chemistry - acids and alkalis
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- Created by: laila.noor
- Created on: 17-02-21 12:27
how does phenolphthalein distinguish between acidic and alkaline solutions?
alkaline - pink
acidic - colorless
acidic - colorless
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how does methyl orange distinguish between acidic and alkaline solutions?
alkaline - yellow
acidic - red
acidic - red
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how does litmus solution distinguish between acidic and alkaline solutions?
alkaline - blue
acidic - red
acidic - red
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how does litmus paper distinguish between acidic and alkaline solutions?
alkaline:
blue litmus = stays blue
red litmus = turns blue
acidic:
blue litmus = turns red
red litmus = stays red
blue litmus = stays blue
red litmus = turns blue
acidic:
blue litmus = turns red
red litmus = stays red
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what does the pH scale measure and how can it be measured?
pH scale measures the acidity and alkalinity of a solution
pH can be measured using universal indicator of a pH probe
pH can be measured using universal indicator of a pH probe
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how to figure out if a solution is acidic, neutral or alkaline looking at the pH scale
pH scale < 7 = acidic
pH scale 7 = neutral
pH scale > 7 = alkaline
pH scale 7 = neutral
pH scale > 7 = alkaline
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what is the use of universal indicator to measure the approximate pH value of an aqueous solution?
add a couple of drops of solution to a piece of universal indicator paper and observe what color it goes (compare to pH scale)
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what source is acids and alkalis in aqueous solutions?
acids produce H+ ions in aqueous solutions
alkalis produce OH- ions in aqueous solutions
H+ = hydrogen ions
OH- = hydroxide ions
alkalis produce OH- ions in aqueous solutions
H+ = hydrogen ions
OH- = hydroxide ions
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what is neutralization?
a neutralization reaction is between an acid and a base (alkalis can neutralize acids)
ionic equation:
H+(aq) + OH-(aq) -> H2O(l)
ionic equation:
H+(aq) + OH-(aq) -> H2O(l)
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what is the equipment needed to carry out a titration?
pipette = accurately measure the volume of a reactant before transferring into a conical flask
burette = used to add varying measured volumes of solution
suitable indicator = substance that has different colors
burette = used to add varying measured volumes of solution
suitable indicator = substance that has different colors
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how to carry out a titration?
1. use pipette and pipette filler to add measured volume of alkali to a conical flask
2. add few drops of indicator and put conical flask on white tile
3. pour acid into burette and note starting volume
4. slowly add the acid to the alkali and swirl the c
2. add few drops of indicator and put conical flask on white tile
3. pour acid into burette and note starting volume
4. slowly add the acid to the alkali and swirl the c
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what is a concordant titre?
titres within 0.20cm3 (or 0.10cm3) of each other
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how do you find the mean titre?
(reading 1 + reading 2 + reading 3....)
------------------------------------------
the number of concordant titre
------------------------------------------
the number of concordant titre
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what equipment is needed to carry out a copper sulfate experiment?
measuring cylinder
beaker
glass rod
evaporating basin
spatula
filter
conical flask
water bath
Bunsen burner
beaker
glass rod
evaporating basin
spatula
filter
conical flask
water bath
Bunsen burner
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what are acids and alkalis in copper sulfate?
copper oxide = alkali
sulfuric acid = acid
sulfuric acid = acid
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how is the copper sulfate experiment carried out?
1. put sulfuric acid in conical flask and warm it in water bath
2. add spatula of copper oxide to sulfuric acid, stir with glass rod
3. add copper oxide until excess
4. filter mixture to remove copper oxide
5. pour filtrate into evaporating basin
6. heat
2. add spatula of copper oxide to sulfuric acid, stir with glass rod
3. add copper oxide until excess
4. filter mixture to remove copper oxide
5. pour filtrate into evaporating basin
6. heat
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what are the results from the copper sulfate experiment?
blue and regularly shaped salts
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what are the general rules for predicting the solubility of ionic compounds in water?
sodium = soluble
potassium = soluble
ammonium = soluble
nitrates = soluble
chlorides = soluble, except silver, lead
sulfates = soluble, except lead, barium, calcium
carbonates = insoluble, except sodium, potassium, ammonium
hydroxides = insoluble, except
potassium = soluble
ammonium = soluble
nitrates = soluble
chlorides = soluble, except silver, lead
sulfates = soluble, except lead, barium, calcium
carbonates = insoluble, except sodium, potassium, ammonium
hydroxides = insoluble, except
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what are acids and alkalis called in terms of proton transfer?
acids donate protons (H+)
bases accept protons
bases accept protons
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what are acids and bases?
acid = proton donors
bases = proton acceptors
bases = proton acceptors
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describe the reactions of HCl, H2SO4 and HNO3 with metals, bases and metal carbonates to form salts?
