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Chemistry Higher > Unit 3 > Flashcards

Unit 3 Flashcards

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1
Q

In the chemical industry how do you reduce costing

A

Employment
Raw material alternative
Operating conditions

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2
Q

Maximise profit and minimise impact on environment

A

Reducing pollution- recycle where possible
Process design; availability, sustainability and cost of feedstock
Environmental- minimise waste, avoid production of toxic waste and design biodegradable products (if possible)

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3
Q

Atom economy

A

Atom economy is a measure of percentage of reactant atoms which are converted into the desired product of a chemical reaction

% atom economy = mass if desired products/
total mass of reactants X 100

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4
Q

Percentage yield

A

Quantity of desired product

% yield= actual/Theo X 100

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5
Q

Equilibrium

A

A state of balance in which nothing changes

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6
Q

Rules of equilibrium

A
  1. The concentration of reactant and products remain constant
  2. The concentrations are usually NOT equal
  3. The reaction has not stopped
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7
Q

Factors that affect the equilibrium

A

> concentration
temperature
pressure

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8
Q

Concentration

A

Reactants; increase- right
Decrease-left

Products; increase- left
Decrease- right

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9
Q

Temperature

A

Exothermic [-]
Increase-left

Decrease-right

Endothermic [+]

Increase- right

Decrease- left

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10
Q

Pressure

A

GASES ONLY

Increase- moves to the side with less gas

Decrease- moves to the side with more gas

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11
Q

Catalyst in equilibrium

A

This does not change the position of the equilibrium

However it does speed up the rate of reaction

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12
Q

Exothermic

A

Products Less energy than reactants

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13
Q

Endothermic

A

Products More energy than reactants

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14
Q

Equilibrium and Industry

A

The laws of the equilibrium are used by industrial chemicals to increase the yield of products

Example- Haber process

Reaction conditions;
Catalyst- iron
Temp- 450 degrees (moderate temp)
Pressure- 200 atmospheres (high pressure)

Forward reaction = exothermic
Backwards reaction= endothermic

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15
Q

Enthalpy

A

The enthalpy of combustion is the energy released to the surroundings when 1 mole of a substance is burned completely in oxygen

Enthalpy = CM🔺T

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16
Q

Bond enthalpy

A

Break bonds- endothermic [+]

Form bonds- exothermic [-]

17
Q

Active complex

A

An intermediate state that is formed during the conversion of reactants into products
Higher the energy level the less stable

18
Q

Hess’s Law

A

The overall enthalpy change for any reaction is independent of the route taken

19
Q

Redox

A

Metals give away- oxidised ( MAO)

Non- mentals take- reduction (NTR)

20
Q

Displacement

A

A metal higher in the electrochemical series will displace a Lowe metal from a solution if its ions

21
Q

Reducing agent

A

Donates electrons

As a reducing agent loses electrons it becomes oxidised

Group one are best reducing agents
Lithium

22
Q

Oxidising agents

A

Accepts electrons

As oxidising agents gain electrons they become reduced

Group seven are best oxidising agents
Fluorine

23
Q

Chromatography

A

Method of separating and analysing a mixture of soluble chemical

24
Q

Uses of chromatography

A

To follow the course of a chemical reaction

To identify additives in foods

To identify finger prints at a crime scene

25
Q

Paper chromatography

A

Capillary action the solvent moves up the paper

Can move quickly or slowly

Two stages; mobile phase and stationary phase

26
Q

Rf value

A

Rf= distance moves by the compound

Distance moved by the solvent

27
Q

Standard solution

A

Is a solution containing precisely known concentrations of an element or substance

28
Q

Evaporation

A

A solvent can be removed from a solution by heating the solution in an evaporating basin

29
Q

Filteration

A

Is used to collect an insoluble solid from a solid/liquid mixture

30
Q

Methods for collecting gas

A

Collecting gas over water can be used for gases that are NOT very soluble

An upturned measuring cylinder should be I. Place of the gas jar

The gas syringe can be used for both soluble and insoluble gases: more accurate as you can read scale on syringe. Although limit to how much gas can be collected

31
Q

Titration

A

Used to determine quantity or concentration of a reactant

Chemistry Higher (1 decks)

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