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Physical Chemistry > Unit 1: Section 2- Amount of Substance + RP1 > Flashcards

Unit 1: Section 2- Amount of Substance + RP1 Flashcards

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1
Q

How many particles are in a mole?

A

6x10^23

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2
Q

How can you calculate number of particles? (what equation)

A

no. of particles = no. of moles x Avogadro’s constant

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3
Q

What is the ideal gas equation? including units

A

pV=nRT

p=pressure (Pa)
V=volume (m^3)
n=no. of moles
R=gas constant (8.31)
T=temp (K)

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4
Q

How much volume does one mole of gas take up at room temperature and pressure?

A

24dm^3

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5
Q

What is a standard solution?

A

Any solution you know the exact concentration of

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6
Q

What colours do methyl orange show up in?

A

red in acid
yellow in alkali

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7
Q

What colours do phenolphthalein show up in?

A

colourless in acid
pink in alkali

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8
Q

What does a titration allow you to work out?

A

you can find the amount of acid needed to neutralise an alkali. using this, you can work out the concentration of the alkali

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9
Q

What is the empirical formula?

A

The simplest whole number ratio of atoms of each element in a compound

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10
Q

What is the molecular formula?

A

The actual number of atoms of each element in a compound. It is made up of a whole number of empirical units.

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11
Q

How can you calculate empirical formulas?

A

By getting the mass of each element or % by mass and dividing it by the Mr to get the number of moles
Then divide each mole value by the smallest mole value to work out mole ratio

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12
Q

What is theoretical yield?

A

The mass of product that should be formed in a chemical reaction, assuming no chemicals are lost in the process

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13
Q

Why is it possible to get over 100% atom economy?

A

You could be measuring another product as well, e.g. water

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14
Q

Why do companies choose processes with high atom economy? List three things.

A
  • better for environment as produces less waste
  • more sustainable (makes more efficient use of raw materials)
  • less expensive
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15
Q

RP 1- What is a standard solution?

A

A solution with a known concentration

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16
Q

RP1- Describe how you would make a standard solution

A
  1. measure the mass of solid required
  2. transfer this to a volumetric flask and rinse the remaining weighing bottle content
  3. add a volume of distilled water to dissolve the solid, swirl to mix
  4. then add more distilled water up to the line on the volumetric flask. invert multiple times to mix
17
Q

RP1- What is the weighing by difference technique

A

a method to weigh materials accurately
mass of substance= mass of weighing dish and substance- mass of dish after substance has been transferred

18
Q

RP1- What equipment is used to carry out a titration? (5)

A

Pipette
Pipette filler
Conical flasks
Burette
White tile

19
Q

RP1- How do you carry out a titration?

A
  1. fill the burette with reactant, and a conical flask with another reactant
  2. add a few drops of indicator to the conical flask
  3. open the burette tap and allow reactant to flow into the conical flask
  4. stop and record the final burette volume when there is a colour change
  5. repeat until you get concordant results, then calculate a mean titre
20
Q

RP1- Why are acid-base indicators used?

A

to detect when a reaction reaches completion, usually by the presence of a colour change

21
Q

RP1- What are concordant results?

A

titres that are within 0.1cm3 of each other

22
Q

Define mole

A

the amount of substance in grams that has the same number of particles as there are atom in 12 grams of carbon-12

23
Q

Define relative atomic mass

A

the average mass of one atom compared to one twelfth of the mass of one atom of carbon-12

24
Q

Define relative molecular mass

A

the average mass of a molecule
compared to one twelfth of the mass of one atom of carbon-12

25
Q

What is the density equation?

A

mass/ volume

26
Q

How do you convert cm^3 to dm^3?

A

divide by 1000

27
Q

What is the volume of 1 mole of any gas at room temperature?

A

24dm^3

28
Q

What is the percentage yield equation?

A

actual yield/ theoretical yield x 100

29
Q

How do you calculate percentage uncertainty?

A

+/-
uncertainty/ measurement made on apparatus x100

Physical Chemistry (9 decks)

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