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3s and 4s Clevedon Science > C3 > Flashcards

C3 Flashcards

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1
Q

What are the common units for measuring reaction rate?

A

(g/s for mass loss and cm3/s for gas made)

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2
Q

When HCl reacts with marble chips what would you measure if you were trying to work out the reaction rate?

A

Volume of gas given off at specific time intervals

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3
Q

Why does the rate of a reaction slow down as the reaction continues?

A

As the reaction goes on the reactant particles are being used up.

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4
Q

What is a catalyst ?

A

A catalyst is a chemical used in small amounts and specific to one reaction that changes reaction rates without being used up.

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5
Q

Explain how changing surface areas affects reaction rates.

A

Increasing the surface area increases the rate of the reaction.

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6
Q

Explain why airborne powders can be dangerous in factories.

A

Powdered substances have an incresed surface area and therefore will react very quickly.

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7
Q

Explain in terms of collisions how changing surface area affects reaction rate.

A

Greater surface area means there will be more surfaces available for the particles to collide.

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8
Q

Calculate relative formula mass for Calcium Sulphate

A

96 + 40 = 136g

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9
Q

Use the relative formula mass of Magnesium Oxide to show and explain why mass is conserved during a reaction.

A

2Mg + 02 = MgO (48g+ 32g = 80g)

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10
Q

Calculate the mass of Sodium Chloride produced when excess HCl reacts with 23g of sodium.

A

The limiting factor is the sodium as the acid is in excess.

From the equation 1 mole of sodium gives 1 mole of salt. 23g of sodium is equal to 1 mole of salt.

1 mole of NaCl is 58.5g

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11
Q

Calculate relative formula mass for Calcium Sulphate

A

136g

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12
Q

Calculate relative formula mass for formulae Calcium Nitrate

A

Ca(N03)2

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13
Q

calculate relative formula mass for formulae Magnesium sulphate

A

MgSO4

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14
Q

calculate relative formula mass for formulae Calcium Nitrate

A

Ca(N03)2

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15
Q

calculate relative formula mass for formulae Calcium Oxide

A

CaO

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16
Q

Explain in terms of reacting particles why temperature affects reaction rate.

A

The reactant particles move more quickly; they have more energy. The particles collide more often, and more of the collisions are successful and hence the rate of reaction increase.

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17
Q

Describe what a reaction rate graph would lool like if the temperature was increased.

A
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18
Q

Explain in terms of reacting particles why concentration affects reaction rate

A

The reactant particles become more crowded; there is a greater chance of the particles colliding and the rate of reaction increases.

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19
Q

Describe what a reaction rate graph would lool like if the concentration was increased.

A
20
Q

How do you calculate perecentage yield?

A

Percentage yield = actual yield/predicted yield × 100

21
Q

How might you decrease your yield?

A

Filtering, evaporating, transferring liquids and sometimes not all reactant reacts to make the product.

22
Q

How do you calulate atom economy?

A

Atom economy = Mr of desired products/sum of Mr of all products × 100

23
Q

Explain why industry wants a high atom economy.

A

To reduce unwanted products and increase sustainability.

24
Q

What is an exothermic reaction?

A

These are reactions that transfer energy to the surroundings. The energy is usually transferred as heat energy, causing the reaction mixture and its surroundings to get hotter.

25
Q

What is an endothermic reaction?

A

These are reactions that take in energy from the surroundings. The energy is usually transferred as heat energy, causing the reaction mixture and its surroundings to get colder.

26
Q

Describe an experiment where you could measure the energy given out by a fuel.

A
27
Q

Explain why a reaction is exothermic or endothermic using energy changes during bond making and breaking.

A

Energy is absorbed to break bonds. Bond-breaking is an endothermic process. Energy is released when new bonds form. Bond-making is an exothermic process.

Whether a reaction is endothermic or exothermic depends on the difference between the energy needed to break bonds and the energy released when new bonds form. In endothermic reactions more energy is absorbed than the energy released. In exothermic reactions more energy is released than is absorbed.

