Chemistry topic3 Flashcards
What is red litmus paper used to test for?
Alkalis
What colour does red litmus paper turn if alkali is added
Blue
What is blue litmus paper used to test for?
Acids
What colour does blue litmus paper turn when an acid is added..?!
Red
What ion causes acidity?
The hydrogen ion - H+
the pH scale is a measure of the ? of hydrogen ? in a solution and hence its ?
concentration,ions, acidity
what does pH stand for
p stands for Potenz (meaning power in German) and H stands for H+
what type of a scale is the pH scale?
a logarithmic scale
what does pH being a logarithmic scale mean
it means a solution of pH 1 has 10 times as many hydrogen ions than a solution with a pH of 2
What are the two main ways of finding the pH of a solution?
By using a universal indicator
By using a pH meter
There are 6 main acids, what are they
Hydrochloric acid, nitric acid, sulphuric acid, phosphoric acid, ethanoic acid and carbonic acid
Give the chemical formula of phosphoric acid
H3PO4
Give the chemical formula of ethanoic acid
CH3COOH
Give the chemical formula for carbonic acid
H2CO3
What happens when a metal and an acid combine?
A salt is formed
give the balanced chemical equation for the reaction between magnesium and hydrochloric acid
Mg + 2HCl —> MgCl2 + H2
What are the products of a reaction between a metal and an acid
A halide is formed with the hydrogen in the acid replaced with the metal, leaving left over hydrogen eg: MgCl2 + H2
? of acids are made by dissolving certain covalent ? in ? the water causes the ? molecules to break ? in a way that generates ? ions
solutions, molecules, water, covalent, apart, hydrogen
What does concentrated and dilute refer to in acids
The amount of acid molecules dissolved in water!! x
Will a concentrated acid have a large or little amount of acid molecules dissolved in a certain volume of water?
Large because it is concentrated meaning lots of particles all in the same volume in comparison to dilute where there’s a lot less particles
What are the two words for acid molecules getting split apart
1.Dissociation
2.Ionisation
What does strong and weak refer to in acids
How many of the acid molecules have been split apart into ions
What three acids are the main strong acids?
HCl, H2SO4 and HNO3! x
What will happen to a strong acid when dissolved in water
It will compeltely dissociate into ions - so all the acid molecules will split apart and form hydrogen ions
What happens when a weak acid dissolved in water
only a small proportion of the molecules dissociate into ions - so lots of undissociated moleculesss and a low number of ions
Which acid is a weak acid?
Ethanoic acid
What does the reversible arrow mean?
It shows that a reaction cannot go to completion because not all molecules are dissociated
Example of ethanoic acid and the reversible arrow
CH3COOH reversible arrow CH3COO- + H+, this shows how it is incomplete because not all of the ions have been dissociated so the arrow shows this
bases are ? that can ? acids
substances, neutralize
bases are normally metal ? or metal ?
oxides, hydroxides
alkalis are ? which are soluble in ? - so they are a ? group of bases
bases, water, sub
Alkalis are generally what?
Hydroxides