Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Science Year 2 > Chemical changes > Flashcards

Chemical changes Flashcards

Learning Outcomes: Interactions - Chemical Changes 1. a. Deduce the chemical formulae of common monatomic ions using the Periodic Table. b. State the chemical formulae of common polyatomic ions (i.e. hydroxide, nitrate, sulfate, carbonate). c. Deduce the formulae of ionic compounds from the charges on the ions present and vice versa. d. Deduce the formulae of simple covalent substances from the relative numbers of atoms present and vice versa. 2. Identify a change that leads to the formation of

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

Which of the name of this ion exists?
(A) Copper (I)
(B) Copper (II)
(C) Copper (III)
(D) Copper (IV)

A

(A) and (B)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Which name of this ion exists?
(A) Iron (I)
(B) Iron (II)
(C) Iron (III)
(D) Iron (IV)

A

(B) and (C)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the fixed charge of Zinc?

A

Zn2+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the fixed charge of silver?

A

Ag+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Which name of this ion exists?
(A)Lead (I)
(B) Lead (II)
(C) Lead (III)
(D) Lead (IV)

A

(B) and (D)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the four polyatomic ions you learnt?

A

Hydroxide, Nitrate, Carbonate, Sulfate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

State the chemical formula of the four polyatomic ion you learn.

A

OH(-), CO3(2-), NO3(-), SO4(2-) do remember to write in subscript

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the chemical formulate of nitride?

A

N3-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

For polyatomic ions containing oxygen atoms, names usually end in -ate.

True or False?

A

False. For polyatomic ions containing oxygen atoms, names usually end in -ate or -ite*, except for the case of hydroxide which ends in -ide.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is/are the bond(s) present in sodium hydroxide?

A

OH covalent bond
But since Oxygen need to gain two more electrons and hydrogen need to lose one electron, oxygen would therefore need one more valence electron from Na (Sodium)

Hence between Na and OH there is an ionic bond.

So a polyatomic ion has both covalent bond and ionic bond, but overall it is a ionic bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How do you test for carbon dioxide?

A

Bubble the gas through limewater and white precipitate is formed.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the chemical formula of sulfite given that sulfate is SO42-?

A

SO32-
-ate has one more oxygen than -ite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the law of conservation of mass?

A

Matter is neither created nor destroyed during a chemical reaction. While bonds are broken and formed, atoms are not gained nor lost in a chemical change.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the three methods to balance chemical equation?

A
  1. Balance substances with only 1 element last
  2. Apply “fraction trick”
  3. For acid reactions, balance metals first, and leave hydrogen and oxygen last.

Metals—-> Other elements—-> hydrogen and oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

A simple molecule has the chemical formula X2Y. Which groups are elements X and Y likely to belong to?
Element X. Element Y
A. 1. 16
B. 2. 17
C. 16. 17.
D. 17. 16

A

(D). Keyword: “A simple molecule” this suggest that it is covalent substances and not an ionic compound.

Therefore option A and B are out
Structural formula
X—Y—X
X forms 1 covalent bond —> Group 17
Y forms 2 covalent bond—> Group 16

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

A molecule of a substance containing X atoms of carbon and Y atoms of hydrogen, CxHy, was burnt completely in oxygen to produce carbon dioxide and water as the only products.

Which of the following statements is true?
A X molecules of carbon dioxide will be produced.
B. (X/2) molecules of carbon dioxide will be produced.
C. Y molecules of water will be produced.
D. 2Y molecules of water will be produced.

A

(answer is A) can check explanation in ChatGPT just copy and paste

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Are covalent bonds strong or weak?

A

Strong

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the difference between physical change and chemical change?

A

Physical change reversible, change of state, shape, no new substances are formed (from my notes)

Physical change-properties of products are the same as the reactants (from overmugged)

Chemical change, new substances formed which have different properties from the reactant, usually involve energy exchange with heat or with the environment. usually irreversible (from my notes)

Chemical change— properties of products are different from that of the reactants. (Overmugged).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Define Synthesis.

A

Synthesis reactions occur when two or more substances combine to form a more complex substance. (Only one)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Define Decomposition.

