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Chemistry > Triple Paper 1 > Flashcards

Triple Paper 1 Flashcards

1
Q

How do you calculate relative formula mass?

A

You first find or get given the relative atomic masses, then using the formula of the equation add it up.

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2
Q

How use moles to calculate the masses of reactants?

A

The table method. If cant remember https://www.youtube.com/watch?v=TV6n5MFH6IU and try the questions

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3
Q

What is an empirical formula?

A

The simplest whole number ratio of atoms of each element in a compound

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4
Q

How do you find the molecular formula of a compound from its empirical formula and its relative molecular mass?

A

Keep the formula the same but scale it up to meet the mr of the molecular formula

For example 
CH2 (empircal)
140 (relative molecular mass)
We know C=12 and H=2,
So its C10H20
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5
Q

Describe an experiment to determine the empirical formula of a simple compound such as magnesium oxide

A

Weigh a crucible (with its lid).
Put a sample of clean magnesium ribbon into the crucible and weigh it with the lid. Calculate the mass of magnesium by subtracting the mass of the empty crucible.
Strongly heat the crucible over a Bunsen burner for several minutes.
Carefully lift the lid from time to time to allow sufficient air into the crucible for the magnesium to fully oxidise without letting any magnesium oxide escape.
Continue heating until the mass of the crucible reaches a constant (maximum) mass, indicating that the reaction is complete
Measure the mass of the crucible and contents again. Calculate the mass of the magnesium oxide by subtracting the mass of the empty crucible.
To work out the empirical formula, you need the mass of the magnesium and the mass of the oxygen atoms as well. To find the mass of the oxygen atoms, subtract the mass of magnesium used from the mass of the magnesium oxide
Now divide each of the two masses by the relative atomic masses of the elements and simplify the ratio

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6
Q

What is the law of conservation of mass?

A

Matter cannot be created or destroyed. In other words, the mass of any one element at the beginning of a reaction will equal the mass of that element at the end of the reaction

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7
Q

Explain the law of conservation of mass applied to a closed system

A

No substances can enter or leave a closed system, so the mass of substances stay the same

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8
Q

How do you convert cm^3 to dm^3?

A

Divide by 1000

1 cm = 0.001 dm

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9
Q

How do you calculate concentration?

A

Concentration= mass/volume or concentration= moles /volume

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10
Q

What is avogadros constant

A

One mole of particles of a substance
6.02 × 10^23
Very Helpful video- https://www.youtube.com/watch?v=3y8YDlNeuRk

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11
Q

What is the equation for number of moles?

A

Number of moles=mass/mr

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12
Q

Explain why, in a reaction, the mass of product formed is
controlled by the mass of the reactant which is not in
excess

A

Because when the mass of reactant runs out no more product can be made as nothing can react to form the product

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13
Q

Why can compounds be classed as ionic

A

When a compound has a mixture of a metal and non-metal it is ionic

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14
Q

Why can compounds be classed as covalent

A

When a compound has a mixture of two or more non-metals it is covalent

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15
Q

What is the melting and boiling point of ionic compounds and why

A

In ionic compounds, there exists a strong force of attraction between the oppositely charged ions, so a large amount of energy is required to break the strong bonding force between the ions

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16
Q

Do ionic compounds conduct electricity?

A

Ionic compounds conduct electricity when molten (liquid) or in aqueous solution (dissolved in water) but not when solid

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17
Q

What is the melting and boiling point of covalent and why

A

Covalent compounds have a low melting and boiling point because they have weak intermoleculr forces

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18
Q

Do covalent compounds conduct electricity?

A

No, Covalent molecular structures do not conduct electricity because the molecules are neutral and there are no charged particles (no ions or electrons) to move and carry charge

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19
Q

What are graphite and diamond made of and what are they examples of?

A

Graphite and diamond are different forms of carbon and they are examples of covalent substances

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20
Q

Why is graphite used as a lubricant?

A

Graphite has weak covalent bonds that allow the layers of graphite to “slide” on top of one another with very little resistance making it a lubricant

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21
Q

Why is diamond used in cutting tools

A

The rigid network of carbon atoms, held together by strong covalent bonds, makes diamond very hard

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22
Q

Why is graphite used to make electrodes?

A

Because it has a high melting point and is a good conductor of electricity, which makes it a suitable material for the electrodes needed in electrolysis

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23
Q

What are polymers?

