Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Chemistry > C6- Chemical Synthesis > Flashcards

C6- Chemical Synthesis Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Chemistry flashcards Periodic Table flashcards Chemistry 101 flashcards Organic Chemistry 101 flashcards
1
Q

Examples of tested products?

A
  • Food additives- the chemical industry produces additives like preservatives, colourings and flavourings for food producers.
  • Cleaning and decorating- like paints contain pigments and dyes which have been developed by chemists. Cleaning products like bleach also have been tested.
  • Drugs- the pharmaceutical industry. They have gone through development and testing before use.
  • Fertilisers- Fertilisers contain ammonia, which is produced by the chemical industry.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Chemical- scale?

A
  • Some chemicals are produced on a massive scale- for example over 150 million tonnes of sulphuric acid are produced around the world each year.
  • Sulphuric acid has loads of different uses. For example, in car batteries.
  • Other chemicals e.g. Pharmaceuticals are produced on a smaller scale because we need less of them.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Chemical- Sectors??

A
  • In the UK the chemical industry makes up a significant chunk of the economy.
  • In the UK there are over 200 000 people employed in the chemical industry.
  • Some chemicals are sold directly to customers. While others are sold to other industries as raw materials for other products.
  • The pharmaceutical industry has the largest share of the industry.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

pH scale??

A

(Look up a pic of it)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Acidic compounds?

A

Pure acidic compounds can be solids.

For example, citric acid which is used as a food additive and tartaric acid.

Acidic compounds can be liquid.

For example, sulphuric acid, nitric acid and ethanoic acid which is the acid in vinegar.

Acidic compounds can be gases.

For example, hydrogen chloride.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Common alkali?

A

Common alkali include sodium hydroxide (used in cleaning products like bleach)

Potassium hydroxide (used in alkaline batteries)

And calcium hydroxide (used to neutralise acidic soils)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Indicators and pH meters?

A
  • Indicators contain a dye that changes colour depending on whether its above or below a certain pH.
  • Litmus paper is used to find out if a solution is acidic or alkaline- if it’s red the solution is acidic and blue if it’s alkaline.
  • Universal indicator is useful for the combination of dyes. It is used to estimate the pH of a solution.
  • pH meters can measure the pH of a substance. This usually consists of a probe which is dipped into the substance and a meter which gives the reading of the pH.
  • pH meters are accurate than indicators.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Neutralisation reactions?

A
  • An acid is a substance with a pH of less than 7. Acidic compounds produce aqueous hydrogen ions in water.
  • An alkali is a substance with a pH of greater than 7. Alkaline compounds produce aqueous hydroxide ions in water.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What does an acid and an alkali make?

A

An acid and alkali react together to form salt and water. The products are neutral.

So it’s a neutralisation reaction.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Equation for neutralisation reaction?

A

Acid + Alkali→ Salt+ Water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Neutralisation reaction with ions?

A

Neutralisation can be seen as H+ and OH- ions. The hydrogen ions from the acid react with hydroxide ions from the alkali to make water (which is neutral)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Acid reacting with metal?

A

Acid + Metal → Salt+ Hydrogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Acid reacting with metal experiment?

A
  • The more reactive the metal the faster the reaction will go. Very reactive metals (sodium) react explosively.
  • Copper does not react with dilute acids at all because it’s less reactive than hydrogen.
  • The speed of reaction is indicated by the rate at which the bubbles of hydrogen are given off.
  • The hydrogen is confirmed by the burning splint test giving the notorious “squeaky pop”.
  • The name of the salt produced depends on which metal is used and which acid is used.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Metal oxides and metal hydroxides react with acid?

A

Acid+Metal Oxide →Salt+ Water

Acid+Metal Hydroxide→Salt+Water

These are neutralisation reactions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Metal carbonate give what??

A

Acid + Metal Carbonate→ Salt+ Water+ Carbon Dioxide.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

1st stage of chemical synthesis?

A

• Choosing the reaction- Chemists need to choose the reaction to make the product.

For example:

  • neutralisation- an acid and an alkali react to produce a salt.
  • thermal decomposition- heat is used to break up a compound into simpler substances.
  • precipitation- an insoluble solid is formed when two solutions are mixed.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

2nd stage of chemical synthesis?

A

• Risk assessment- the process could cause injury.

  • identifying hazards
  • assessing who might be harmed
  • deciding what action can be taken to reduce the risk.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

3rd stage of chemical synthesis?