acid + base -> salt + water
acid + metal -> salt + hydrogen
acid + metal carbonate -> salt + water +carbon dioxide
acid + metal -> salt + hydrogen
acid + metal carbonate -> salt + water +carbon dioxide
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know that metal oxides, metal hydroxides and ammonia can act as bases, and that alkalis are bases that are soluble in water?
example of the use of ammonia as a base:
HCl + NH3 ->NH4Cl
alkalis: bases which are soluble in water
HCl + NH3 ->NH4Cl
alkalis: bases which are soluble in water
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what is the test for hydrogen?
test: ignite gas with lint splint
result: creates a 'squeaky pop' sound
result: creates a 'squeaky pop' sound
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what is the test for oxygen?
test: take a glowing splint and place it in a sample of gas
result: splint relights in oxygen
result: splint relights in oxygen
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what is the test for carbon dioxide?
test: bubble gas through the limewater
result: limewater turns cloudy
reason: because calcium carbonate forms
result: limewater turns cloudy
reason: because calcium carbonate forms
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what is the test for ammonia?
test: hold a piece of damp universal indicator paper or red litmus paper at the mouth of the test tube
result: ammonia turns the paper blue
result: ammonia turns the paper blue
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what is the test for chlorine?
(chlorine is a toxic gas)
(chlorine is a toxic gas)
test: take damp blue litmus paper and hold it where the gas it
result: chlorine turns damp blue litmus paper to white
result: chlorine turns damp blue litmus paper to white
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to test for the product carbon dioxide, the gas produced is bubbled through clear limewater and if carbon dioxide is present, the limewater will go cloudy.
why?
why?
limewater is calcium hydroxide. when carbon dioxide is passed through, the product formed is calcium carbonate. this is white, chalky precipitate
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how to carry out a flame test?
take a sample of the metal on a wire and put it in a flame, the flame will turn a specific color, showing what metal it is
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what are the colors formed in flame tests for lithium, sodium, potassium, calcium and copper?
lithium = red
sodium = yellow
potassium = lilac
calcium = orange-red
copper = blue-green
sodium = yellow
potassium = lilac
calcium = orange-red
copper = blue-green
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metal cation tests (part 1)
you can identify some positive ions by reacting unknown compounds with sodium hydroxide
add dilute sodium hydroxide and gently heat
NH4+ using NaOH solution and identifying the gas evolved
what gas would be evolved = ammonia gas
how would you test for th
add dilute sodium hydroxide and gently heat
NH4+ using NaOH solution and identifying the gas evolved
what gas would be evolved = ammonia gas
how would you test for th
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metal cation tests (part 2)
some metal ions form colored precipitates with NaOH:
copper(II) ions, a blue precipitate appears
iron(II) ions, a green precipitate produced
iron(III), a brown precipitate is formed
copper(II) ions, a blue precipitate appears
iron(II) ions, a green precipitate produced
iron(III), a brown precipitate is formed
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describe the test for anions: halide ions
- add dilute nitric acid
- add silver nitrate solution
- if a precipitate forms halide ions are present
chloride gives a white precipitate
bromide gives a cream precipitate
iodide gives a yellow precipitate
- add silver nitrate solution
- if a precipitate forms halide ions are present
chloride gives a white precipitate
bromide gives a cream precipitate
iodide gives a yellow precipitate
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describe the test for anions: sulfate ions
- add dilute HCl
- add barium chloride solution
- white percipitate forms = sulfate ions present
- add barium chloride solution
- white percipitate forms = sulfate ions present
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describe the test for anions: carbonate ions
- carbonates will react with dilute acids to create carbon dioxide
- this gas can be bubbled through limewater, if the limewater goes cloudy, the gas is CO2
- this gas can be bubbled through limewater, if the limewater goes cloudy, the gas is CO2
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what is the test for water?
- add water to anhydrous copper (II) sulfate
- goes from white to blue
- AND
- cobalt chloride paper goes from blue to pink
- goes from white to blue
- AND
- cobalt chloride paper goes from blue to pink
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how can we test if water is 100% pure?
test its melting or boiling point
melting point of pure water = 0 degrees
boiling point of pure water = 100 degrees
melting point of pure water = 0 degrees
boiling point of pure water = 100 degrees
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Other cards in this set
Card 2
Front
how does methyl orange distinguish between acidic and alkaline solutions?
Back
alkaline - yellow
acidic - red
acidic - red
Card 3
Front
how does litmus solution distinguish between acidic and alkaline solutions?
Back
Card 4
Front
how does litmus paper distinguish between acidic and alkaline solutions?
Back
Card 5
Front
what does the pH scale measure and how can it be measured?
Back
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