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Flashcards in Chemistry (terms + solutions unit) Deck (47):
1

What can be matter?

Anything that has mass and takes up space

2

Pure substances

Matter that only has one kind of particle. Ex: distilled water, oxygen gas, sugar and salt

New: characterized by definite properties such as melting point, boiling point, density and pressure.

-not a mixture of two
-can be an element or compound

3

Compounds

A pure substance that is composed of 2 or more different elements that are chemically combined. Ex: h20, co2

4

Elements

a pure substance that only has one kind of particle and cannot be broken down by chemical means (chemical methods). Made up of atoms Ex: hydrogen, nitrogen

5

Atoms

smallest unit of matter that takes part in chemical changes.

6

Mixtures

matter that has more than one kind of particle.

Can be homogenous or heterogenous

7

Solutions

a homogeneous mixture that has 2 or more substances.

Composed of solute and solvent

8

Homogeneous mixture

a mixture that is uniformly mixed and has only one phase. It is also a solution and is not easily separated. ex: vinegar, salt and water

-cannot see components

9

Heterogeneous mixture

a mixture that has more than one phase and is not uniformly mixed. It is easily separated (will separate over time) ex: sand water

-can see components
-does not dissolve

10

Mechanical mixtures

heterogeneous mixture that has different particles in which you can see. The particles are not uniformly mixed. Ex: soup

11

3 properties of acids

-Produce H+(as H3O+) ions in water (the hydronium ion is a hydrogen ion attached to a water molecule) Ions aqueous
-Taste sour/sharp
-Strong
-Corrode metals/many acids will burn skin
-Electrolytes
-React with bases to form a salt and water
-pH is less than 7
-Litmus paper red colour
(blue paper to red
red paper stay same)
-Compounds
-Solutions of acids conduct electricity

12

3 properties of bases

-Produce OH- (hydroxide) ions in water
-Ions aqueous
-Taste bitter, chalky
-Strong
-Feel soapy, slippery/many bases will burn skin
-Electrolytes
-React with acids to form salts and water
-pH greater than 7
-Litmus paper blue colour “Basic Blue”
(red paper to blue
blue paper stay same)
-Compounds
-Solutions of bases conduct electricity

13

Examples of Acids with formula

•Citric acid (weak acid) C6H8O7 →found in nature
•Formic acid (weak acid) HCO2H→bug stings
•Acetic acid (weak acid) CH3COOH→vinegar
•Carbonic acid H2CO3 →CO2 dissolved in air (acid dissolves limestone)

14

Examples of bases with formula

•Caffeine (weak base) C8H10N4O2
•NaOH sodium hydroxide →lye
•KOH potassium hydroxide→liquid soap
•Ba(OH)2 barium hydroxide→stabilizer for plastics
•Mg(OH)2 magnesium hydroxide→“MOM” Milk of magnesia
•Al(OH)3 aluminum hydroxide →Maalox (antacid)

15

pH scale

a numerical scale ranging from 0 to 14 that is used to classify aqueous solutions as acidic, basic, or neutral.
Is a way of expressing the strength of acids and bases. Instead of using very small numbers, we just use the NEGATIVE power of 10 on the Molarity of the H+ (or OH-) ion.
pH is a measure of hydrogen ions (H+). Hydrogen ions have lost their electron and become protons. pOH is a measure of hydroxide ions (OH-) in solution.

16

pH scale range

0-14
•7 is neutral (same number of hydrogen and hydroxide ions) →neither acidic or basic
•Lower than 7= acidic (more hydrogen ions than hydroxide ions)
•Greater than 7=basic (more hydroxide ions than hydrogen ions)

17

Ways to test pH

Ways to test pH
– Blue litmus paper (red = acid)
– Red litmus paper (blue = basic)
• Put a stirring rod into the solution and stir.
• Take the stirring rod out, and place a drop of the solution from the end of the stirring rod onto a piece of the paper
• Read and record the color change. Note what the color indicates.
• You should only use a small portion of the paper. You can use one piece of paper for several tests.
– pH paper (multi-colored)→not recommended as there can easily be errors
– pH meter (7 is neutral, less than 7 acid, greater than 7 base)→gives number
• Tests the voltage of the electrolyte
• Converts the voltage to pH
• Very cheap, accurate
• Must be calibrated with a buffer solution
Liquids:
pH indicator: a substance/chemical that changes colour to show the concentration of hydrogen ions and hydroxide ions in a solution
– Universal indicator (multi-colored)
• Mixtures of several indicators
• Strips soaked in universal indicator
– Indicators like phenolphthalein (bases)
• Turns colourless (neutral and acidic solutions)
• Turns pink (basic solutions)
– Natural indicators like red cabbage, radishes

