chemistry - acid and alkalis Flashcards
(29 cards)
Name several different indicators.
Blue/red litmus paper, red cabbage, methyl orange.
Define acid.
An acid is a substance with a pH lower than seven.
Define neutral.
A neutral is a substance that is nor acid or alkali, has a pH of seven.
Define neutralisation.
Neutralisation is a chemical reaction where an acid and a base react together. The result is usually water and a salt.
Define alkali.
An alkali is a substance which has a pH higher than seven.
Give two examples of an acid found in the lab.
Hydrochloric acid, sulfuric acid.
Give two examples of an alkali found in the lab.
Sodium hydroxide, potassium hydroxide.
Give one day-to-day example of a neutral.
Water.
List a common household acid.
Acetic acid = vinegar
Citric acid = lemon
List a common household alkali.
Bicarbonate = baking soda
What colour does litmus paper turn in acidic solutions?
Red.
What colour does litmus paper turn in alkaline solutions?
Blue.
What colour does litmus paper turn in neutral solutions?
Green.
Which colour does universal indicator turn in acidic solutions?
Red.
Which colour does universal indicator turn in alkaline solutions?
Blue.
Which colour does universal indicator turn in neutral solutions?
Green.
What is the equivalent of acid + alkali?
Salt + Water.
Which particular name does salt have?
Sodium chloride.
True or false: anything ending in “hydroxide” is an alkali.
True. However, very rarely, there are some alkalis which don’t end in “hydroxide”.
Why would charcoal be added to an experiment?
To remove the universal indicator.
Why would solutions be left to evaporate slowly overnight when making salt?
To make crystals.
Fresh milk has a pH of 6. How do you think the pH will change as it becomes sour?
It will become more acidic, will have a lower pH scale.
Which substance would be most alkaline out of orange juice, egg white, oven cleaner and milk?
Oven cleaner.
How do you prepare a natural indicator?
Crush berries (add water), add juice to acid and alkali samples, see if colour changes.
