Acids and Bases

Year 10Year 10

What are Acids?What are Acids? Acids are commonAcids are common Some are Some are

dangerous and dangerous and can burn your skincan burn your skin

Some are safe to Some are safe to eat and drinkeat and drink

Stomach acid Stomach acid helps digest foodhelps digest food

explosion

AcidsAcids

Definition Definition • A group of compounds which behave similarlyA group of compounds which behave similarly• All have low pHAll have low pH• Turn Litmus paper REDTurn Litmus paper RED• All donate HAll donate H++ ions in aqueous solution ions in aqueous solution

ExamplesExamples• Hydrochloric HClHydrochloric HCl• Sulfuric HSulfuric H22SOSO44

• Nitric HNONitric HNO33

• Ethanoic CHEthanoic CH33COOHCOOH

AcidsAcids

A A dilute aciddilute acid has lots of water and a has lots of water and a small amount of acidsmall amount of acid

A A concentrated acidconcentrated acid has lots of acid has lots of acid and not much water so must be and not much water so must be handled carefullyhandled carefully

A A strongstrong acid releases lots of H acid releases lots of H++

A A weakweak acid releases fewer H acid releases fewer H++

What are Bases (Alkalis)?What are Bases (Alkalis)?

In our home we In our home we often use bases often use bases to clean things. to clean things. Eg Bleach and Eg Bleach and toothpastetoothpaste

Some things are Some things are not acids or not acids or bases, we say bases, we say that they are that they are neutral. Eg Waterneutral. Eg Water

BasesBases

DefinitionDefinition• A family of compounds that behave A family of compounds that behave

similarlysimilarly• Have a high pHHave a high pH• Turn litmus BLUETurn litmus BLUE• All donate OHAll donate OH--

ExamplesExamples• Ammonia NHAmmonia NH33

• Sodium Hydroxide NaOHSodium Hydroxide NaOH

Measuring acid strength?Measuring acid strength?

To decide if something is an acid or a To decide if something is an acid or a base we can use an indicator.base we can use an indicator.

Litmus and Universal Indicator are Litmus and Universal Indicator are examples of indicators.examples of indicators.

They change colour depending on if They change colour depending on if they are in an acid or a base.they are in an acid or a base.

Working with IndicatorsWorking with Indicators

Red litmus turns BLUE in the Red litmus turns BLUE in the

presence of Basespresence of Bases Blue litmus turns RED in the Blue litmus turns RED in the

presence of acidpresence of acid Acids and bases react together in Acids and bases react together in

a NEUTRALISATION reactiona NEUTRALISATION reaction

Acid ReactionsAcid Reactions

Acid + Base Acid + Base Salt + Water Salt + Water

Acid + Metal Acid + Metal Salt + Hydrogen Salt + Hydrogen

Acid + Carbonate Acid + Carbonate Salt + Water + Carbon Dioxide Salt + Water + Carbon Dioxide

• Hydrochloric acids (HCl) form CHLORIDE saltsHydrochloric acids (HCl) form CHLORIDE salts

• Nitric acid (HNONitric acid (HNO33) forms NITRATE salts) forms NITRATE salts

• Sulfuric acid (HSulfuric acid (H22SOSO44) forms SULFATE salts) forms SULFATE salts

Acid RainAcid Rain

Consider Consider • Causes Causes

naturalnatural humanhuman

• Effects Effects buildingsbuildings floraflora faunafauna healthhealth

• Chemical equationsChemical equations• Prevention/SolutionPrevention/Solution

Testing GasesTesting Gases

Hydrogen -Hydrogen -

Testing GasesTesting Gases

Hydrogen - POP TESTHydrogen - POP TEST

• Explodes with a squeaky popExplodes with a squeaky pop

Carbon Dioxide – Carbon Dioxide –

Testing GasesTesting Gases

Hydrogen - POP TESTHydrogen - POP TEST

• Explodes with a squeaky popExplodes with a squeaky pop

Carbon Dioxide – Limewater goes Carbon Dioxide – Limewater goes

cloudycloudy

Oxygen – Oxygen –

Testing GasesTesting Gases

Hydrogen - POP TESTHydrogen - POP TEST

• Explodes with a squeaky popExplodes with a squeaky pop

Carbon Dioxide – Limewater goes Carbon Dioxide – Limewater goes

cloudycloudy

Oxygen – Relights a glowing splintOxygen – Relights a glowing splint

Antacid InvestigationAntacid Investigation

NZ facts 2007NZ facts 2007

• 70% population get 70% population get

heartburn /GERDheartburn /GERD

• $9m on 1 brand!$9m on 1 brand!

• 33rdrd most widely most widely

prescribed medicineprescribed medicine

Which brand is the Which brand is the

best?best?

Identify Unknown SolutionsIdentify Unknown Solutions

Rates of ReactionRates of Reaction

Factors increasing the rate of Factors increasing the rate of reactionreaction

•Surface areaSurface area•ConcentrationConcentration•TemperatureTemperature•Catalyst/EnzymeCatalyst/Enzyme•PressurePressure

Metals/periodic tableMetals/periodic table

, Element, compound, exo/endo, Element, compound, exo/endo