

Solid
Liquid
Gases

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10
Q

What are the characteristics of Solids? (3)

A

▪ rigid shape, fixed volume.
▪ external shape can reflect particles’ arrangement.
▪ behaviour is reasonably well understood.

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11
Q

What re the characteristics of liquids? (2)

A

▪ fluid shape, but fixed volume.
▪ behaviour is not well understood
(i.e., complicated).

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12
Q

What are the characteristics of Gases?

A

▪expand to fill their container.
▪ behaviour very well understood
(& simple).

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13
Q

What is an Element?

A

Pure substance that cannot be subdivided into any other substances via physical or chemical methods (details about methods soon…)

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14
Q

What is the building block of any Element?

A

It is composed of only ONE kind of atom

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15
Q

What is a compound? (2)

A

▪ pure substance that requires chemical means to be further subdivided
▪ cannot separate into parent elements via physical separation methods

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16
Q

What is the building block of a component? (2)

A

composed of ≥ 2 elements’ atoms/ions in a fixed ratio

smallest group of atoms / ions that retains BOTH the composition & characteristics of the compound

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17
Q

Give an example of a chemical mean used to break down compounds into their constituent elements.

A

Electrolysis:
pass high current through liquid water to decompose it:

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18
Q

What is a covalent compound?

A

MOLECULE = atoms bonded together into a discrete unit

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19
Q

What is an Ionic compound?

A

IONS = charged (+,-) atoms or groups of atoms, which pack in ratios that give neutral combinations

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20
Q

The figures below represent four different samples of gas-phase matter.
The figures below represent four different samples of gas-phase matter.

A
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21
Q

Energy can be classified as _________or__________

A

Energy can be classified as Potential or Kinetic

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22
Q

What is Potential Energy (PE)?

A

energy associated with position

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23
Q

What 4 types of PE?

A
  • gravitationalE
  • chemical energy
  • electrostaticE
  • nuclear energy
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24
Q

Give an example of Gravitational PE.

A

an object held at a height, waterfalls.

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25
Q

Give an example of Chemical PE.

A

energy stored in molecules, due to bonds between atoms

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26
Q

Give an example of Electrostatic PE.

A

energy due to attractions between charged or partially charged particles

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27
Q

Give an example of Nuclear PE.

A

energy associated with attractions between nuclear particles (released via fission, fusion)

28
Q

What is Kinetic Energy (KE)?

A

energy associated with motion

29
Q

What are 4 types of KE?

A
  • Mechanical energy
  • Thermal Energy
  • Electrical Energy
  • Acoustic Energy
30
Q

What is Mechanical energy?

A

movement of a macrosopic object (e.g.,ball)

31
Q

What is Thermal energy?

A

Motion at the particulatel evel

32
Q

What is electrical energy?

A

movement of electrons in a conductor

33
Q

What is Acoustic energy?

A

compression-type wave motion

34
Q

What is the Kinetic Molecular Theory?

A

Matter consists of particles in constant motion

35
Q

Is KE proportional or inversely proportional to Temperature?

A

Proportional

Higher Temp = Faster Motion

36
Q

What causes particles to stick together?

A

Forces of attraction (Chem 206)

37
Q

Why is matter usually solid at low Temp.?

A

K.E. is low thus attractive forces seem large between particles

38
Q

Why is matter usually liquid or gas at high Temp.?

A

Higher K.E. thus the particles can overcome attractions

39
Q

How does density change with T?

A

as tempature decreases the density increases

40
Q

Why is that density increases at lower temperatures?

A

When particles’ kinetic energy decreases (i.e., at lower T), attractive forces between particles are more significant

e.g. particles move closer together and volume decreases

41
Q

When discussing density and temperature, what information must be specified?

A
  • Density
  • Volume
42
Q

Why is Water ice iunusual?

A

unlike water ice, most solids sink in their liquids

43
Q

What is a phase change?

A

Change of state

44
Q

What is a Physical change?

A

change in organization of particles, NOT composition

45
Q

What are characteristic propreties?

A

Temperatures at which changes

46
Q

What occurs in terms of energy when particles move closer together?

A

energy released as heat

47
Q

What occurs in terms of energy when particles move further apart together?

A

an energy input will be required

48
Q

How can we identify a substance (if it’s pure)?

A

▪ Colour, odour
▪ State of matter: Gas? Liquid? Solid?
▪Appearance: Shape? Powdered? Crystalline? Transparent? ▪ Melting point, boiling point, sublimation ability
▪ Solubility: How much will dissolve? In what will it dissolve?
▪ Electrical conductivity: conductor vs. insulator? ▪Malleability: easilydeformed?
▪Ductility: easilydrawnintoawire?
▪ Magnetic properties: attracted to magnetic field?
▪ Viscosity: for liquids: thick or thin? Does it flow easily?
▪ Density: mass per unit volume

49
Q

How could we classify matter in terms of mixtures vs. pure substances? (slide 41)

A
50
Q

What techniques could be used to separate heterogeneous mixtures? (3)

A

by filtration
by distillation
chromatography

51
Q

Describe the filtration method for seperating heterogeneous mixture. Slide 41

A
52
Q

Describe the distillation method for seperating heterogeneous mixture.

A
53
Q

Describe the chromatography method for seperating heterogeneous mixture.

A
  • To determine how many components are in mixture,
  • To test purity, or before attempting large scale separation
54
Q

The beaker contains a solution of a nonvolatile blue solid, copper sulfate (CuSO4), dissolved in water.
Which method below would separate the mixture into its two components, such that you would end up with a pure sample of each substance?

A. Distillation
B. Filtration
C. Chromatography
D. Sublimation

A

A. Distillation

55
Q

Physical change is the change in _______________________________________________ because ____________________________

A

Physical change is the change in
organization of atoms/molecules/ions because there is a change in interactions between molecules

56
Q

[48] Chemical change is the change in____________________________________________ because ___________________________________________

A

Chemical change is the change in composition of atoms/molecules/ions because there is a rearrangement of bonds between atoms/ions

57
Q
A
57
Q

In a physical change, the identity of substance(s) is:

A

unchanged

58
Q

In a chemical change, the identity of subtances is:

A

Changed

59
Q

Give 3 real life examples of physical changes.

A

melting butter
dissolving sugar in water
boiling water

60
Q

Give 3 real life examples of chemical changes.

A

burning butter digesting sugar reacting water with Na(s)

61
Q

Both physical and chemical changes involve:

A

transfers of energy: release (or absorption) of HEAT or LIGHT

62
Q

Give 4 examples of substances that react with oxygen and/or water.

A

▪ Combustion – of wood, gasoline “organic materials”
▪ Rusting – of iron
▪ Tarnishing – of silver (is not an example!!)
▪ Hardening – of cement

63
Q

Consider the following statements about sulfur (S), a yellow non-metallic element.
1) Sulfur is produced commercially by injecting steam into underground sulfur deposits to melt it.
2) It is then carried by the steam to the surface, where the sulfur separates from the water after cooling.
3) Sulfur burns in oxygen to form a choking gas, SO2, which reacts with water to form acid rain.
Which statements describe(s) a chemical reaction ?

A. Statement 2 only.
B. Statement 3 only.
C. Statements 1 & 2.
D. Statements 2 & 3.
E. All of them.

A

B

64
Q

[51] A student slowly heats some water (H2O) in a beaker. When the water reaches 30 C, bubbles begin to form on the walls of the beaker and eventually float to the surface. At 100 C, bubbles form rapidly throughout the water as it boils. Which option (A-E) describes the composition of the bubbles at the two temperatures?

A

C

Chem 205 (2 decks)

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