A

• Calculating the quantities of reactants.

This included maths and a balanced symbol equation.

Using equations chemists can calculate how much of each reactant is needed to produce a certain amount of product.

This is important to the industry because you need to know how much each raw material is needed so there’s no waste.

As waste costs money.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

4th stage of chemical synthesis?

A

• Choosing the apparatus and conditions.

The reaction needs to be carried out using suitable apparatus and in the right conditions.

The apparatus needs to be the correct size and strength.

Whether a catalyst should be used is decided.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

5th stage of chemical synthesis?

A

• Insulating the product.

After the reaction is finished the products may need to be separated from the reaction mixture.

This could involve evaporation (if the product was dissolved)

It could include filtration (if the product is an insoluble solid)

And drying (to remove water)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

6th stage of chemical synthesis?

A

• Purification.

As you are isolating the product your helping to purify it. Crystallisation can be useful in the purification process.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

7th stage of chemical synthesis?

A

• Measuring yield and purify.

This yield tells you the overall success of the process.

It compares what you think you should get with what you get in practice. The purity of the chemical also needs to be measured.

23
Q

Filtration?

A
  • Used to separate an insoluble solid from a liquid.
  • Filtration can be used if the product is an insoluble solid that needs to be separated from a liquid reaction mixture.
  • It can be used in purification.
24
Q

Evaporation and crystallisation?

A
  • Used to separate a soluble solid from solution.
  • Heating up the solution causes the solute to evaporate leaving behind solid crystals of the product.
  • This is useful for purifying the product. The crystals have a regular structure that the impurities can’t fit into.
  • This process is often repeated over and over to improve the purity. Products are dissolved and then crystallised again. Which is called recrystallisation.
25
Q

Drying?

A
  • Used to dry the product by removing excess liquid.
  • The product can be dried in a drying oven.
  • Some heat the sample. Some blow hot,dry air over the product.
  • Products are also dried using desiccators. These are containers that contain chemicals like silica gel that remove water from their surroundings. They help to keep the product dry.
26
Q

Actual yield?

A

This is the mass of pure dry product. It depends on the amount of reactants you started with.

This actual yield is calculated by weighing the dried product.

27
Q

Theoretical yield?

A

This is the maximum possible mass of pure product that could have been made using the amounts of reactants you started with.

28
Q

Percentage yield?

A

This is the actual yield of the product as a percentage of the theoretical yield.

The percentage yield will always be less than 100%. This is because some product will be lost along the way through purification , etc.

29
Q

Percentage yield equation?

A

Percentage yield= actual yield (grams) / theoretical yield (grams) * 100

30
Q

Titrations?

A
  • They can be used to check the purity of acidic or alkaline products.
  • They work using neutralisation reactions.
31
Q

How to use titrations and burettes?

A
  • Add a known volume of alkali to a titration flask along with two or three drops of indicator.
  • Fill a burette with the acid.
  • Using the burette add the acid to the alkali a bit at a time. Giving the conical flask a regular swirl so the acid and alkali combine completely.
  • Go slow when you think the end point (colour change) is about to be reached so that no more acid is added than is necessary to neutralise the alkali.
  • The indicator changes colour when all the alkali has been neutralised.
  • Record the volume of acid used to neutralise the alkali.
32
Q

What’s a burette?

A

They measure different volumes and let’s you add the solution drop by drop.

33
Q

Solids in a titrations?

A
  • Titrations can’t be carried out with solids- only liquids.
  • So any solid alkali or acid being tested needs to be made into a solution.
  • If the substance is a solid lump you crush it into powder.
  • Put a titration flask onto a balance.
  • Weigh some of the powder into the flask. (The amount of solid will differ from substance to substance)
  • Add a solvent used (i.e water or ethanol) to dissolve the powder. (The amount of solvent will also differ)
  • Swirl the titration flask until all of the solid has dissolved.
34
Q

Purity equation?

A

% purity= calculated mass of substance / mass of impure substance at start * 100

35
Q

Mass equation?

A

Mass = concentration * volume

36
Q

Exothermic reaction?

A

An exothermic reaction is one which gives out energy to the surroundings. Usually in the form of heat and shown by an increase in temperature.

37
Q

Endothermic reaction?

A

An endothermic reaction is one which takes in energy from the surroundings. Usually in the form of heat and shown by a decrease in temperature.

38
Q

Energy level diagrams?

