C8 Acids, bases and salts - 1 & 2 Flashcards
What is an acid?
An acid is a substance that dissolves in water to produce hydrogen. - positively charged hydrogen ions H^+.
pH below 7.
What are examples of acids?
Hydrochloric acid (stomach) and citric acid.
What is a base?
A base is a substance that dissolves in water to produce hydroxide (ions).
OH^-
What are alkalis?
Alkalis are bases that are dissolved in water.
What are examples of bases?
Calcium carbonate (limestone) and sodium chloride (salt).
What does the pH scale show?
The pH scale shows how acidic an object is.
0-6 is acidic.
7 is neutral.
8-14 are bases.
What test can we use to investigate whether a substance is acidic or basic?
We can use the litmus paper test.
What is litmus paper?
Litmus paper is a thin strip of paper which comes in colours of blue and red.
Explain the litmus paper test.
Dip the litmus paper in the solution you want to test it. RED = ACIDIC.
BLUE = BASIC.
Litmus paper comes in both red and blue so there is still a result even if it stays those colours.
What is another acid-alkali indicator?
Another acid-alkali indicator is the universal indicator. The universal indicator turns different colours based on substances’ pH values.
What colours does the universal indicator turn?
It will turn red-yellow shades when tested with ACIDS.
It will turn purple-blue shades when tested with ALKALIS.
What can acids do?
Acids can neutralise a base, forming a salt and water.
Do all metals react with acids?
No, not all metals will react with acids. Only metals that are more reactive than hydrogen.
What two products are formed in a reaction with acids and metals?
Salt and hydrogen.
What reaction occurs with acids and metals? -MASH
MASH:
Metal + acid => salt + hydrogen
What may we observe during a reaction between a metal and acid?
You may observe fizzing which is the hydrogen gas. - introduce lit splint to reaction. If a “squeaky pop” occurs, it is hydrogen.
How to test for hydrogen gas?
The test for hydrogen gas is using a lit splint and if the gas burns with a “squeaky pop”, hydrogen is present.
What happens when a metal (magnesium) react with hydrochloric acid?
magnesium + hydrochloric acid => magnesium chloride + hydrogen
What salts does sulfuric acid produce?
Sulfuric acid produces sulphate salts.
What salts does nitric acid produce?
Nitric acid produces nitrate salts.
What salts does hydrochloric acid produce?
Hydrochloric acid produces chloride salts.
What type of bases can acids react with?
Acids will react with bases:
-Metal oxides
-Metal hydroxides
In the neutralisation reaction (acid and base), what two products are formed?
Water and salt.