A

Decomposition is a process in which a substance breaks down into two or more simpler substances.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Define Oxidation of metals

A

Oxidation of metals occurs when metallic elements react with oxygen to form metal oxides. This reaction usually happens when reactive metals are exposed to atmospheric oxygen.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Define Combustion.

A

Combustion refers to the reaction of a substance with oxygen (O2) and heat is produced.

Burning

Combustion is also commonly known as burning. Many processes around us are examples of combustion , e.g. burning of fossil fuel. Cellular respiration is a example of combustion since

Oxygen+ Glucose—> Carbon dioxide + Water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the four advantages of pH paper over pH meter?

A

pH paper, easy-to-use and time efficient
pH paper can be used on small sample sizes ( 1 drop of solution is sufficient) while for the pH meter, the sample solution needs to cover the entire bulb of the probe.
pH paper is disposable, this reduces the chances of contamination. (E.g. if probe is not cleared properly)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How do you test for hydrogen?

A

Gas extinguished a lighted splint with a ‘pop’ sound. Gas is hydrogen.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

If the soil is too acidic, what can you add to neutralise the excess acids and raise the pH of the soil so that the plants will thrive?

A

Quicklime (calcium oxide)
Slaked lime (Calcium hydroxide)
Limestone (Calcium carbonate)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

For every pH, there is a ____ difference in H+ hydrogen ions concentration.

A

10 times.
It is 1/10 dilute

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Air pollution has made many fresh water lakes acidic. Which compound will not reduce the acidity if added to these acidic lakes?
(A) calcium carbonate
(B) calcium chloride
(C) calcium hydroxide
(D) calcium oxide

A

B.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What are some examples of strong acid and what are their formula?

A

Sulfuric acid (H2SO4), hydrochloric acid (HCl) and nitric acid (HNO3)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What are some examples of weak acid?

A

Ethanoic acid and citric acid
They are organic acids which are normally found in fruits and vegetables.

30
Q

What are the physical properties of acids?

A

Acids have a sour taste.
Acids turn blue litmus paper red.
Acids have pH values less than 7.
Acids are good conductors of electricity.

31
Q

What is the difference between a base and alkali?

A

Alkalis are bases that are soluble in water, but not all bases are soluble in water.

32
Q

What is an acid?

A

An acid is a substance that produces hydrogen ions (H+) when dissolved in water.

33
Q

When does an acid show their properties?

A

Acids only show their properties when they are dissolve in water. This is because acids dissociate in water to form hydrogen ions which are responsible for the acidic properties.

34
Q

What is a base?

A

A base is a substance that reacts with an acid to form a salt and water. It is any metal oxide or hydroxide. Alkalis dissociate to produce hydroxide ions (OH-) when dissolved in water.

35
Q

What are some examples of alkalis?

A

Calcium hydroxide
Group 1 ,metal oxides or hydroxides
Ammonia (weak alkali)

36
Q

Not all hydroxides are soluble in water, thus not all hydroxides are alkalis.
True or false?

A

True

37
Q

What are the physical properties of alkalis?

A

Alkalis have a bitter taste
Alkalis have a slippery and soapy feel.
Alkalis turn red litmus paper blue.
Alkalis have pH values more than 7.
Alkalis are good conductors of electricity.

38
Q

The labels on three reagent bottles containing dilute nitric acid, dilute citric acid and sodium carbonate solution have fallen off.

Explain how you can identify the three reagents using only test tubes and the solutions themselves.

A

Pour 2 cm cube of each substances into one test tube. Label them A, B and C.

Nitric acid + Sodium carbonate effervescence, of a colourless, odourless MORE vigorous effervescence

Nitric acid +citric acid no visible reaction

Citric acid + sodium carbonate effervescence of a colourless, odourless gas, LESS vigorous effervescence

Citric acid is a weak acid while nitric acid is a strong acid.

39
Q

What are the three reactions of acids?

A

AMSH Acids+reactive metals—> salt and hydrogen gas
ABSW. Acids+ Bases—> Salt and water (neutralisation)
CASWC Acids+ Carbonates—> salt, water and carbon dioxide.

40
Q

What are the three unreactive metals that do not react with dilute acids?