• Indicators are dyes that can be added that will change color in the presence of an acid or base.
• Some indicators only work in a specific range of pH
• Once the drops are added, the sample is ruined
• Some dyes are natural, like radish skin or red cabbage
**neutral solutions don’t change colour

18

Burning
Glowing
Limewater
Cobalt

Burning splint tests for gases:
• Involves using a burning splint and placing it near an unknown gas
• If there is a “pop” sound →gas is hydrogen
• If the splint extinguishes →gas is carbon dioxide
Glowing splint test for gas:
• Involves using a glowing splint (still has heat but not burning) and placing it near an unknown gas
• If the glowing splint reignites and becomes burning →gas is oxygen

Limewater test
• Placing gas in limewater (usually blowing into limewater)
• If limewater becomes milky→gas is carbon dioxide
Cobalt chloride paper test:
• Used to test for unknown liquids
• Place cobalt chloride paper strip into unknown liquid
• If the paper turns from blue to pink→water

19

Noble gases

Noble Gases: Group VIIIA non-reactive (full outer shell), colourless and odorless, usually gases at room temperature, has 8 electrons on the outer shell, very stable and do not readily combine with others.

20

Halogens

Halogens: Group VIIA highly reactive (needs to gain one electron to have full shell), has 7 electrons on the outer shell, very corrosive, boiling point increases moving down the group

21

Alkali metals

Alkali metals: Group 1A highly reactive, low melting point, soft, kerosene gas must be kept at a certain temperature, has 1 electron on outer shell (loses one electron to have full shell). Reacts with water!

22

Alkaline Earth Metals

Alkaline Earth Metals: Group IIA reactive (not as much as alkali metals), ability to burn in air if heated, has 2 electrons on outer shell, produces bright light (fireworks)

23

Solute

The substance present in a lesser quantity in a solution (one being dissolved)

Ex: salt in salt water solution

24

Solvent

The substance present in a greater quantity in a solution (doing the dissolving) ex: water in salt water

25

Soluble

Refers to a substance that will dissolve in a given solvent ex: salt is soluble in water

"Like dissolve like" -->polarity

26

Insoluble

Refers to a substance that won't dissolve in a given solvent ex: sulfur is not soluble in water

If not dissolve, then is heterogenous mixture

27

Solubility

The maximum quantity of a solute that can dissolve in a given quantity of solvent at a given temperature, usually measured in g/L or g/100ml

-measure of how well a solute dissolves in a given solvent and temperature

Ex: the solubility in water is 18g/100mL at 25 degree Celsius

28

Concentrated Solution

A solution in which there is high solute to solvent ratio.

Ex: 5g of salt to 10 mL of water

*compare with dilute solution

29

Dilute Solution

A solution in which there is a low solute to solvent ratio.

Ex: 5 g of salt to 100 mL of water

*compare with concentrated solution

30

Unsaturated solution

A solution that is able to dissolve more solute because the solution has not yet reached its saturation point.

*compare with saturated solution

31

Saturated solution

A solution that has dissolved in it the maximum amount of solute it can hold at a given temperature. The solution is said to have reached its saturation point (at the temperature).

*compare with unsaturated solution

32

Supersaturated solution

A solution that contains more solute than it can normally hold at a given temperature.
How? The solution is prepared by heating a saturated solution and dissolving more solute in it than it can normally hold at a lower temperature and allowing the solution to cool.

-heat increases rate of dissolving

33

Miscible

refers to two liquids that are soluble in one another

Ex: water and food colouring

-liquid solute dissolves in liquid solvent

34

Immiscible

refers to two liquids that are not soluble in one another

Ex: water and oil

35

Aqueous

refers to a solution where a solute is dissolved in water

Ex: NaCl(s) -->Na(aq) + Cl(aq)

36

Tincture

Refers to any solution in which the solvent is ethanol (not water).

