C2.3 Flashcards
What is the atomic number of an atom?
Number of protons.
What is the mass number of an atom?
Number of protons and neutrons.
How does the mass of an electron compare with the mass of a neutron or proton?
Electrons are much lighter.
What are isotopes?
Atoms of the same element with different numbers of neutrons.
Why don’t symbol equations tell us exactly what mass of each reactant to use in a chemical reaction?
Because atoms of different elements have different masses.
Which atom do we use as a standard to compare relative masses of elements?
Carbon-12
What is a mole?
Relative atomic mass in grass or relative formula mass in grams.
2HCl has two meanings. What are they?
Balanced and unbalanced.
What is the percentage yield of a reaction?
=amount of product produced/max amount of product possible
x100%
What are chemical factories designed by?
Chemical engineers.
What does a single arrow in a chemical equation mean?
Reversible reaction.
What does a double arrow in a chemical equation mean?
Reversible reaction can go in both directions.
Why does a neutral solution look purple with litmus solution?
Because it is a complex molecule which reacts with an alkali to form a different colour.
What is a food additive?
A substance that’s added to food to extend its shelf life or to improve its taste or appearance.
What is a technique used to identify food additives?
Paper chromatography.
What happens to the food colourings when you make a paper chromatography?
Some compounds in a mixture dissolve better than others in particular solvents.
What do you think has aided the development of instrumental methods of chemical analysis?
Modern instrumental methods because they’re important in fighting pollution.
Why are these methods important?
Fight pollution.
What are the main steps of analysing mixtures?
- separate the compounds using gas chromatography
- identified using of the many instrumental techniques
What does a mass spectrometer do?
Can identify unknown substances and can detect very small quantities in the sample.
What is a gas chromatography?
It has a gas moving through a column pack with a solid.