A

Copper, Silver and gold.

41
Q

Reaction of acids with bases is an e___thermic reaction.

A

The reaction gives out heat. It is an exothermic reaction.

Vs endothermic take in heat

42
Q

What is the pH range and the colour of universal indicator for strong acid?

A

The pH range is 1-3.
The colour of universal indicator is red.

43
Q

What is the pH range and the colour of universal indicator of weak acid?

A

The pH range is from 4-6
The colour of universal indicator is orange/yellow.

44
Q

What is the pH range and the colour of universal indicator of neutral type of solution?

A

The pH is 7.
The colour of universal indicator is green.

45
Q

What is the pH range of weak alkali and the colour of universal indicator?

A

The pH range of weak alkali is 8-11.
The colour of universal indicator is blue.

46
Q

What is the pH range of strong alkali and the colour of universal indicator?

A

The pH range is from 12-14.
The colour of universal indicator is violet.

47
Q

What do you need to take note for the pH of the solution?

A

The pH of the solution depends on both strength and concentration of solution. For example, a strong acid (e.g. hydrochloric acid) when diluted sufficiently with distilled water can show a pH of 6. similarly, a sufficiently concentrated weak acid (e.g. ethanoic acid) can show a pH of 3.

48
Q

How do you test for ammonia?

A

There is a pungent smell. The test-tube feels cold.

49
Q

How do you test for oxygen?

A

Glowing splint relights when place into the test tube.

50
Q

State whether carbon dioxide, hydrogen, oxygen and ammonia are acid, alkali or neutral.

A

Hydrogen and oxygen is neutral.
Carbon dioxide is an acid.
Ammonia is an alkali.

51
Q

What is the difference between explanation question and describe question for chemical change or physical change?

A

Explanation: need to explain the different characteristics of physical or chemical change.

Describe: (5 senses) colour change, effervescence.

52
Q

Hydrogen can only form positive ions. True or false?

A

False. Hydrogen can form both positive and negative ions.

53
Q

What is the ion name of H-?

A

Hydride

54
Q

What are cations?

A

Atoms of metals usually lose valence electrons to attain electronic configurations of noble gas, thereby forming positive ions known as cations.

55
Q

What are anions?

A

Atoms of non-metals usually gain valence electrons to attain electronic configurations, thereby forming negative ions known as anions.

56
Q

For monoatomic negative ion, its name usually ends in _____.

A

its name usually ends in -ide.

57
Q

What are the two things to take note of polyatomic ions?

A

For polyatomic ions, containing oxygen atoms, names usually end in -ate or -ite*, except for the case of hydroxide which ends in -ide.

Polyatomic ions are formed when two or more covalently-bonded atoms, acting as a collective unit, gain or lose electrons. For example, in an OH- ion, the O and H atoms are covalently bonded, and they gained a total of 1 electron.

58
Q

What is the chemical formula of dinitrogen pentoxide?

A

N2O5

59
Q

What are the prefixes for indicating numbers?
Mono

A

Mono (1)
Di (2)
Tri (3)
Tetra (4)
Penta (5)
Hexa (6)
Hepta (7)
Octa (8)
Nona (9)
Deca (10)

60
Q

What are the four reactions for potassium sulfate?

A

For this kind of question, you should list it out by word equation before converting it to chemical equation.

Potassium + Sulfuric acid (acid+ reactive metal—dangerous)

Potassium carbonate + Sulfuric acid—>…
(Acid +carbonate)

Potassium hydroxide +Sulfuric acid—> (neutralisation)

Potassium oxide +Sulfuric acid—> …
(Acid + metal oxide (base))

61
Q

If there is no colour change, is that a chemical or physical change?

A

The absence of a color change does not definitively indicate whether a change is physical or chemical. Both physical and chemical changes can occur without a noticeable color change. (ChatGPT)

62
Q

Which statement about bases are correct?
1 A base can be a metal hydroxide or non-metal oxide.
2 All alkalis are bases but not all bases are alkalis.
3 All bases turn red limes paper blue.
A 2 only
B 3 only
C 2 and 3 only
D 1,2 and 3 only

A

A
A base is a metal hydroxide or a metal oxide not a non-metal oxide. (Statement 1 is wrong)
Statement 2 is correct
Statement 3 is wrong, because in order for the red litmus paper to turn blue the base needs to be soluble or have water. Not all bases are soluble, only alkalis.