A

Polymers have very large molecules. The atoms in a polymer molecule are joined together by strong covalent bonds in long chains

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24
Q

What are some properties of metals

A 
high melting points
good conductors of electricity
good conductors of heat
high density
malleable
ductile
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25
Q

What are most metals

A

Most metals are shiny solids which have high melting

points, high density and are good conductors of electricity

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26
Q

What are most non-metals

A

They have have low boiling points and are poor

conductors of electricity

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27
Q

What ions do acid solutions contain?

A

Hydrogen ions (H+)

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28
Q

What ions do alkali solutions contain

A

hydroxide ions (OH-)

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29
Q

What pH do neutral solutions have?

A

pH of 7

30
Q

What pH’s are acids

A

Anything less that 7

31
Q

What pH’s are alkali solutions

A

Anything more than 7

32
Q

What effect do acids and alkalis have on Litmus paper?

A

Litmus paper is red below a pH of 4.5
It is blue above a pH of 8.3
If the paper turns purple, this indicates the pH is near neutral.

33
Q

What effects do acids and alkalis have on methyl orange?

A

When in an acid solution it is red and when in an alkaline solution it is yellow

34
Q

What effects do acids and alkalines solutions have on phenolphthalein

A

Phenolphthalein is colourless below pH 8.5 and attains a pink to deep red hue above pH 9.0.

35
Q

What does the pH of the solution depend on?

A

The higher the concentration of hydrogen ions in an acidic solution the lower the pH, and the higher the concentration of hydroxide ions in an alkaline solution the higher the pH

36
Q

If the hydrogen ion concentration of a solution increases by a factor of 10, then what will happen to the pH of the solution?

A

It will decrease by a pH of 1

37
Q

What does the term dilute mean?

A

There is less ions in the same volume than normal.

A solution containing a relatively small quantity of solute as compared with the amount of solvent

38
Q

What does the term concentrated mean?

A

There is more ions in the same volume than normal.

A concentrated solution is one that has a relatively large amount of dissolved solute

39
Q

What is a weak acid?

A

Weak acids are acids that don’t completely dissociate/ionise in solution

40
Q

What is a strong acid?

A

A strong acid is one that is completely dissociated or ionized in an aqueous solution

41
Q

What is a base?

A

A base is any substance that reacts with an acid to form a salt and water only

42
Q

Recall that alkalis are souble ____?

A

Bases

43
Q

What is the product of the reaction between an acid and a metal?

A

acid + metal → salt + hydrogen

44
Q

What is the product of the reaction between an acid and metal oxide?

A

acid + metal oxide → salt + water

45
Q

What is the product of the reaction between an acid and metal hydroxide

A

acid + metal hydroxide → salt + water

46
Q

What is the product of the reaction between an acid and a metal carbonate

A

acid + metal carbonate → salt + water + carbon dioxide

47
Q

What is the test for hydrogen?

A

The hydrogen test is putting a lit splint in a test tube of the suspected Hydrogen gas tube and if the splint is extinguished with a squeaky pop sound it is hydrogen.

48
Q

What is the test for carbon dioxide

A

The test for carbon dioxide is bubbling the gas through limewater and if it goes cloudy/milky then it is carbon dioxide

49
Q

What is a neutralisation reaction?

A

A reaction between an acid and a base that results in a neutral solution. (hydrogen ions (H+) from the acid react with hydroxide ions
(OH–) from the alkali to form water)

50
Q

What are electrolytes?

A

Electrolytes are ionic compounds in the molten state

or dissolved in water

51
Q

Cations migrate to which electrode?

A

The negatively charged cathode

52
Q

Anions migrate to which electrode

A

They migrate to the positively charged anode

53
Q

How do we know what forms at the anode?

A

Oxygen is produced, unless halide ions (chloride, bromide or iodide ions) are present. In that case,
chlorine, bromine or iodine are formed

54
Q

How do we know what is formed at the cathode?

A

Hydrogen is produced at the cathode if the metal is more reactive than hydrogen if the metal is less reactive than hydrogen (copper, silver or gold) then that will be formed

55
Q

What does oxidation mean?

A

Oxidation is the loss of electrons/oxygen thus the element will become positively charged or neutral
(oilrig)

56
Q

What does reduction mean?

A

Reduction is the gain of electrons/oxygen thus the element will become negatively charged or neutral
(oilrig)

57
Q

What electrode does reduction occur?

What electtode does reduction occur?

A

Reduction-Cathode

Oxidation-Anode

58
Q

How can electrolysis be used to purify copper?

A

The impure anode will gain electrons and the Cu2+ will become Cu and go to the cathode leaving pure copper and the impurity will be at the bottom of the anode

59
Q

Why are displacement reactions redox reactions?

A

Because the compounds which have (as one thing has been replaced) one has gained and one has lost electrons

60
Q

Where are most metal ores found?

A

In the earth’s crust

61
Q

What does the extraction of metals involve?

A

The reduction of ores

62
Q

Why does the metals place on the reactivity series effect the method used to extract metals?

A

Because the less reactive metals can be displaced by heating with carbon however most metals are much more reactive so need to use electrolysis

63
Q

What is bioleaching?

A

Certain bacteria can break down ores to produce an acidic solution containing copper(II) ions. The solution is called a leachate and the process is called bioleaching. Bioleaching does not need high temperatures, but it produces toxic substances, including sulfuric acid, which damage the environment.

64
Q

What is phytoectraction?

A

Plants are grown on an ore that contains lower amounts of metal, the plants absorb metal ions through their roots and concentrate these ions in their cells, the plants are harvested and burnt
and the ash left behind contains a higher concentration of the metal than the original ore
the ash is processed to obtain the metal

65
Q

What are the forth main stages of the life cycle assessment?

A
  1. obtaining the raw materials needed
  2. manufacturing the product
  3. using the product
  4. disposing of the product at the end of its useful life
    (https: //www.youtube.com/watch?v=Znnhe4BJH14)
66
Q

How do you calculate the percentage yield?

A

Percentage yield=(actual / theoretical)x100

67
Q

Why is the actual yield usually less than the theoretical yield?

A 
incomplete reactions
practical losses 
side reactions (unwanted reactions that compete with the desired reaction)
reversible reactions
impurities in reactants
68
Q

How do you calculate the atom economy?

A

atom economy=

(mr of the desired product / mr of all reactants)× 100

69
Q

How do you calculate the volume of a known amount of gas

A

Volume = amount in mol × molar volume

The 24dm one

70
Q

How do we investigate the change in pH on adding

powdered calcium hydroxide or calcium oxide to a fixed volume of dilute hydrochloric acid?

A

1) Use a measuring cylinder to add dilute hydrochloric acid to a beaker.
2) Dip a clean glass rod into the contents of the beaker.
3) Use it to transfer a drop of liquid to a piece of universal indicator paper on a white tile.
4) Wait 30 seconds, then match the colour to a pH colour chart.
5) Record the estimated pH.
6) Add a level spatula of calcium hydroxide powder to the beaker.
7) Stir thoroughly, then estimate and record the pH of the mixture (as in step 2).
8) Repeat steps 3 and 4 until there are no more changes in pH.
9) Record your results

https://www.bbc.co.uk/bitesize/guides/z8jt4qt/revision/4

71
Q

How do you investigate the electrolysis of copper sulfate

solution with inert electrodes and copper electrodes

A

1) Pour some copper sulfate solution into a beaker.
2) Place two graphite rods into the copper sulfate solution.
3) Attach one electrode to the negative terminal of a dc supply, and the other electrode to the positive terminal.
4) Completely fill two small test tubes with copper sulfate solution and position a test tube over each electrode as shown in the diagram.
5) Turn on the power supply and observe what happens at each electrode.
6) Test any gas produced with a glowing splint and a burning splint.
7) Record your observations and the results of your tests.

72
Q

How do you carry out an accurate acid-alkali titration, using burette, pipette and a suitable indicator?

A

1) Use the pipette and pipette filler to add 25 cm3 of alkali to a clean conical flask.
2) Add a few drops of indicator and put the conical flask on a white tile.
3) Fill the burette with acid and note the starting volume.
4) Slowly add the acid from the burette to the alkali in the conical flask, swirling to mix.
5) Stop adding the acid when the end-point is reached (the appropriate colour change in the indicator happens). Note the final volume reading.
Repeat steps 1 to 5 until you get concordant readings

Chemistry (2 decks)

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