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Chemistry SL > Unit 1 > Flashcards

Unit 1 Flashcards

1
Q

What are elements?

A

Elements are made from any kind of atom. They take part in chemical reactions where substances made in process involving energy change.

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2
Q

What are compounds?

A

2 or more elements that are chemically combined. In reactions atoms combined together

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3
Q

What are mixtures?

A

In mixtures, elements and compounds interspersed but not chemically combined. This means compounds of mixtures retain same characteristic properties.

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4
Q

What are homogenous mixtures?

A

Homogenous mixtures has uniform composition and properties throughout. EX: Air

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5
Q

What are heterogenous mixtures?

A

Non uniform composition, so its properties not same, often possible to see separate components in heterogenous but not homogenous mixture.

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6
Q

How do separating mixtures work?

A

Compounds retain individual properties in mixtures and can be separated easily, different techniques will take advantage of suitable difference in physical properties like boiling point between substances seperated

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7
Q

How do separating mixtures of solids work?

A

Differences is solubility used to separate solids, suitable solvent chosen to ensure only desired substance dissolved and not other impurities

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8
Q

How does filtration work?

A

Used to separate undissolved solid from mixture of solid and liquid solution:
1. Filter paper placed in filter funnel above beaker
2. Mixture of insoluble solid and liquid poured into filter funnel
3. Filter only allow small liquid particles to pass through in filtrate
4. Solid particles too large to pass through filter paper stays behind as residue

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9
Q

How does crystallisation work?

A

Used to separate dissolved solids from solution when solid more soluble in hot solvent than cold.
1. Solution heated allowing solvent to evaporate and leaving saturated solution behind
2. Test if solution saturated by dipping glass rod into solution
3. Allow to cool slowly as solids come out of solution as solubility decreases, crystals grow
4. Crystals collected by filtering solution with distilled water to remove impurities than allowed to dry.

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10
Q

How does distillation work?

A

Used to separate 2 or more liquids miscible with one another.
1. Solution heated to temp of substances with lowest boiling point
2. Substance rise and evaporate to vapur then pass through condenser then turning to liquid in beaker
3. All substance is evaporated and collected, leaving other components of mixture.
4. Separated once one mixture fully separated

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11
Q

How does paper chromatography work?

A

Used to separate substance that has different solubilities in given solvent
1. Pencil line drawn on chromatogram and spots of sample placed on it. Pencil used as ink would mix with sample
2. Paper then lowered into solvent container as baseline above level of solvent so sample not washed.
3. Solvent travels by capillary action taking coloured substance, this shows different components of dye.

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12
Q

What is thin layer chromotography?

A

Similar to paper chromatography but has different stationary phase. this is thin layer of inert substance supported on flat unreactive surface. Mobile phase is a solvent.

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13
Q

What is retardation factor values?

A

Extent of separation molecules in investigated samples depend on solubility in mobile phase and adhesion to stationary phase. Rf value used to quantify distance a component can travel relative to solvent front. Compounds calculated using measurements:
Rf value = Distance travelled by component / Distance travelled by solvent.

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14
Q

What is a mole?

A

Mole is a mount of substance that contains the same number of chemical species as there are atoms in exactly 12g of isotope carbon-12. Can be used to measure amount of substance, one mol containing any number of elementary entities given by Avogadro’s constant.

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15
Q

What is avogadro’s constant and its formula?

A

Value 6.02 x 10^23 particles per mole.
Mol = Mass of substance / molar mass

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16
Q

Avogadro’s constant applies to

A

1 mole - 6.02 x 10^23

Atom: Smallest species of an element

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17
Q

What is molar mass and its formula?

A

Mass of one mole of a species is called molar mass. Has units g/mol^-1. Molar mass = Mass of substance / Number of moles.

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18
Q

What is mass of molecule formula ?

A

Molar mass / Avogadro’s constant

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19
Q

What is number of particles formula?

A

Number of moles * Avogadro’s constant

Smaller the object, greater the number of items grouped together. Same situation for grouped atoms.

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20
Q

What are elementary entitites?

A

Electrons or other chemical particles such as formula unit. Represents simplest ratio of ions in ionic compound.

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21
Q

What is Avogadro’s constant usage?

A

Used to calculate number of atoms, molecules, ions or electrons. This allows for units to vary depending on type of elementary entity being calculated.

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22
Q

What is relative formula mass?

A

Elements represented by atoms but compounds contain 2 or more atoms bonded together. Atoms of different elements have mass relative to carbon 12 but when combined, mass of all atoms in formula added to calculate relative formula mass for compound.

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23
Q

Empirical formula?

A

Compounds composed of elements that combined in consistent ratio, known as law of properties. EX: 2 hydrogens and 1 oxygen.

