Unit 2: 3 - How Much? Flashcards
What is the relative mass of protons and neutrons?
1
What do we call the total amount of protons and neutrons in an atom?
Its mass number
What do we call the total amount of protons in the atom?
The atomic (or proton) number
In a neutral atom, how many electrons are there compared to protons?
The same amount
What is the name given to an atom with an irregular number of neutrons?
An isotope
What is the relative charge of each of the 3 components of an atom?
Proton +1 Neutron 0 Electron -1
What is the relative mass of an electron?
0
What do we call an atom with a positive or negative charge?
An ion
What is special about some isotopes?
There are unstable and radioactive?
What is a mole?
The relative atomic mass in grams.
What is the relative atomic mass and its symbol?
The Ar is the relative mass of 1 atom of the element.
What is the relative molecular mass and its symbol?
The Mr is the total sum of all the Ars in the atom.
How do you work out the percentage of mass used by a single element in a molecule?
(Total number of that element * Relative atomic mass of the element) / Relative molecular mass (*100)
What is the empirical formula?
The simplest ratio of the atoms or ions in a compound. For example, the molecular formula of ethane is C2H6 but its empirical formula is CH3.
How do we work out a more complicated empirical formula? E.g. What is the empirical formula when 3.2g of sulfur reacts with oxygen to make 6.4g of sulfur oxide? (The atomic mass of sulphur is 32g and oxygen is 16g
What is the yield of a chemical reaction?
The yield is how much you make.
What is the percentage yield?
The percentage yield compared the amount made with the amount that could be made.
How do we calculate the percentage yield?
(Amount of product collected / Maximum amount of product possible) *100
Why is it not usually possible to get the maximum yield from a reaction?
Reactions may not be fully completed, other reactions might happen and some product may be lost when separated or collected.
Why should chemical manufacturers use reactions with high yields?
To waste as little energy as possible, making production more sustainable and reducing pollution.
What is a reversible reaction?
A reaction which can go both ways.
What is an example of a reversible reaction?
Heating ammonium chloride.
Give 2 methods used to analyse chemicals in food.
Paper chromatography and mass spectrometry
What is gas chromatography?
When the mixture is carried up by a gas through a long column packed with particles of a solid. The individual compounds travel at different speeds and come out at different times. The retention times can be compared with the results known for other compounds to help identify the compounds in the mixture.
