4 - Chemical Changes Flashcards
What is the equation that links concentration moles and volume together in titration calculations, and what are the units? (TC CC Ch)
number of moles (mol) = concentration (mol/dm3) x volume (dm3)
How do you convert moles/dm3 into g/dm3 in titration calculations? (TC CC Ch)
You times the mol/dm3 vaule by the relative formula mass.
What do acids do in aqueous solutions? (SWA CC Ch)
release H+ ions
and ionise (split)
What does aqueous mean? (SWA CC Ch)
Dissolved in water
What is the word for when an acid molecule splits to leave H+ ions? (SWA CC Ch)
ionisation
What are some examples of strong acids? (SWA CC Ch)
- Hydrochloric acid (HCl)
- Sulphuric acid (H2SO4)
- Nitric Acid (HNO3)
What are stong acids? (SWA CC Ch)
acids that fully ionise in aqueous solutions
What feature of an equation indicates that the acid has fully ionised in aqueous solution - stong acid? (SWA CC Ch)
When the arrow of the equation is only pointing one way - towards the products
What feacture of an equation indicates that the acid only partially ionises in aqueous solution - weak acid? (SWA CC Ch)
a double arrow - one pointing towards the the products and one towards the reactants.
This is called a reversable arrow.
What do weak acids do in aqueous solution? (SWA CC Ch)
Only partially ionise - only some of the molecules ionise.
What are some examples of weak acids? (SWA CC Ch)
- carbonic acid
- ethanoic acud
- citric acid
What does the pH scale give us an idea of? (SWA CC Ch)
the concentration of hrdrogen ions
How high are strong acids pHs compared to that of weak acids? (SWA CC Ch)
strong acids have a lower pH than weak acids for a given concentration.
Why do strong acids have a greater concentration of hydrogen ions? (SWA CC Ch)
Because they fully ionise in solution meaning that there are more hydrogen ions made from the splitting of the acid molecules
By how much does the concentration of hydrogen ions increase when the pH scale decreases by one unit? (SWA CC Ch)
the concentration of hydrogen ions increase by ten times
What do scientists call it when there is a ten times distance between the two numbers on the pH scale? (SWA CC Ch)
one order of magnitude
What does the concentration of an acid tell us? (SWA CC Ch)
this tells us the amount of acid molecules in a given volume of solution
If a solution has fewer acid molecules in a given volume, does that mean that the strength of the acid decreases? (SWA CC Ch)
No it does not. a dilute acid will have fewer acid molecules in a given volume than a concentrated acid even if the strength of the acid is the same.