Not all atoms have same mass, consideration of the mass of each element needed when determining percentage in compound.

24
Q

What is concentration of solution?

A

Is amount of solute dissolved to make 1 dm cubed of solution

25
Q

What is solute and solvent?

A

Solute is substance that dissolves in solvent to form solution
Solvent is often water

26
Q

What is concentrated solution?

A

Solution that has high concentration of solute

27
Q

What is dilute solution?

A

Solution with low concentration of solute

28
Q

How is concentration expresssed?

A
  • Moles per unit volume
  • Mass per unit volume
  • Parts per million
29
Q

What is concentration formula (moles per unit volume)

A

Number of moles of solute (mol) / Volume of solution (dm^3)

cm^3 -> dm^3 (divide by 1000)

30
Q

What is avogadro’s law?

A

Avogadro’s hypothesis states that equal volumes of different gases contain equal numbers of particles at the same temperature and pressure.
Avogadro’s law can be used to calculate the volumes of gases involved in reactions.

31
Q

What are stoichiometric relationships?

A

used to deduced amount volume of gaseous reactants and products. EX: Combustion of 50cm^3 of propane, Volume of oxygen needed 250cm ^3, 150cm^3 of CO2 formula. Uses ratio propane : oxygen : carbon dioxide (1:5:3)

32
Q

What is a solution?

A

Solution is a homogenous mixture of solute and solven

33
Q

What is aqueous solution?

A

Solution with water as solvent

34
Q

What is standard solution?

A

Used to find concentration of other solutions

35
Q

What is titration?

A

Used to find concentration of unknown solutions, known as volumetric analysis

36
Q

What is the concentration formula?

A

Moles of solute / Volume of solution

37
Q

Number of moles of gas formula?

A

Volume / Molar Volume

38
Q

What is a back titration?

A

Technique used to find concentration or amount of unknown substance indirectly. Carry out reaction with unknown substance and excess of further reactant such as acid. Reactant then analysed by titration and mole ratio used to deduce moles or concentration of substance.

39
Q

What is limiting reactants?

A

Runs our first in equation

40
Q

What is excess reactant?

A

Not completely used up in reaction

41
Q

What is theoretical yield?

A

The maximum amount of product that can be produced from a given amount of reactant

42
Q

Percentage yield formula?

A

Actual yield / Theoretical yield * 100

42
Q

What is Experimental Yield

A

The measured amount of product obtained from a reaction

43
Q

What is atom economy?

A

The atom economy of a reaction shows how many of the atoms used in the reaction becomes the desired product- rest is waste.

44
Q

Atom economy formula?

A

Molecular mass of desired product / Sum of molecular mass of all reactants

45
Q

What are efficient processes?

A

Efficient processes have high atom economies and are important to sustainable development
- They use fewer resources
- Create less waste

46
Q

What is The Kinetic Theory Of Matter

A
  1. The volume of the gas particles is assumed to be zero.
  2. The gas particles are in constant motion.
  3. The collisions of the gas particles with the sides of the container cause pressure.
  4. The particles exert no forces on each other (no IMF).
  5. The average kinetic energy is directly proportional to the Kelvin temperature of the gas.
47
Q

What are Properties of Gases

A

No definite shape
No definite volume
Very easily compressed
High rate of diffusion
Gas particles exert pressure on their surroundings

48
Q

What are Real Gases

A

An ideal gas exactly obeys the gas laws.
Real gases actually have attractive forces between them.
Real gases actually take up some volume.
A gas most behaves like an ideal gas at high temperatures and low pressures.

49
Q

What are molar gas volumes?

A

Gases in a container exert a pressure as the gas molecules are constantly colliding with the walls of the container

50
Q

Relationship and formula between volume and pressure?

A

volume of a gas was inversely proportional to the pressure applied. In other words, as pressure is increased, volume decreases.
P1V1 = P2V2

51
Q

Relationship and formula between temperature and volume

A

volume of a gas is directly proportional to the Kelvin temperature. In other words, if you increase the temperature, the volume increases.
T1 / V1 = T2 / V2

52
Q

Relationship and formula between temperature and pressure

A

He discovered that at constant volume, if you increase the temperature, the pressure increases.
T1P2 = P1T2

53
Q

Relationship and formula between volume and number of moles

A

So for a gas at constant temperature and pressure, the volume is directly proportional to the number of moles of a gas.
V1n2=n1V2

54
Q

Combined Gas Law formula?

A

P1V1 / T1 = P2V2 / T2

55
Q

Ideal gas law formula and units?

A

PV = nRT

R = 8.31
P= Pa
V= m^3

Chemistry SL (6 decks)

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