How Much? (not Maths) Flashcards
Give an example of a reversible reaction
Thermal decomposition of ammonium chloride
What are food additives?
Substances that are added to improve the quality of food
What methods can be used to amylose the colours in food?
Paper chromatography and mass spectrometry
How does paper chromatography work?
A spot of colour is put onto paper and a solvent is allowed to move through the paper the colours move distances depending on their solubility
Why are modern instrumental methods of analysis often used?
They are very:
rapid
Accurate
Sensitive
What are the DisAds of instrumental analysis?
Equipment is very expensive and special training is required to use it
What is a reversible reaction?
When the products of a chemical reaction can react to reform the products
How may you identify the Compounds in a sample?
Gas chromatography
What happens in gas chromatography?
The mixture is carried by a gas through a long column each compound travels at different speeds leaving the column at different times. Their retention times are recorded which can be compared to indenting the compounds
What is the main purpose of the gas chromatography column in GC-MS analysis?
To separate the compounds in the mixture
What can a mass spectrometer give?
The relative molecular mass of a compound
What is the peak called?
The molecular ion peak
The individual compound with the peak with the largest mass corresponds to what?
The ion with just on electron removed
How is the relative molecular mass shown in a mass spectrum?
From the molecular ion peak or the peak with the largest mass (furthest to the right of the spectrum)
Why is it not usually possible to get 100% yield from a chemical reaction?
Reactions may not go to completion, other reactions may happen, some product may be lost when separated or collected
Why should chemical manufactures use reactions with high yield?
To help conserve resources, reduce waste and pollution
What is the yield of a chemical reaction?
How much is actually made
Why do we only count protons and neutrons to calculate the mass number of an atom?
The mass of an electron is very small compared to that of a proton or neutron
How many protons neutrons and electrons are there in an atom of
19
F
9
9 protons
9 electrons
10 neutrons
What are isotopes?
Atoms of the same element of atoms with the same atomic proton numbers that have different numbers of neutrons
What is a mole?
The relative atomic mass of an element in grams
What do we compare the masses of all the other atoms with?
Carbon-12
What is the mass of 1 mole of sodium atoms?
23g
Why is the relative mass of chlorine not a whole number?
It has 2 main isotopes and the relative atomic mass is an average value
What is the empirical formula?
The simplest ratio of the atoms or ions in a compound
