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CHEMISTRY > Acids and Salt preparation Methods (TOPIC 18) > Flashcards

Acids and Salt preparation Methods (TOPIC 18) Flashcards

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1
Q

Why is a PH probe better than an indicator?

A

More accurate and precise

Does not involve adding anything to substances that may affect results

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2
Q

What are acids?

A

Forms an aqeous solution with a PH of less than 7

Proton donor

Produce H+ ions when added to water

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3
Q

What are Bases?

A

Any substance with a PH greater than 7

Proton acceptor

Produces OH- ions when dissolved in water

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4
Q

What are alkalis?

A

Soluble bases

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5
Q

What is a neutralisation reaction?

A

Reaction between acid and alkai

Protons donated from acid and accepted by base

Produce salt and water

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6
Q

Litmus paper colour

ACID and ALKALINE

A

RED - Acidic

PURPLE - Neutral

BLUE - Alkaline

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7
Q

Phenolphthalein colour

ACID and ALKALINE

A

COLOURLESS - Acidic

PINK - Alkaline

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8
Q

Methyl Orange colour

ACID and ALKALINE

A

Red - Acidic

Yellow - alkaline

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9
Q

Acid + Metal Hydroxide → ?

Acid + Metal oxide → ?

A

Salt + Water

Salt + Water

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10
Q

Acid + Metal Carbonate →?

A

Salt + Water + CO2

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11
Q

Acid + Ammonia →?

A

Ammonium Salt

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12
Q

Method for making an insoluble salt?

A

Pick two soluble salts eg. lead nitrate and magnesium sulfate to make lead sulfate

In a test tube add 1 spatula of lead nitrate and use deionised water to dissolve it and make sure there are no ions.

Shake it to ensure the lead nitrate has dissolved.

Follow the same process with magnesium sulfate.

Tip the 2 solutions into one beaker and stir.

Filter into a conical flask. Rinse the content of the filter paper to ensure all soluble magnesium nitrate has been washed away.

Leave contents of filter paper (lead sulfate) to dry in a warm place.

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13
Q

What substances can act as bases?

A

Metal oxides

Metal Hydroxides

Ammonia

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14
Q

Titration Practical for finding unknown concentrations?

A
  1. Rinse the glass pipette with unknown concentration
  2. Using a glass pipette add 25cm^3 of the unknown concentration solution to a conical flask
  3. Rinse the burette with the known concentration
  4. Fill the burette with the known concentration
  5. Add 2-3 drops of chosen indicator - phenolphthalein
  6. Place the flask on a white tile and add solution drop by drop in the conical flask from the burette whilst swirling.
  7. Record the volume of acid used to neutralise the the alkali. Repeat the process until you get concordant results
  8. Use the formula Conc = Moles / Volume
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15
Q

Prepare soluble salt using an acid and an insoluble base

A

Use copper oxide and sulfuric acid to make copper sulfate.

Heat the acid in a water bath to speed up the rate of reaction

Then add the base- copper oxide - in excess to ensure all of the acid reacts
Keep adding until the copper sulfate is no longer clear blue stop adding the copper oxide when it does not react (stays black). Mix.

Filter off excess base so you are left with only soluble salt + water

Heat the solution in an evaporating basin gently using a bunsen burner and hot water bath until half the solution remains. Dipping glass rod in and seeing if crystals form.

Leave solution for 24 hours to allow crystal formation. Filter off solid salt and leave to dry.

Crystals are copper sulfate

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16
Q

Make a pure dry salt from an acid an alkali

A

Measure out a set amount of acid into a conical flask using a glass pipette. Add a few drops of phenolphthalein indicator.

Slowly add alkali to the acid using a burette until you reach the point of neutralisation where there is permanent colour change.

Then repeat the same experiment with the exactly the same amount of acid and alkali except without the indicator so the reaction is not contaminated.

The solution that is in the conical flask is salt and water. Slowly evaporate off half the water and then leave to crystalise. Filter off the solid and dry it - left with pure dry salt.

17
Q

What is a solvent?

A

The liquid in which the solute dissolves to form a solution

18
Q

What is a solution?

A

The mixture formed when a solute dissolves in a solvent

19
Q

What is a solute?

A

The substance that dissolves in a solvent to form a solution

20
Q

In chromatography why do the dyes travel up the paper at different rates?

A

Due to different sized particles and different attractions to the paper

21
Q

What is the Rf value?

A

The ratio between the distance travelled by the solute and the distance travelled by the solvent

22
Q

Rf value formula ?

A

Distance from baseline to the middle of the spot / Distance from the baseline to the solvent front

ALWAYS LESS THAN ONE

CHEMISTRY (19 decks)

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