28
Q

What is the formula for calulating the energy transferred in a reaction.

A

Energy transferred (joules, J) = mass of water heated (grams, g) × 4.2 × temperature rise (ºC)

29
Q

How do you calculate the energy per gram?

A

energy released (J/g of fuel) = energy transferred to water (J) ÷ mass of fuel burned (g)

30
Q

Explain why batch processing is used to make drugs, but continuous processing for ammonia

A

A chemical that is needed in a small amount or only as needed (a speciality chemical) is usually made by a batch process. Production does not go on all the time. A chemical that is needed in a large amount is usually made by a continuous process. Production goes on all the time.

31
Q

Why is development of new drugs expensive?

A

Research and testing, labour costs, energy costs ,raw materials, time taken for development and marketing make new drugs expensive to make and develop. It typically takes around twelve years and over £500 million to do this.

32
Q

Describe how chemicals can be extracted from plants.

A

Several steps are needed to extract chemicals from plants. These include: crushing to break open the plant material, boiling and dissolving in a suitable solvent and chromatography to separate the different chemicals in the plant.

33
Q

Explain why is it difficult to test and develop new pharmaceutical drugs that are safe to use.

A

Pharmaceutical drugs need to be thoroughly tested before they can be licensed for use. They are tested in a laboratory to check that they are not toxic, and later they are trialled using human volunteers. At this point, any potential side effects should show themselves. Most substances do not pass all the tests and trials, so drug development is expensive and takes a long time.

34
Q

Explain why diamond, graphite and fullerenes are allotropes

A

Carbon has different forms or ‘allotropes’, including diamond, graphite and fullerenes. Allotropes are forms of an element that exist in the same state (solid, liquid or gas) but have different properties because their atoms are arranged differently.

35
Q

What does the structure of diamond look like?

A
36
Q

Describe the structure and bonding in diamond.

A

Diamond has a giant molecular structure. Each carbon atom is covalently bonded to four other carbon atoms. This makes diamond’s melting point and boiling point very high.

37
Q

Why dooes diamond not conduct electricity.

A

There are no free electrons or ions in diamond, so it does not conduct electricity.

38
Q

Why does diamond have a high melting and boiling point?

A

A lot of energy is needed to separate the atoms in diamond. This is because covalent bonds are strong, and diamond contains very many covalent bonds.

39
Q

What does the structure of graphite look like?

A
40
Q

Describe the structure and bonding in graphite.

A

Graphite has a giant molecular structure. Each carbon atom is only covalently bonded to three other carbon atoms. Graphite contains layers of carbon atoms. The layers slide over each other easily because there are only weak forces between them, making graphite slippery.

41
Q

Why can graphite conduct electricity?

A

Graphite contains delocalised electrons (free electrons). These electrons can move through the graphite, carrying charge from place to place and allowing graphite to conduct electricity.

42
Q

What does bukminster fullerene look like?

A
43
Q

How many carbon atoms are there bonded in a bucky ball?

A

60

44
Q

What is a nanotube?

A

Nanotubes are fullerenes that can be used to reinforce graphite in tennis rackets because they are very strong. They are also used as semiconductors in electrical circuits.

45
Q

Explain why fullerenes can be used in new drug delivery systems.

A

The nanotube’s structure allows it to be used as a container for transporting a drug in the body. A molecule of the drug can be placed inside the nanotube cage. This keeps the drug ‘wrapped up’ until it reaches the site where it is needed. In this way, a dose that might be damaging to other parts of the body can be delivered safely to, for example, a tumour.

46
Q

Explain why nanotubes enable them to be used as catalysts.

A

Nanotubes have a massive surface area for their size. Spreading a catalyst, atom by atom, on the surface of a nanotube provides a huge surface area of catalyst for reactants to come into contact.

3s and 4s Clevedon Science (9 decks)

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