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HIGHER CHEMISTRY > UNIT 3 > Flashcards

UNIT 3 Flashcards

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1
Q

What are the three main environmental considerations of the chemical industry?

A

1) How can waste be minimized?
2) How can we avoid making toxic substances?
3) Can we design products that will biodegrade?

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2
Q

What is the most obvious step taken to reduce waste in a chemical process?

A

Recycling reactant is the most obvious step taken to reduce waste in a chemical process

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3
Q

How are industrial processes designed?

A

To maximize profit and minimize the impact on the environment.

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4
Q

What are the factors that influence the design of a chemical process?

A

Availability,sustainability and cost of feed stocks,opportunities for recycling, energy requirements,use of by products, product yield

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5
Q

What do environmental considerations include?

A

Minimizing waste, avoiding the use or production of toxic substances and designing products which will biodegrade.

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6
Q

What is percentage yield and write the formula for this.

A

The percentage yield is a simple way of comparing the amount of product actually obtained from a reaction with the amount expected.

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7
Q

What does a cost analysis do?

A

Compares the cost for producing the same quantity of product.

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8
Q

When can the percentage yield not be desired?

A

If the cost of the reactants is very expensive.

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9
Q

What is atom economy and what is the formula for this?

A

Atom economy is the proportion of reactants converted into desired product.

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10
Q

When is the concept of equilibrium applied?

A

It is applied to reversible reactions

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11
Q

When is a chemical reaction in state of equilibrium?

A

When the rate of the rate of the forward reaction is equal to the rate of the reverse reaction.

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12
Q

How can the equilibrium be altered?

A
  • Changing the concentration of reactants or products
  • Changing the pressure
  • Changing the temperature
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13
Q

What effect do catalysts have on the equilibrium position?

A
  • They have no effect

- They allow the reaction to reach equilibrium more quickly.

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14
Q

What is the enthalpy change?

A

The change in energy in a chemical reaction.

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15
Q

Why are chemists interested in enthalpy changes?

A

They can have health,safety and cost considerations.

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16
Q

What is the enthalpy of combustion?

A

It is defined as the enthalpy change when one mole of a substance is burned completely in oxygen.

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17
Q

Why are the values obtained different from the theoretical values?

A

Heat is lost to the surroundings

Incomplete combustion takes place.

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18
Q

State hess’s law

A

the enthalpy change of a chemical reaction is independent of the route taken.

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19
Q

Breaking bonds….energy

Making bonds…..energy

A

Requires

Releases

20
Q

What is a redox equation?

A

Combination of both reduction and oxidation reactions.

21
Q

What is an oxidizing agent?

What is a reducing agent?

A

An oxidising agent is a substance that accepts electrons

A reducing agent is a substance that donates electrons.

22
Q

Do reducing agents have low or high electronegativity values?

A

Low

23
Q

Do oxidizing agents have low or high oxidizing agents

A

high

24
Q

Do metals act as reducing or oxidizing agents?

A

Reducing

25
Q

Do non-metals act as reducing or oxidizing agents?

A

Oxidising

26
Q

Do metals have low/high electronegativity values?

Do non-metals have high/low electronegativity vlaues?

A

low

high

27
Q

What other compounds can cause oxidation or reduction reactions?

A

The permanganate ion is a powerful oxidizing agent

Carbon monoxide is a powerful reducing agent.

28
Q

Which elements/compounds on the electrochemical series are strong oxidising agents?

A

Ones at the bottom left.

29
Q

Which elemetns/compounds on the elctrochemical series are strong reducing agents?

A

Ones at the top right

30
Q

Write down the steps for solving more complex equations.

A

1) Check that the main element reacting(not oxygen) is balanced
2) Add water to balance oxygen atoms
3) Add hydrogen ions to balance the hydrogen atoms
4) Add electrons to the same side as the hydrogen ions so that both sides of the equation have the same change.

31
Q

What are the uses of some strong oxidising agents?

A

Oxidizing agents such as hydrogen peroxide is a highly effective bleach as it is able to break down colored compounds. It is found in teeth whitening products and hair products.
Hydrogen peroxide is an effective antiseptic and kills bacteria and fungi and destroys viruses.
Potassium permanganate is also used for its antiseptic properties. It is used in aquaria to destroy the bacteria and fungi that can infect fish.

32
Q

What is chromatography used for?

A

It is used to separate the components in a mixture.

33
Q

What is separation depend on?

A
  • The size of the molecules

- The polarity of the molecules

34
Q

‘A component can often be identified by how far it has traveled’. Explain this statement.

A

For example if is the paper chromatography was run using a non polar substance, then non polar components would be attracted to the hexane and would be expected to travel further up the paper than polar components.

35
Q

Name another form of chromatography and its use?

A

gas liquid chromatography. It is a technique used to separate mixtures in a gas phase.

36
Q

Retention time.

A

The length of time it takes a substance to reach the detector, in a chromatogram experiment,after being injected into the chromatography column.

37
Q

What is a standard solution?

A

A solution of known concentration

38
Q

What is an indicator?

A

It is a chemical dye added to a titration to detect the end point.

39
Q

What is a common example of a volumetric analysis?

A

An acid-alkali titration.

40
Q

Describe the process of making a standards solution

A

1) Accurately weigh solute
2) Dissolve in small amount of solvent,warming if necessary
3) Transfer into a standard flask
4) Rise all solution into flask with more solvent
5) Carefully make up to the mark
6) Insert stopper and shake

41
Q

Endpoint.

A

The point in a titration where the indicator changes color to indicate that the reaction is complete.

42
Q

Redox titrations

A

an experiment in which the volumes of aqueous solutions of a reducing agent and an oxidizing agent,which react together completely, are measured accurately. The concentration of one of the reactants can then be determined provided the concentration of the other reactant is know

43
Q

describe ways in which a gas can be collected

A

The gas syringe can be used for collecting both soluble and insoluble gases and has the advantage that it can measure the volume of gas produced
Collecting a gas by bubbling through water is only appropriate if the gas is insoluble in water and can only be used to measure the volume of the collecting vessel is graduated, such as an upturned measuring cylinder

44
Q

Rouge data

A

Results obtained from an experiment that are unusual/do not fit the pattern of expected results. usually caused by experimental error.

45
Q

A………. is more accurate than a measuring cylinder for measuring fixed volumes of liquid.

A

Pipette

46
Q

What can a burette be used for?

A

It can be used to measure non-standard volumes of liquid.

HIGHER CHEMISTRY (3 decks)

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