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term 3 sci > chem Apr 18 (🎉🎂💀) > Flashcards

chem Apr 18 (🎉🎂💀) Flashcards

1
Q

What is a chemical reaction?

A

A change in which atoms are rearranged to create new substances

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2
Q

what happens in a chemical reaction?

A

atoms are rearranged

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3
Q

All chemical reactions

A

Make new substances

Transfer energy to or from surroundings.
Are not easily reversible
Have reactants and products that have the same mass

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4
Q

indicators that a chemical reaction is happening

A

Visible flames/sparks
Change in smell
Change in colour
Change in temperature
Loud bang/effervescence

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5
Q

Uses of chemical reactions

A

Creation of medicines
Production of fabrics
Cement
Combustion of fossil fuels for power

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6
Q

Useless chemical reactions

A

rusting (oxidation)
food rotting

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7
Q

In a physical change…

A

Change of state and dissolving are reversible

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8
Q

what is a fuel?

A

a material that burns to transfer energy by heating

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9
Q

examples of fuels

A

wood, coal, biogas, LPG, petrol, diesel

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10
Q

what are fossil fuels

A

fuels that are made from the remains of animals and plants that died millions of years ago,

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11
Q

examples of fossil fuels

A

coal, oil and natural gas

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12
Q

what are oxidation reactions?

A

In oxidation reactions substances join with oxygen to form oxides

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13
Q

examples of oxidation reactions

A

rusting and combustion

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14
Q

what is combustion

A

A chemical reaction in which a substance reacts quickly with oxygen and gives out light and heat.

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15
Q

examples of combustion reaction

A

Methane+Oxygen–> Carbon dioxide + water
glucose+oxygen–> Carbon dioxide+water
Magnesium+ Oxygen–> Magnesium oxide

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16
Q

what is decomposition?

A

A chemical reaction in which a compound breaks down to form simpler compounds and/or elements (usually with heat (thermal decomposition)).

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17
Q

Difference between decomposition and combustion

A

A decomposition reaction produces multiple products from a single reactant. On the other hand a combustion reaction is a reaction between a substance and oxygen to make oxides.

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18
Q

examples of decomposition reactions

A

Hydrogen peroxide (H2O2)–> water+oxygen
Copper carbonate–> Copper oxide+Carbon dioxide

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19
Q

what is the law of conservation of mass

A

law that states that the mass of the reactants MUST be the same as that of the products.

In a chemical reaction, mass is neither created nor destroyed.

20
Q

example of law of conservation of mass in action

A

Copper oxide + carbon dioxide–> Copper Carbonate
(87g) (50g) (137g)

21
Q

Endothermic change

A

energy from the surroundings ENters the system (chemical reaction)

22
Q

Exothermic change

A

energy from the chemical reaction EXits and is transferred to the surroundings

23
Q

examples of endothermic processes

A

melting ice cubes- takes in energy from surroundings to melt

melting, boiling, and evaporation- takes in energy to melt, boiling takes in energy so that water becomes gas same for evap

sweating- liquid from skin evaporates :))

24
Q

example of exothermic processes

A

combustion- energy exits the reaction

freezing water- requires the release of energy for liquid to become solid

rusting- generates lots of heat

respiration

25
Q

On which side of a word equation do the reactants go?

A

On the left

26
Q

What arethe products formedwhen a carbon based fuel undergoes combustion?

A

CO2 + H2O (Carbon dioxide and water)

27
Q

What does thermal decompositionmean?

A

The breaking down of substances by using heat

28
Q

What is produced when magnesium carbonate undergoes thermal decomposition?

A

Magnesium oxide and carbon dioxide
(no water cuz no hydrogen 😒)

29
Q

Why in a chemical reaction can it sometimes appear that the massis not being conserved?

A

A gascould be produced which means that the mass it accounts for will escape

30
Q

What is a physical change?

A

One where the physical properties of a substance changes, buta new substance is not formed. Particles may move or be arranged differently

31
Q

What is meant by a reversible reaction?

A

A reaction in which the you can get back to the substances you started with (physical)

32
Q

examples of physical change

A

Melting an ice cube.
Boiling water.
Mixing sand and water.
Breaking a glass.
Dissolving sugar and water.

33
Q

physical changes can/cannot be exothermic/endothermic

A

can

34
Q

examples of chemical change

A

combustion
respiration
photosynthesis

35
Q

Is ice melting a physical or achemical change?

A

Physical

36
Q

In which type of reaction will energy be transferred to the surroundings?

A

Exothermic

37
Q

In which type of reactions will energy escape the surroundings and enter the system

A

Endothermic

38
Q

What will happen to the temperature in anendothermic reaction?

A

It decreases

39
Q

the temperature of the surroundings/system is measured

A

SURROUNDINGS🤬

40
Q

What will happen to the temperature in anexothermic reaction?

A

it increases

41
Q

Why is an instant ice pack an example of an endothermic reaction?

A

As it takes in energy from the surroundings and decreases the temperature of the surroundings

42
Q

Doesmaking bonds require or release energy?

A

RELEASES to minimize the repulsion between the atoms.

43
Q

Ifmore energy is needed for breaking bonds that is released from making bonds, which type of reaction will this be?

A

ENDOTHERMIC

44
Q

Ifless energy is needed for breaking bonds than is released from making bonds, which type of reaction will this be?

A

EXOTHERMIC

45
Q

What is a catalyst?

A

A chemical which speeds up the reaction and lowers the energy needed for a reaction

term 3 sci (3 decks)

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