Acids Flashcards
What substance is used to distinguish between acids and alkalis
Litmus paper
What is the pH scale
The pH scale goes from 0 – 14 (extremely acidic substances can have values of below 0)
All acids have pH values of below 7, all alkalis have pH values of above 7
The lower the pH then the more acidic the solution is
The higher the pH then the more alkaline the solution is
A solution of pH 7 is described as being neutral
What is universal indicator
Universal indicator is a wide range indicator and can give only an approximate value for pH
It is made of a mixture of different plant indicators which operate across a broad pH range and is useful for estimating the pH of an unknown solution
A few drops are added to the solution and the colour is matched with a colour chart which indicates the pH which matches with specific colours
What happens when acids are added to water
When acids are added to water, they form positively charged hydrogen ions (H+)
The presence of H+ ions is what makes a solution acidic
What happenes when alkalis are added to water
When alkalis are added to water, they form negative hydroxide ions (OH–)
When alkalis are added to water, they form negative hydroxide ions (OH–)
What is a neutralisation reaction
A neutralisation reaction occurs when an acid reacts with an alkali
When these substances react together in a neutralisation reaction, the H+ ions react with the OH– ions to produce water
What is titration
Titrations are a method of analysing the concentration of solutions
What are acid based titrations
Acid-base titrations are one of the most important kinds of titrations
They can determine exactly how much alkali is needed to neutralise a quantity of acid – and vice versa
Name some of the steps of titration
Use the pipette and pipette filler and place exactly 25 cm3 sodium hydroxide solution into the conical flask
Place the conical flask on a white tile so the tip of the burette is inside the flask
Add a few drops of a suitable indicator to the solution in the conical flask
