2 Acids, alkalis and titrations Flashcards
What tells you how acidic or how alkaline a solution is?
The pH scale.
What does the pH scale range from?
0 to about 14.
What is 7 on the pH scale?
Neutral.
What is an example of a substance with a pH of 7?
Sodium chloride solution.
What are the properties of those with pH values descending from 7?
Increasingly acidic.
What are the properties of substances with values ranging from 0-3?
This is the range for hydrochloric acid. And it is strongly acidic.
What are the properties of substances with values ranging from 4-6?
This is the range for vinegar.
And it is weakly acidic.
What is another word for vinegar?
Ethanoic acid.
What are the properties of those with pH values ascending from 7?
Increasingly alkaline.
What are the properties of substances with values ranging from 8-10?
This is the range for ammonia solution.
And it is weakly alkaline.
What are the properties of substances with values ranging from 11-14?
This is the range for sodium hydroxide solution. And it is strongly alkaline.
What do you have to remember when writing pH?
It is a small p and a big H. The big H is the symbol for Hydrogen.
How can you measure pH?
- Using universal indicator.
- Acid-Alkali indicators.
What is the universal indicator?
Universal indicator is made from a mixture of indicators, which change colour in a gradual way over a range of pH values.
What are the two types of universal indicator?
It can be used as a solution or as paper.
What is the most common form of universal indicator?
It is known as full-range universal indicator.
How does the full-range universal indicator work?
It changes through a variety of colours from pH 1 right up to pH 14, but isn’t very accurate.
How do you match the specific colour to its corresponding pH?
The colour of the paper or solution is checked against a chart to find the pH.
What colours represent acidity when using the universal indicator?
Red, orange, yellow, light green.
Which colour represents neutrality when using the universal indicator?
Green.
What colour represents alkalinity when using the universal indicator?
Dark green, blue, purple.
What are acid-alkali indicators?
Any substance that has different colours depending on the pH can be used as an indicator.
How many common indicators are there?
5.
What is the first common indicator?
Litmus.
What colour does litmus turn when in presence of an acid?
Red.
What colour does litmus turn when in presence of an alkali?
Blue.
What colour is litmus when in the presence of neutrality?
Purple, which is an equal mixture of the red and blue forms.
What is the second common indicator?
Methyl orange.
What colour does methyl orange turn when in presence of an acid?
Red.
What colour does methyl orange turn when in presence of an alkali?
Yellow.
What is the third common indicator?
Phenolpthalein.
What colour does phenolphthalein turn when in presence of an acid?
Colourless.