chem chap 8 - acids and bases Flashcards
What is an acid?
A substance that produces hydrogen ions (H+) in aqueous solutions
What is the formulae of hydrochloric acid, nitric acid and sulfuric acid and what ions do they produce in aqueous solutions?
HCl, HNO3, H2SO4
Cl- NO3- SO4 2-
What are the 3 properties of acids?
Sour taste, acids dissolve in water to form solutions that conduct electricity and turns blue litmus paper red
What are the 3 reactions of acids?
acid + metal -> salt + hydrogen
acid + carbonate -> salt + water + carbon dioxide
acid + base -> salt + water
What are salts?
An ionic compound that can be obtained from acidic reactions
What salt is formed in a reaction involving sulfuric acid?
Sulfate
What salt is formed in a reaction involving nitric acid?
Nitrate
What salt is formed in a reaction involving hydrochloric acid?
Chloride
In the word equation: magnesium + dilute sulfuric acid → magnesium sulfate + hydrogen
Label the reactive metal, acid, cation, salt
Reactive metal: magnesium
Acid: dilute hydrochloric acid
Cation: magnesium
Salt: sulfate
What is the test for hydrogen gas?
Placing a burning splint at the mouth of the test tube, hydrogen gas extinguishes the burning splint with a “pop” sound
In this word equation: calcium carbonate + hydrochloric acid → calcium chloride + carbon dioxide + water
Label the carbonate, acid, cation and salt
Carbonate: calcium carbonate
Acid: hydrochloric acid
Cation: calcium
Salt: chloride
What is the test for carbon dioxide gas?
Bubbling the gas through limewater. Carbon dioxide gas forms a white precipitate with limewater
In this word equation: magnesium hydroxide + dilute nitric acid → magnesium nitrate + water
Label the reactant cation, hydroxide, product cation, salt
Reactant cation: magnesium
Hydroxide: magnesium hydroxide
Product cation: magnesium
Salt: nitrate
What is a base?
A metal oxide or hydroxide. They contain the oxide ion (O 2-) or the hydroxide ion (OH-)
What are the properties of a base?
Most bases are insoluble in water ( not alkalis)
When an acid reacts with a base, neutralisation reaction occurs
What are alkalis?
Bases that are soluble in water
A substance that produces hydroxide ions, OH-, in aqueous solutions
What are the properties of an alkali?
Taste bitter, feel slippery and soapy, dissolves in water to form solutions that conduct electricity, turn red litmus paper blue, when heated with ammonium salts give off ammonia gas, react with acids to form salt and water
What is the general equation of ammonium salts reacting with alkali
Alkali + ammonium salt → salt+ water+ ammonia gas
What is the test for ammonia gas?
Ammonia gas turns damp red litmus paper blue in alkali + ammonium salt solution
what colour would these indicators be in acidic solutions?
Methyl orange, screened methyl orange, litmus, thymolphtalein
Methyl orange: red
Screened methyl orange: violet
Litmus: red
Thymolphtalein: colourless
what colour would these indicators be in alkaline solutions?
Methyl orange, screened methyl orange, litmus, thymolphtalein
Methyl orange: yellow
Screened methyl orange: green
Litmus: blue
Thymolphtalein: blue
At what pH range which these indicators change colour?
Methyl orange, screened methyl orange, litmus, thymolphtalein
3 to 5, 3 to 5, 5 to 8, 9 to 10.5
At which numbers of the pH scale is acidic, neutral, alkaline
Acidic: 0 to 6
Neutral: 7
Alkaline: 8 to14
Describe the concentration of hydrogen ions and hydroxide ions in an acidic solution
More hydrogen ions than hydroxide ions
Describe the concentration of hydrogen ions and hydroxide ions in a neutral solution
Hydrogen ions equal to hydroxide ions
Describe the concentration of hydrogen ions and hydroxide ions in an alkaline solution
Less hydrogen ions than hydroxide ions
What happens when there are low pH values in soil?
There is a decrease inte uptake of phosphorus and potassium
Lack of phosphorus causes the leaves to turn dark green
Earn of potassium causes the leaves to turn yellow
What is ste typical pH level of soil
4 to 8: most plants grow best when soil is neutral or slightly acidic
Now does ph of soil become unsuitable for plants?
Too much fertiliser added to soil
Environmental pollution such as acid rain
How to control the pH of the soil?
Chemicals are often added to soil to adjust pH levels
Soil that is too acidic can be treated with bases such as slaked time (calcium hydroxide) other wise known as liming the soil
Calcium hydroxide reacts with the acid in the soil and increases the pH so that plants can grow healthily
What happens when too much calcium hydroxide is added to soil
The soil will be too alkaline which is unsuitable for plant growth
What are the properties of basic oxides (metal oxides)
Most are insoluble in water
Solids at room temperature
Read with acids to form salt and water
What are amphoteric oxides?
Metallic oxides that react with both acids and bases to form salts and water
In the word equation: hydrochloric acid + zinc oxide → zinc chloride + water, does the metal oxide, zinc oxide but as a basic oxide / base or acidic oxide / acid?
Basic oxide
In the word equation: sodium hydroxide + zinc oxide → sodium zincate + water, does the metal oxide, zinc oxide but as a basic oxide / base or acidic oxide / acid?
Acidic oxide
What are the properties of acidic oxides?
Most acidic oxides dissolve in water to form acids
Acidic oxides do not react with acids
What are neutral oxides
Non-metals that form oxides that show neither basic nor acidic properties
Are neutral oxides soluble in water?
Insoluble
This oxide reacts with acids but reacts with alkalis, what oxide is this?
Amphoteric
This oxide reacts with acids and does not react with alkalis, what oxide is this?
Basic oxides
This oxide does not react with acids but reacts with alkalis, what oxide is this
Acidic oxides
This oxide does not react with acids and does not react with alkalis, what oxide is this
Neutral oxide
