Weeks 4 & 5 - Aqueous Soltutions & The Periodic Table

Question 1

What is osmotic pressure?

Answer 1

A measure of the number of solvent molecules is the pressure that must be applied to force the solvent molecules back through the membrane.

Question 2

What is a semipermeable membrane?

Answer 2

Membranes that are selective in the nutrients and products that pass through. Some substances may be able to move freely though but others may not.

Question 3

What is meant by “hydration” of ions?

Answer 3

The addition of water - in a aqueous solution, a cage of water molecules around ions or polar molecules of the solute.

Question 4

Molarity is?

Answer 4

The concentration of a solution in units of mol L-1. Also known as molar concentration and it is defined as a “C”.

Question 5

What is oxidation and reduction?

Answer 5

Oxidation - loss of electrons.

Reduction - gaining of election. The reducing agent is the agent that reduces the other.

Question 6

Define the meaning of osmosis.

Answer 6

The passage of solvent molecules but not those of solutes, through a semipermeable membrane . From high concentration to low concentration.

Question 7

What is an acid?

Answer 7

An acid is a species that donates H+

Question 8

What is a base?

Answer 8

A species that accepts H+

Question 9

What are colligative properties?

Answer 9

Are properties that depend only on the number of solute particles in solution not on the nature of the solute particles.

Question 10

What is a titration?

Answer 10

A solution of accurately known concentrations is added gradually to another solution of unknown concentration until the chemical reactions between the 2 solutions is complete.

Question 11

What is an equivalence point?

Answer 11

The point at which the reaction if complete - number of mole are equal and it finishes.

Question 12

What is a titration indicator?

Answer 12

A substance that changes colour at (or near) the equivalence point which is also known as the end point.

Question 13

What is a precipitate?

Answer 13

An insoluble solid that separates from solution.

Question 14

What is an oxidation number?

Answer 14

The charge the atom would have in a molecule (or an ionic compound) if electrons were completely transferred.

Question 15

What is a saturated solution?

Answer 15

Solvent holds a much solute as is possible at that temperature. Dissolved solute is in dynamic equilibrium with solid solute particles.

Question 16

What is an unsaturated solution?

Answer 16

Less than the maximum amount of solute for that temperature is dissolved in the solvent.

Question 17

What is a supersaturated solution?

Answer 17

Solvent holds more solute than is normally possible at that temperature. These solutions are unstable, crystallisation can usually be stimulated by adding a “seed crystal” or scratching the side of the flask.

Question 18

What does the term alkali mean?

Answer 18

A basic, ionic salt of an alkali metal or alkaline earth metal chemical element. An alkali also can be defined as a base that dissolves in water.

Question 19

What does the term chemical equilibrium mean?

Answer 19

A chemical reaction, chemical equilibrium is the state in which both reactants and products are present in concentrations which have no further tendency to change with time.

Question 20

In chemistry, an electrolyte is deemed what?

Answer 20

A substance that conducts electric current as a result of a dissociation into positively and negatively charged particles called ions,

Question 21

What is the difference between the two?

Ionic equation and net ionic equation.

Answer 21

Ionic equation : the equation is written where all cations and anions are separate and we keep the solubility rules intact.

Net ionic equation: shown with all the cations and anions dissociated with each other, then the spectator ions on either side of the equation are cancelled out leaving you with the minimum net ionic equation

Question 22

What does the term neutralisation deem in chemistry?

Answer 22

A neutralization reaction is when an acid and a base react to form water and a salt and involves the combination of H+ ions and OH- ions to generate water. The neutralization of a strong acid and strong base has a pH equal to 7.

Question 23

Describe a reversible reaction.

Answer 23

The reaction can occur in both directions

E.g CH3COOH -> CH3COO + H

Question 24

What is a spectator ion?

Answer 24

A spectator ion is an ion that exists as a reactant and a product in a chemical equation. These can be cancelled out from the equation.

Question 25

Define what is a standard solution.

Answer 25

A standard solution is a solution containing a precisely known concentration of an element or a substance. A known weight of solute is dissolved to make a specific volume.

Question 26

Define and state Henry’s law.

Answer 26

Henry’s law - the solubility of a gas in a liquid is proportional to the pressure of the gas over the solution.

In other words, the amount of dissolved gas is proportional to its partial pressure in the gas phase. The proportionality factor is called the Henry’s law constant.

Question 27

Crystallisation is?

Answer 27

Crystallization is also a chemical solid–liquid separation technique, in which mass transfer of a solute from the liquid solution to a pure solid crystalline phase occurs.

Question 28

Define the term miscible.

Answer 28

Of liquids - forming a homogeneous mixture when added together.
E.g. “sorbitol is miscible with glycerol”

Question 29

What is volatility?

Volatile and non-volatile matter

Answer 29

Volatility is the tendency of a substance to vaporize. Volatility is directly related to a substance’s vapor pressure. At a given temperature, a substance with higher vapor pressure vaporizes more readily than a substance with a lower vapor pressure

The term is primarily written to be applied to liquids; however, it may be used to describe the process of sublimation which is associated with solid substances, such as dry ice (solid carbon dioxide), which can change directly from the solid state to a vapor, without becoming liquid.

Question 30

What is solvation?

Answer 30

Also called dissolution, is the process of attraction and association of molecules of a solvent with molecules or ions of a solute. As ions dissolve in a solvent they spread out and become surrounded by solvent molecules.

Question 31

Noble gases are?

Answer 31

The noble gases are the chemical elements in group 18 of the periodic table.

They are the most stable due to having the maximum number of valence electrons their outer shell can hold.
Therefore, they rarely react with other elements since they are already stable.

Question 32

Describe the atomic radius.

Answer 32

Is a measure of the size of its atoms, usually the mean or typical distance from the center of the nucleus to the boundary of the surrounding cloud of electrons.

Low to high - top left hand corner to bottom left hand corner.
High to low - left hand side of table to right

Question 33

What is a valence shell electron?

Answer 33

The valence shell is the outermost shell of the atom.

The electrons in this shell may be able to move freely depending on the type of reactions

Question 34

What is ionisation energy?

Answer 34

Is qualitatively defined as the amount of energy required to remove the most loosely bound electron, the valence electron, of at atom to form a cation

Question 35

What is electron affinity?

Answer 35

Is defined as the amount of energy released when an electron is added to a neutral atom to form a negative ion - anion

Question 36

Define the term isoelectronic

Answer 36

2 or more atom, molecules or ions are isoelectronic with each other is they have the same number of electrons or a similar electron configuration and the same structure regardless of the nature of the elements involved.

Question 37

What is electronegativity?

Answer 37

Is a chemical property that describes the tendency of an atom of functional group to attract electrons towards itself.
It’s affected by both its atomic number and the distance at which its valence electrons reside from the charged nucleus.