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Flashcards in Amount of substance Deck (44)
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1

What is a mole?

The amount of substance in grams that has the same number of particles as there are atoms in 12 grams of carbon 12.

2

What is relative atomic mass?

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

3

What is relative molecular mass?

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

4

How can you use the Avogadro's constant to calculate the number of particles?

Number of particles = Number of moles * Avogadro's constant

5

What is the Avogadro constant?

One mole contains 6.022*10^23 particles

6

How do you calculate the number of moles?

Moles = mass/relative molecular mass

7

What is the Ideal Gas equation?

pV = nRT

8

How do you convert temperature to Kelvin?

Kelvin = degrees centigrade + 273

9

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

cm^3 = dm^3 /1000

10

How do you convert from cm^3 to m^3?

cm^3 = m^3 /1000000

11

How do you convert from dm^3 to m^3?

dm^3 = m^3 /1000

12

What is the concentration of a solution?

The number of moles dissolved per 1dm^3.

13

How do you calculate the number of mole using the concentration and volume of the solution?

Number of moles = concentration * volume/1000

14

What are the units for the concentration of a solution?

mol dm^3

15

What is the empirical formula?

The simplest ratio of atoms of each element in a compound

16

What is the molecular formula?

The actual number of atom of each element in a compound
Made up of a whole number of empirical units

17

What is the theoretical yield?

The mass of product that should be formed in a chemical reaction

18

What is the actual yield?

The mass of product formed after the reaction and is always less than the theoretical yield

19

Why is the actual yield always less than the theoretical yield?

Not all the starting chemicals react fully
Some chemicals are lost

20

How do you calculate the percentage yield?

Percentage yield = Actual yield/theoretical yield * 100

21

What does the percentage yield tell us?

Percentage yield tells us how wasteful a process is as it is based on how much product is lost during the process

22

What is the atom economy?

Atom economy is a measure of the efficiency of a reaction

23

How do you calculate the atom economy?

%Atom economy = molecular mass of desired product/sum of molecular masses of all reactants * 100

24

Why do companies in the chemical industry try to use high atom economies?

High atom economy processses are better for the environment as there is less waste

25

Why are high atom economy processes more sustainable?

They make more efficient use of raw materials

26

Why are high atom economy processes less expensive?

Companies will spend less money on separating the desired product from the waste products

27

What do titrations allow you to do?

Titrations allow you to work out the concentration of an acid or alkali

28

Describe how you would find the concentration of an alkali or acid from a titration.

-Accurately pipette 25cm^3 of alkali into conical flask
-Touch the surface of the alkali with pipette
-Add a few drops of the appropriate indicator
-Fill a burette with a standard solution of acid using a funnel at eye level
-add the acid into the alkali whilst swirling the mixture
add the acid dropwise at the endpoint
-Repeat the experiment to get 2-3 concordant results

29

What is a standard solution?

A solution that has a known concentration

30

What are the two main indicators for acid/alkali?

Methyl orange
Phenolphthalein