A
  • Energy level diagrams show the energy levels of the reactants and the products in a reaction.
  • In a exothermic reaction the products are at a lower energy than the reactants.
  • The difference in height represents the energy given out in the reaction.
  • In a endothermic reaction the products are at a higher energy than the reactants.
  • The difference in height represents the energy taken in during the reaction.
39
Q

Energy management?

A
  • If a chemical synthesis reaction is exothermic the heat produced has to be removed, otherwise the temperature of the reaction mixture will increase.
  • If the temperature increases, the rate of the reaction will also increase and the reaction mixture will get even hotter.
  • If the reaction mixture gets too hot when some of the reactants or products could become gases, which would increase the pressure and could cause an explosion.
  • If the reaction is endothermic heat needs to be provided otherwise the reaction mixture will become too cold.
  • This could slow down the rate of the reaction or cause the reaction mixture to freeze. This could damage equipment or stop the whole process.
40
Q

Reactions at different rates?

A
  • The rate of a chemical reaction is how fast the reactants are changed into products.
  • One of the slowest is rusting of iron.
  • Other slow reactions are chemical weathering (i.e. Acid rain)
  • Burning is a fast reaction but explosions are faster and release more gas.
41
Q

Why does the rate of reaction need to be controlled?

A
  • Safety- if the reaction is too fast it could cause an explosion which could be dangerous.
  • Economic reasons- changing conditions can be costly.

However, a faster rate means more product will be produced in less time. Companies have to choose optimum conditions that give low production costs. But this may mean compromising on the rate of production or the yield.

42
Q

Graphs for rate of reaction?

A

• The quickest reactions have the steepest lines and become flat in the least time.

An increased rate could be due to;

  • increase in temperature
  • increase in concentration
  • catalyst added
  • solid reactant crushed up into smaller pieces.
43
Q

What 4 things does rate of reaction depend on?

A
  • Temperature
  • Catalyst
  • Concentration
  • Size of lumps (surface area)
44
Q

Increase in temperature?

A

When the temperature is increased the particles all move faster.

If they are moving faster, they collide more frequently.

Also the faster they move the more energy they have, so more of the collisions will have enough energy to make the reactions happen.

45
Q

Increase concentration?

A

If a solution is made more concentrated it means there are more particles of reactant knocking about in the same volume of water. (Or solvent)

This makes collisions between the reactant particles more likely.

46
Q

More surface area?

A

If one of the reactants is a solid then breaking it up into smaller pieces will increase its surface area.

This means the particles around it will have more area to work on so there will be collisions more frequently.

47
Q

Catalyst?

A

A catalyst is a substance which increases the speed of a reaction without being changed or used up in the reaction.

A catalyst works by giving the reacting particles a surface to stick to where they can bump into each other- increasing the number of successful collisions.

48
Q

Rate of reaction equation?

A

Rate of reaction= amount of reactant used or amount of product formed / time

49
Q

How can speed of reaction be measured?

A
  • Precipitation and change in colour.
  • Change in mass
  • The volume of gas given off
50
Q

Precipitation and colour change?

A
  • This is when the product of the reaction is coloured or is a precipitate which clouds the solution.
  • If a precipitate is formed you can observe a mark through the solution and measure how long it takes for it to disappear. The faster the mark disappears the quicker the reaction.
  • This only works for reactions where the initial solution is see through.
  • If the reactants are coloured and the products are colourless (vice versa) you can time how long it takes for the solution to lose or gain its colour.
  • The results are very subjective- different people might not agree over the exact point when the mark “disappears” or the solution changes colour.
51
Q

Change in mass?

A
  • Measuring the speed of a reaction that produces a gas can be carried out using a mass balance.
  • As the gas is released the mass disappearing is easily measured on the balance.
  • The quicker the reading on the balance drops the faster the reaction.
  • Rate of reactions graphs are useful to plot results from this method.
  • This is the most accurate method, as the mass balance is very accurate.
  • But the disadvantage is that it releases gas straight into the room.
52
Q

The volume of gas given off?

A
  • This involves the use of a gas syringe to measure the volume of gas given off.
  • The more gas given off during a given time interval the faster the reaction.
  • A graph of gas volume against time could be plotted to give a rate of reaction graph.
  • Gas syringes usually give volumes accurate to the nearest cm cubed. So they are accurate.
  • If the reaction is too vigorous you can blow the plunger out of the end of the syringe.
53
Q

The chemical industry make useful products?

A

Most of the products will have been carefully researched, formulated and tested by chemists.

Chemistry (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions