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Chem <3 > deck_16581781 > Flashcards

deck_16581781 Flashcards

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1
Q

Suggest why the stopper must be put in the conical flask as quickly as possible in
step 3.

A

to reduce the escape of gas

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2
Q

Which two changes would increase the mean time taken to collect 20 cm3 of gas?

Use a catalyst
Use a larger conical flask
Use a lower temperature
Use smaller pieces of zinc
Use sulfuric acid of a lower concentration

A

use a lower temperature

use sulfuric acid of a lower
concentration

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3
Q

Describe the test for hydrogen gas.
Give the result of the test.

A

lit splint

burns with a (squeaky) pop
sound

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4
Q

Limewater is an aqueous solution of _______

A

calcium hydroxide

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5
Q

Give the result of the test when carbon dioxide is bubbled through limewater

A

(limewater turns) milky / cloudy a

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6
Q

What is reacted with ethanol to produce ethanoic acid?

A

an oxidising agent

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7
Q

whats ethanols product of reaction with ethanoic acid?

A

Ethyl ethanoate

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8
Q

whats sodium carbonates product of reaction with ethanoic acid?

A

carbon dioxide

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9
Q

(6 MARKS)
Plan a method the scientist could use to show that the sample of medicine contains
potassium ions and bromide ions.
The scientist has:
* a Bunsen burner
* a metal wire
* test tubes
* a dropping pipette
* distilled water
* dilute nitric acid
* silver nitrate solution.

A

(potassium ions)
* place sample on (clean metal) wire
* introduce into (blue / non-luminous) flame
* using (Bunsen) burner
* observe lilac flame colour
* which shows presence of potassium (ions)
(bromide ions)
* dissolve sample
* in (distilled) water
* in test tube
* add (dilute) nitric acid
* add silver nitrate (solution)
* using (dropping) pipette
* observe cream precipitate (formed after addition of silver
nitrate solution)
* which shows presence of bromide (ions)

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10
Q

Which instrumental method could be used to show the presence of potassium ions ?

A

flame emission spectroscopy

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11
Q

3 Give one advantage of flame emission spectroscopy method instead of a chemical test.

A
  • (more) accurate
  • (more) sensitive
  • fast(er)
  • determine the concentration
    of ions present
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12
Q

Carbon dioxide and methane are greenhouse gases.
0 4 . 1 Which of the following is also a greenhouse gas?

A

Water vapour

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13
Q

Explain why the increase in world population may have caused the increase in the
concentration of carbon dioxide in the atmosphere.

A

(increased population so) more
energy required
(so) more (fossil) fuels burned
OR
(increased population so) more
farmland required (1)
(so) more deforestation (1)

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14
Q

Explain why the increase in world population may have caused the increase in the
concentration of methane in the atmosphere.

A

(increased population so) more
food required
(so) more methane-producing
food production
OR
(increased population so) more
waste produced (1)
(which) produces more methane
on decomposition (1)

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15
Q

Describe two potential effects of the increase in the mean temperature of the
atmosphere at the Earth’s surface.

A
  • melting ice
  • rising sea levels
  • flooding
  • extremes of weather
  • loss of habitats
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16
Q

The mean temperature of the atmosphere at the Earth’s surface has increased.
Most scientists think that this has been caused by an increase in the concentration of
greenhouse gases in the atmosphere.
Give one reason why some scientists do not accept this theory.

A

there may be other reasons for
changes in the (mean)
temperature (of the atmosphere
at the Earth’s surface)

allow difficult to model

17
Q

Describe a test to show the presence of copper(II) ions in a solution of
copper(II) sulfate.
Give the result of the test.

A

(test) (add) sodium hydroxide
(solution)
(result) blue precipitate
OR
(test) flame test (1)
(result) green (flame) (1)

18
Q

Describe what is meant by bioleaching.

A

the use of) bacteria
to produce leachate solutions
(that contain metal / copper
compounds)

19
Q

Describe what is meant by bioleaching.

A

the use of) bacteria
to produce leachate solutions
(that contain metal / copper
compounds)

20
Q

Explain why the Rf values for the red dye are different using the two types of
chromatography paper.

A

the Rf value is smaller for Paper
A
(because the red dye) is more
attracted to Paper A (than to
Paper B)
(so the red dye) spends a
greater (proportion of the) time
distributed in Paper A (than in
Paper B)

21
Q

What other change to the investigation could result in a different Rf value for the
red dye?

A

use a different solvent

22
Q

A student investigated the rate of this reaction.
This is the method used.]
1. Add 50 cm3 of 2.0 mol/dm3 hydrogen peroxide solution to a conical flask.
2. Add 1.0 g of manganese dioxide to the conical flask.
3. Place the conical flask on a balance and start a timer.
4. Record the total mass lost from the conical flask every 20 seconds for 180 seconds.

Explain why the mass of the conical flask and contents decreased.

A

(oxygen is) a gas

(which) escaped from the flask

23
Q

Poly(ethene) can be strengthened with wood particles to make a building material.
The building material consists of a wood particle reinforcement embedded in a
poly(ethene) matrix.

What general name is given to materials like this?

A

composites

24
Q

Name the small molecule produced when beta-alanine polymerises.

A

water

25
Q

Give the general name for the four different monomers which make up the structure

A

nucleotides

26
Q

15.0 g of anhydrous copper sulfate completely changes into hydrated copper sulfate
when water is added.
Calculate the amount of energy transferred to the surroundings

A

15.0
2.99 × 1.47
= 7.37 (kJ)

27
Q

The reaction mixture is green when both copper compounds are present in a solution
at equilibrium.
How can the equilibrium position be shifted to make the reaction mixture more yellow?

A

add more hydrochloric acid

28
Q

How is potassium chloride (compound A) obtained from the Earth?

A

mining

29
Q

Name one other compound that could be used instead of potassium chloride
(compound A) to give a similar improvement in agricultural productivity

A

potassium sulfate

30
Q

Nitric acid is needed to produce ammonium nitrate (compound B).
Name a compound needed to produce nitric acid.

A

ammonia

31
Q

Phosphate rock contains phosphorus compounds.
Plants absorb phosphorus from compounds dissolved in rainwater.
Suggest why phosphate rock cannot be used directly as a fertiliser.

A

(phosphate rock is) insoluble (in
water)

32
Q

Name the salts which are produced by treating phosphate rock with:
* sulfuric acid
* phosphoric acid.

A

Name the salts which are produced by treating phosphate rock with:
* sulfuric acid
* phosphoric acid.

Chem <3 (7 decks)

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