Acids, Alkalis and Indicators Flashcards
Describe the pH scale
The pH scale goes from 0 to 14, 0 being the most acidic and 14 being the most alkaline. The lower the pH the more acidic and the higher the pH, the more alkaline. 7 is a neutral pH as it is in the middle of the pH scale.
What are indicators
Indicators are substances that change colour depending on pH. Universal indicator contains a mixture of different indicators, therefore it produces a range of colours depending on the pH
What is the colour of Litmus in alkaline
Blue
What is the colour of Methyl orange in alkaline
Yellow
What is the colour of phenolphthalein in alkaline
Pink
What is the colour of Litmus in acid
Red
What is the colour of Methyl orange in acid
Red
What is the colour of phenolphthalein in acid
Colourless
When acids dissolve in water, what do they produce an excess of
Hydrogen ions ( h+)
When alkalis dissolve in water, what do they produce an excess of
Hydroxide ions( OH-)
What does it mean when there is a concentration of hydrogen ions in a substance
It is more acidic and has a lower pH
What does it mean when there is a concentration of hydroxide ions in a substance
It is more alkaline and has a higher pH
What does concentration mean
The amount of solute ( usually measured in grams) dissolved in a certain volume of solvent.
What does dissociate mean
Break up
What is the formula for concentration
Concentration ( g/ dm^3) =
Volume of solution (dm^3)
How do you convert cm^3 to dm^3
Cm^3 to dm^3 = Divide 1000
How do you convert dm^3 to cm^3
Dm^3 to Cm^3 = Multiply 1000
What does a dilute solution mean
Contains only small amounts of dissolved solute per unit volume
What does a concentrated solution mean
Contains a lot of dissolved per unit volume
What happens to pH when H+ ions increase by a factor of 10
pH decreases by 1
What happens to pH when H+ ions decrease by a factor of 10
pH increases by 1
What are strong acids
Strong acids fully dissociate when they dissolve in water. This produces high concentrations of H+ ions and therefore a lower pH value
What are weak acids
Weak acids only partially dissociate when they dissolve in water. This means not all of their molecules will be split, so only a low concentration of H+ ions is produces, therefore a higher pH
