1.2 amounts of substance part 2 Flashcards

1
Q

what does stoichiometry tell you

A

the relative number of moles of reactant and products involved in a reaction

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2
Q

what is stoichiometry found from

A

the balanced equation

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3
Q

what is volumetric analysis used for

A

to find the volume of one solution which is needed to react with a measured volume of another solution

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4
Q

what can the results of volumetric analysis be used to find

A

the unknown concentration of one of the solutions

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5
Q

what is the solution with the known concentration called

A

the standard solution

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6
Q

the 4 steps to making a standard solution:

A

dissolve known mass of solid in de-ionised water

using a funnel, transfer into a volumetric flask; include washings

make up to the graduated line by carefully adding de-ionised water, making sure the meniscus sits on the line

stopper the flask and invert to mix the contents thoroughly

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7
Q

how to find the concentration of a solution of base

A

fill a burette with a known concentration of the acid

pipette a known volume of base into a conical flask

add a few drops of indicator to the base in the flask

add the solution of the acid from the burette until the indicator just changes colour- known as end point

record volume of acid added to nearest 0.05cm cubed
perform a rough titration and then sufficient accurate ones until the titres are concordant (within 0.01cm cubed of eachother)

calculate the mean titre from concordant titres to 2 d.p.

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8
Q

what colour is methyl orange in acid

A

red

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9
Q

what colour is methyl orange in base

A

yellow

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10
Q

what is methyl orange’s end point colour

A

orange

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11
Q

what colour is phenolphthalein in acid

A

colourless

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12
Q

what colour is phenolphthalein in base

A

pink

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13
Q

what is phenolphthalein’s end point colour

A

colourless

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14
Q

What are acid base titration calculations used for

A

To find the concentration of a solution of the volume of solution which reacts

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15
Q

What is a hydrated salt

A

A salt which contains water

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16
Q

What happens when hydrated salts are heated

A

The water is driven off and the compound is said to be anhydrous

17
Q

What does waters of crystallisation refer to

A

The water molecules which form an essential part of the crystalline structure of a hydrated salt

18
Q

How to calculate the number of moles of water of crystallisation

A
  • you will need to know the masses of the hydrated and anhydrous salts
  • mass of water = mass of hydrated salt - mass anhydrous salt
  • work out the number of moles of anhydrous salt and of water
  • find the simplest whole number ratio
19
Q

What is percentage yield

A

A measure of the success of a laboratory preparation

20
Q

How to work out percentage yield

A

Actual yield of product/theoretical yield of product x 100

21
Q

Do both values need to be in moles for the percentage yield formula

22
Q

What is theoretical yield

A

The number of moles expected if the reactants were completely converted into products

23
Q

How to work out theoretical yield

A

Calculating the number of moles of reactants used and then using the balanced equation to calculate the number of moles of product if the yield was 100%

24
Q

What is actual yield

A

The actual number of moles of product formed in the reaction

25
What is atom economy
A measure of the efficiency of a reaction in terms of the atoms involved
26
What does atom economy consider
Desired product and by products
27
Atom economy equation
Mr of desired product/sum of Mrs of all products x 100
28
What can atom economy be calculated from
The balanced equation
29
What is atom economy's significance in terms of the environment
Lots of waste products
30
Addition reaction
Have an atom economy of 100%- one product made
31
Substitution and elimination reactions
Have an atom economy of less than 100%- at least 2 products made
32
What is sustainable chemistry
The design of chemical products and processes that reduce the use of hazardous substances and generation of waste
33
What does sustainability mean
Developing industrial processes that prevent the depletion of the earths natural resources
34
Rules for chemical sustainability
1. Reduce use of hazardous chemicals 2. Reduce amount of waste 3. Recycle waste 4. Use fewer chemicals 5. Design for energy efficiency i.e. Use s catalyst and renewable energy resource 6. Use renewable feedstocks 7. Manufacture biodegradable products 8. Think safety 9. Establish international cooperation
35
What are the downsides of green chemistry
1. Cost- research = people = £ 2. Reduction of land needed for food 3. Adhering to international agreements