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Edexcel GCSE Chemistry (9-1) COPY RIRI > SC8 - Acids and Alkalis > Flashcards

SC8 - Acids and Alkalis Flashcards

1
Q

SC8a - What are alkalis a source of in solution?

A

OH- ions

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2
Q

SC8a - What are the tests for carbon dioxide?

A

bubble the gas through limewater (calcium hydroxide solution); the limewater turns milky if CO2 is present.

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3
Q

SC8a - What are the tests for hydrogen?

A
  1. Burning wooden splinter is extinguished in hydrogen 2. Hydrogen burns with a pale blue fame producing a pop sound Squeaky Pop Test!
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4
Q

SC8a - What colour is litmus in acidic solutions?

What colour is litmus in alkaline solution?

A

Red in acidic solutions

Blue when in alkaline solutions

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5
Q

SC8a - What colour is methyl orange in acidic solution?

What colour is methyl orange in alkaline solution?

A

Red in acid

Yellow in alkaline

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6
Q

SC8a - What colour is phenolphthalein in acidic solution?

What colour is phenolphthalein in alkaline solutions?

A

Colourless in acidic solutions

Pink in alkaline solution

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7
Q

SC8a -What are acids a source of in solution?

A

H+ ions

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8
Q

SC8b - How can you test the acidity of a solution?

A

Using universal indicator

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9
Q

SC8b - How do you calculate concentration?

A

Concentration = amount (g)/volume (dm3)

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10
Q

SC8b - How do you make a solution more concentrated?

A

Add more solute / Evaporate some water

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11
Q

SC8b - How do you make a solution more dilute?

A

Add more water

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12
Q

SC8b - What is a base?

A

A substance that reacts with an acid to make salt and water only

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13
Q

SC8b - What is the chemical formula for hydrochloric acid?

A

HCl

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14
Q

SC8b - What is the chemical formula for nitric acid?

A

HNO3

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15
Q

SC8b - What is the chemical formula for sulfuric acid?

A

H2SO4 (aq)

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16
Q

SC8b - Why do strong acids have a lower pH than weak acids?

A

Strong acids completely dissociate in H+ ions when in solution; whereas weak acids only partially dissociate into H+ ions. This means there is a higher concentration of H+ ions in the strong acids, therefore they have a lower pH

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17
Q

SC8b -If the pH increases by 1; what happens to the concentration of hydrogen ions?

A

Decreased by a factor of 10

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18
Q

SC8c - How can soluble salt be made from acid and alkalis?

A

In an neutralisation reaction between an acid and an alkali. The end point of this reaction is found using an indicator. The salt can obtained from the solution by evaporation

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19
Q

SC8c - How do you convert cm into dm?

A

divide by 1000

20
Q

SC8c - Represent a neutralisation reaction in an equation

A

H+ + OH- —> H20

21
Q

SC8c CP - Describe how to prepare a soluble salt from an acid and base

A
  1. Add excess base to ensure all acid reacts
  2. Warm in water bath
  3. Filter out the unreactive solid
  4. Evaporate the water in water bath so the salt can be concentrated
  5. Leave to cool and for remaining water to evaporate so crystallisation can take place
22
Q

SC8c CP - Why; when making copper sulfate; do we add the metal oxide in excess?

A

To ensure all the acid reacts

23
Q

SC8c- How can soluble salt be made from acids and metals?

A

In a reaction; an acid and a metal makes a salt and a hydrogen.

24
Q

SC8d - What are spectator ions?

A

Ions that do not change during the reaction

25
Q

SC8e - Describe titration experiment

A
  1. Use a pipette to transfer 25cm3 of alkali NAOH into a conical flask
  2. Add 5 drop of indicator eg methyl orange which is yellow in alkali or phenothplaein which is pink In alkali into conical flask
  3. Make sure there is a white tile under the conical flask so color change is apparent
  4. Now add a known amount of acid into the burette
  5. Open the tap of burette slowly and allow the drops of acid to go into the conical flask whilst swirling it and do this until the solution is neutralised so phenothphlain will turn coloruless in neutral
  6. After reaching the endpoint, record the volume of acid dispensed as indicated on the burette. Calculate the amount of acid used by subtracting the initial volume from the final volume observed.
  7. Repeat this experiment and find average to then find the conc of acid
26
Q

SC8e - How do we make a pure dry salt from titration?

A
  • Carry out a titration - Note the exact volume of acid needed to neutralise the alkali - Use the burette to add the correct volume of acid without the indicator this time (as alrdy know correct amount of acid to put in)- Evaporate water from solution formed, crystallisation
27
Q

SC8e - What is a buret?

A

A long; narrow; graduated tube used to add titrate

28
Q

SC8e - What is a stopcock?

A

A small tap that is used to control the flow of the titrate during titration

29
Q

SC8f - hat metals react steadily with dilute acids?

A

Metals in the middle of the reactivity series such as magnesium or zinc
(because metals in the top react violently and metals in the end might not even react)

30
Q

SC8f - State the general equation for the reaction between an acid and a metal carbonate

A

metal carbonate + acid –> salt + water + carbon dioxide

31
Q

SC8f - What is a reduction reaction?

A

gain of electrons

32
Q

SC8f - What is an oxidation reaction?

A

loss of electrons

33
Q

SC8f - What is effervescence?

A

rapid escape of a gas from a liquid

34
Q

SC8f - What metals do not react with dilute acids?

A

Copper; Silver

35
Q

SC8f - What metals react explosively with dilute acids?

A

Potassium; Sodium

36
Q

SC8g - Describe the steps required to produce a pure; dry sample of an insoluble salt from two soluble salts

A

-1. Mix the 2 soluble salts together in water solution form
2. The insoluble salt will form as a precipitate
3. Wash the precipitate in the beaker to remove the soluble impurities and pour this through a filter paper to filter out the water
4. Capture and remove the precipitate from filter paper and dry in warm oven

37
Q

SC8g - How can soluble salt be made from ammonia solution?

A

By reacting ammonia solution with an acid; ammonium salt and water are produced.

38
Q

SC8g - How can we check whether a precipitate will form?

A

To determine if a precipitate will form in a reaction, check the solubility of the potential products using solubility rules. If any of the reaction products is an insoluble salt, it will form a precipitate. If all possible products are soluble, they remain dissolved, and no precipitate will be seen

39
Q

SC8g - What are ammonium salts used for?

A

fertilisers

40
Q

SC8g - What carbonates are soluble?

A

sodium; potassium; ammonium

41
Q

SC8g - What chlorides are insoluble?

A

Silver and lead

42
Q

SC8g - What happens when two solutions containing soluble salts react together?

A

The metals from the salts swap

43
Q

SC8g - What hydroxides are soluble?

A

sodium; potassium; ammonium

44
Q

SC8g - What is a precipitation reaction?

A

When two soluble substances react together to make a product which is insoluble (the precipitate)

45
Q

SC8g - What substances are generally insoluble?

A

Most carbonates most hydroxides

46
Q

SC8g - What substances are generally soluble?

A

all common sodium,pottassium and ammonium salts all nitrates most chlorides most sulfates

47
Q

SC8g - What sulfates are insoluble?

A

Lead; barium and calcium

Edexcel GCSE Chemistry (9-1) COPY RIRI (24 decks)

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