This is also why in order to test gas, we need to moisten the litmus paper first.

63
Q

Carbon dioxide is a metabolic waste product derived from cellular respiration. It is transported to the lungs by blood. Carbon dioxide can combine with water to form carbonic acid, H2CO3.

In blood, each carbonic acid molecule (H2CO3) dissociates to form one bicarbonate ion and one hydrogen ion.

(i) State the chemical formula of the bicarbonate ion.
(ii)By describing changes in the amount of ions, state and explain how carbon dioxide affects the pH of blood.

A

(i) HCO3(subscript)-
(ii) Concentration of H+ ions increase causing decrease in pH. CO2 dissolves in water to form carbonic acid, which dissociates to form and increases he concentration of H+ in blood, decreasing the pH.

64
Q

NaOH + HCL—> NaCL +H2O
What is this type of chemical reaction?

A

Neutralisation

65
Q

What is the definition of neutralisation?

A

neutralisation is the reaction between an acid and base to form salt and water only.

66
Q

When liquid HCL boils, its particles become more widely spaced.
Which property of the particles has the most influence on the energy required to boil liquid HCL?
A the forces of attraction between the ions
B the forces of attraction between the molecules
C the size of the ionic lattice
D the strength of the covalent bonds in the molecules

A

B

67
Q

Hydrogen can form both H+ and H- ions. Which statement is correct?
A H+ ions has no electrons in the first electron shell
B H+ ions has more protons than an H-ion.
C H- ion has one more electron than an H+ ion.
D H- ion is formed when a hydrogen atom loses an electron.

A

A

68
Q

Gas X has no effect on both moist red and blue litmus papers. When a lighted splint is inserted into a test-tube containing X, the lighted splint is extinguished.
What could gas X be?
A ammonia
B carbon dioxide
C oxygen
D nitrogen

A

D

69
Q

Propanoic acid, CH3CH2CO2H, is a weak acid. It ionises in water to give CH3CH2CO2- and H+ ions.
both propanoic acid and nitric cid are colour less.
(a) a student was given equal concentrations of propanoic acid and nitric acid for an experiment in the school laboratory. Suggest the pH values of propanoic acid and nitric acid.
pH of propanoic acid:_______
PH of nitric acid:_______

(b) Propanoic acid reacts with magnesium carbonate to form a salt, a gas and water.
(i) State the chemical formula of the salt formed.
(ii) Name the gas formed, and describe the confirmatory test for the gas.
Gas:_____
Confirmatory test:________

A

(a) pH of propanoic acid: 5
pH of nitric acid: 3 (strong acid usually pH 1-3)

(b) (i) Mg(CH3CH2CO2)2
(Remember that the H was dissolved to produce H+

(ii) gas: carbon dioxide
Confirmatory test: Bubble the gas through limewater and white precipitate is formed.

70
Q

The diagram shows crystals of sodium chloride (NaCL) being dissolved in water.
NaCL crystals + water—(dissolving)—> NaCL solution

The table below shows the conclusions and reasons made by four students.

Aaron chemical change(conclusion) A new product, NaCL solution, is formed.
Ben physical change (conclusion) The solution remains colourless (reason)
Cayden physical change(conclusion) no new substance is formed (reason)
Dylan chemical change (conclusion) dissolving is a chemical reaction (reason)

Whose conclusion and reason are both correct?
A Aaron and Dylan
B Ben and Cayden
C Aaron only
D Cayden only

A

D

71
Q

A soil sample from a garden has a pH of 6.0.
Which compound is most suitable to neutralise the acidic soil?
A aqueous ammonia
B calcium hydroxide
C hydrogen peroxide
D potassium nitrate

A

B

72
Q

Are acids ionic compounds or covalent substances?

A

Acids are usually covalent substances with the ability to dissociate in water to form ions. They are not ionic compounds.

Science Year 2 (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions