Atoms and reactions module 2.1 Flashcards
define relative atomic mass
the weighted mean mass of an atom of an isotope compared with 1/12 of the mass of an atom of carbon-12.
why do different isotopes of the same element react in the same way?
because chemical reactions involve electrons which isotopes have the same number. neutrons make no difference to chemical reactivity
what is the formula to find the relative atomic mass ?
Ar=(relative isotopic mass x percentage abundance) + relative isotopic mass x percentage abundance) / 100
What is the gas equation at room temperature and pressure
n= volume/24
Define empirical formula
The simplest whole number ratio of atoms of each element in the compound
Anhydrous
Substance that contains no water molecules
Define hydrated compounds ?
The crystalline compound containing water molecules
Water of crystallisation definition
Water molecules that form n essential part of the crystalline structure of a compound
What are two types of crystals ?
Hydrated and anhydrous
What is the main difference between strong acids and weak acids ?
Strong acids are fully disossiciates whereas weak acids are partially dissociates
What do we make when we react a acid with a metal carbonate ?
Salt,carbon dioxide and water
alkalis
- give out OH- ions when dissolved in water
What do we make when a alkali reacts with a acid ?
- salt and water
What is a oxidising agent ?
Chemical they accepts electrons
What is a reducing agent ?
Chemicals that donate electrons
isotopes
atoms of the same element with different numbers of neutrons and therefore different masses
relative isotopic mass
the mass compare with 1/2th mass of carbon-12
relative isotopic mass
the mass compare with 1/2th mass of carbon-12
why do some transition meal ions have f=roman numerals?
- they form more than one ion with different charges so the oxidation number is shown by the roman numerals.
formulae of nitrate
NO3-
formulae of carbonate
C03 2-
formulae of sulphate
SO4 2-
formulae of hydroxide
OH-
formulae of ammonia
NH4+
formulae of a zinc ion
Zn2+
Acid + carbonate
Salt,carbon dioxide and water
Acid + metal oxide
Salt + water
Acid + alkali
Salt + water
Acid + metal
Salt + hydrogen
Reason for not a 100% perventage yield
- reaction may be at equilibrium and may not go to completion
- side reactions may lead to by- prouducts
- some of reactant or product may be left behind in the apparatus
- prouct loss
Salts
Any chemical compound formed from an acid when a H+ ion from the acid had been replaced by a metal ion or another positive ion e.g ammonium ion
Acid salts
- one H+ ion is replaced not all.
- still behaves as an acid as the remaining H+ ion can be replaced
Base
- H+ acceptors,neutalise acods
Oxidation number of oxygen in peroxides
-1
Oxidation number of hydrogen in metal hyrdroxides
-1
Kpa to Pa
x 1000
Dm3 to m3
/ 1000
Cm3 to m3
/ 1000000
How to work out percentage yield
- find the amount of mole in the limiting reagent ( if not given find moles in all reactants smallest mole number is limiting)
- use the equation (mole ratio) to find the amount of moles expected in the product ( theoretical yield)
- divide actual/ theoretical x100
What does a high atom econmy mean
- less waste/ bu- products made
Sulfuric acid
- H2SO4
Nitric acid
- NH03
Ethanoic acid
CH3COOH
Dative covalent bonding
One atom supplies both the shared electrons in a covalent bond
Ionic lattice
Repeating pattern
Oppositely charge ions