Ex: Tincture of iodine

37

Precipitate

An insoluble solid substance formed upon reaction of two aqueous solutions.

38

Hydrated Molecule

A molecule surrounded by water molecules

Ex: hydrate has H20 with a coefficient indicating the number of water molecules surrounding the base compound.

39

Types of Solutions

S dissolve in S: jewelry, statue, metal alloys
S dissolve in L: ice packs, hot packs, hot chocolate
S dissolve in G: solid aerosol (smoke)
L dissolve in S: mercury in dental alloy (fillings)
L dissolve in L: food colouring and water, antifreeze
L dissolve in G: clouds, perfume, water vapour in air
G dissolve in S: ice cream
G dissolve in L: carbonated beverages (CO2 in water)
G dissolve in G: air (includes O2, N2, CO2)

When determining type of solution, stick with original form

40

Factors affecting Solubility

3 -->how well a solute dissolves in a solvent

1. Nature of Solute or Solvent: different substances have different solubilities in a given solvent (some will dissolve better in one solvent over another). Ex: sulfur dissolves better with non polar substances like oil than polar substances like water.

2. Temperature: the solubility of most substances increases with an increase in temperature (because molecules move faster)-->Exception are gases (increase in temperature, decrease in solubility).

3. Pressure: Relates to gases -->increase in pressure increases solubility (does not affect solubilities of solids and liquids).
Ex: carbonated drinks (lid increases pressure)

41

Factors affecting the rate of dissolving

4 --> How fast

1. Size of Particles: smaller particles have larger surface area and increases rate of dissolving. Ex: sugar cube vs sugar granules

2. Stirring: stirring causes more solvent to interact with solutes (increases rate of dissolving). Ex: stirring vs no stirring.

3. Amount of Solute already dissolved: if the solution has approached the saturation point already, the dissolving takes place more slowly.


4. Temperature: as temperature increases, the rate of dissolving increases (except for gases). Also, increase temperature leads to increase saturation point (more can dissolve).

42

Concentration (Molarity)

Concentration is a measure of the amount of solute dissolved in a given quantity of solvent (Mol/L or M)

*Different from solubility-->maximum amount of solute that can be dissolved in a given quantity of solvent

Formula: C = n/V
n: the number of moles (might have to use n = m/mm first)
V= volume in Litres

43

How to Prepare a Solution with a specific concentration?

Given: volume (L), concentration, compound
1) choose a volumetric flask
2) Determine amount of solute needed
-calculate the number of moles (n = C*V)
-Then calculate molar mass of compound
-then determine the mass (m = n*mm)
3) weigh out the mass (g)
4) place the compound in a volumetric flask (choose volume: 1.00L)
5. Add a small volume of distilled water to dissolve the solute (swirl)
6. Fill the flask to the 1.00L (etc. depending on amount) line with distilled water -->use eyedropper at very end for accuracy

44

Diluting Solutions

Water is added to solutions to dilute (make less concentrated).

Formula: C1V1 = C2V2
Therefore n1=n2

C1= concentration of original or stock solution (mol/L)
V1= volume of original or stock solution (L)
C2= concentration of diluted solution (mol/L)
V2= total volume after dilution (L)

*every time concentrated solution becomes lower concentration -->dilution

45

Mixing solutions

When two of the same solutions are mixed together, there is a new concentration.

Formula: New concentration
C1V1 + C2V2/V1 + V2

*Never have to rearrange

C1= concentration of first solution (mol/L)
V1= volume of first solution (L)
C2= concentration of second solution
V2= volume of second solution

46

Atom vs. element

Atom: smallest particle of an element that has properties of that element
Ex: Carbon atom (bohr rutherford model)

Element: made up of atoms
Ex: Carbon is an element

Carrot is element; smallest carrot piece is atom

47

Compound Vs. Molecules

Compound: formed when atoms or molecules of different elements combine in a fixed proportion. Compounds are molecules with at least two different elements.

Molecule: formed when two or more atoms join together chemically and contains at least two different elements. -N2, O2 are molecules but not compounds because they only contain one kind of element

* All compounds are molecules, but not molecules are compounds.
Ex: Oxygen is not a compound