Test your knowledge with the 10 questions next on transformations of matter. Clear your doubts about the topic with the comments after the feedback.
As for the types of transformations that matter undergoes, it is possible to state that
a) Changes occur only at the macroscopic level.
b) The changes are irreversible in the chemical composition and physical state of the material.
c) A physical transformation changes the appearance of the material but maintains its identity. A chemical transformation is evidenced by the formation of new substances.
d) We can distinguish a chemical change from a physical change by analyzing the reversibility of the change in physical state.
A physical transformation changes the material's appearance, but its composition remains the same. When a chemical change occurs, the identity of the material changes, as new substances are formed.
Physical phenomena are characterized by not altering the nature of matter. Thus,
a) there are no changes in physical properties, only in chemical properties.
b) only the general properties are modified.
c) the shape, size, appearance and physical state may change, but the composition cannot.
d) new substances can be formed, because the rearrangement of atoms in the material is a physical transformation.
In a physical phenomenon the substance retains its identity, so changes can occur in shape, size, appearance and physical state.
a) WRONG. As there is no change in the composition of matter in a physical transformation, its chemical properties remain the same.
b) WRONG. General properties, such as mass, volume, and inertia, apply to any material, regardless of its constitution.
d) WRONG. The formation of new substances characterizes a chemical transformation.
Observe the following situations and choose the correct alternative.
I. Crushing coffee beans
II. Transform copper bar into wires
III. Burn a sheet of paper
IV. explosion of fireworks
v. Banana peel rot
In which situations does the formation of new substances occur, which evidence the occurrence of chemical phenomena?
a) I, II and III
b) III, IV and V
c) I, III and V
d) I, II and IV
I. WRONG. Crushing just makes a change in the size of the coffee.
II. WRONG. Making wires from a bar changes only the shape of the copper.
III. CORRECT. The chemical transformation is evidenced by the emergence of coal and the release of smoke.
IV. CORRECT. The chemical transformation is evidenced by the color change.
v. CORRECT. The formation of pigments in the banana peel is the result of a decomposition reaction, which is evidenced by the change in color.
Please note that after burning the paper, lighting fireworks and browning the banana peel, there is no way for the materials to return to their original condition.
Observe the two situations and mark the correct alternative.
1. When heating an iron artifact, the material acquires a reddish color. Upon cooling, the metal returns to its usual color.
2. When an iron artifact is exposed to air and water for a long time, the material takes on an orange-red color.
a) In both situations the iron underwent a physical transformation.
b) In both situations the iron underwent a chemical transformation.
c) There was no transformation in the iron, only a change in color.
d) When heating and cooling the iron there was a physical transformation and exposure to air and water triggered a chemical transformation.
Heating and cooling iron does not change its composition, so it is a physical transformation.
Iron oxidation when exposed to humid environments is a natural process known as rust. Thus, a chemical transformation occurred, as a substance was formed and gradually deteriorates the original material.
Analyze the situations (column 1) and relate to the change in physical state that occurred (column 2).
I. boil water
II. hail formation
III. Melting ice cubes
IV. Disappearance of naphthalene
v. emergence of dew
The correct sequence is:
a) I.a, II.d, III.b, IV.e, V.c
b) I.c, II.a, III.e, IV.b, V.d
c) I.d, II.e, III.a, IV.b, V.c
d) I.e, II.b, III.c, IV.a, V.d
Correct alternative: b) I.c, II.a, III.e, IV.b, V.d
Boiling water: vaporization, which corresponds to the change from liquid to gaseous state.
Hail formation: solidification, which corresponds to the change from liquid to solid state.
Melting of ice cubes: melting, which corresponds to the change from solid to liquid state.
Disappearance of naphthalene: sublimation, which corresponds to the change from solid to gaseous state.
Appearance of dew: condensation, which corresponds to the change from gaseous to liquid state.
Classify the following phenomena into chemical and physical.
I. Dissolving sugar in water
II. Dissolving effervescent tablet in water
III. sugar caramelization
IV. Vinegar and bicarbonate mixture
v. Crumple an aluminum can
SAW. acetone evaporation
a) I, II and III are chemical phenomena, while IV, V and VI are physical phenomena
b) IV, V and VI are chemical phenomena, while I, II and III are physical phenomena
c) II, IV and V are chemical phenomena, while I, III and VI are physical phenomena
d) II, III and IV are chemical phenomena, while I, V and VI are physical phenomena
Dissolving sugar in water, crushing an aluminum can and evaporating acetone do not change the composition of materials, so they are physical phenomena.
The dissolution of an effervescent tablet and the mixture of vinegar and bicarbonate releases gases, which shows chemical transformations.
Caramelization is a chemical transformation of sugars upon reaching a certain temperature, where the formation of complex products occurs.
(ULBRA/2011) The International Year of Chemistry was an initiative of UNESCO (Organization of for Education, Science and Culture) and IUPAC (International Union of Pure Chemistry and Applied). With the slogan "Chemistry: our life, our future", the commemoration was approved at the 63rd General Assembly of the United Nations (UN), with the purpose of celebrating the great achievements of Chemistry and its enormous contribution to the well-being of humanity. The idea is a global commemoration that brings children, youth and adults together through educational activities and the dissemination of Chemistry.
(Química Nova vol.34 no.1 São Paulo 2011)
Which of the following processes does NOT involve a chemical reaction?
a) Formation of rust on a nail.
b) Combustion of wood in a fire.
c) Evaporation of sea water.
d) Rotting of a fruit.
e) Electrolysis of water.
The formation of rust on the nail, the combustion of wood, the rotting of a fruit and the electrolysis of water cause the emergence of new substances, therefore, they are chemical transformations.
Evaporation is a physical phenomenon, which consists of the change from liquid to gaseous state.
(FAG/2014) Tick the correct alternative.
a) Liquefaction is the name given to the change from solid to liquid.
b) Sublimation occurs when raindrops touch hot asphalt.
c) A physical phenomenon occurs when hydrogen peroxide (H2O2), contained in hydrogen peroxide, undergoes decomposition (Photolysis).
d) The system, consisting of two ice cubes in a glass of water, is three-phase.
e) Chemical reactions occur in the process of digestion of food.
a) WRONG. Liquefaction corresponds to the change from a gaseous to a liquid state.
b) WRONG. Sublimation is the transition from a solid to a gaseous state. When raindrops touch hot asphalt, evaporation occurs.
c) WRONG. A chemical phenomenon occurs, as there is the formation of water and oxygen in the decomposition reaction.
d) WRONG. Water in solid and liquid states constitutes a two-phase system.
e) CORRECT. In order to be absorbed by the body, food undergoes chemical reactions in the process of digestion.
(UCPEL/2011) At ambient pressure, iodine has a melting and boiling point above 100 °C. A student placed solid iodine in a clean bottle, which was hermetically sealed. The flask was left to stand at room temperature. After some time, the formation of iodine crystals was noticed on the cap of the flask due to the
a) sublimation of iodine.
b) boiling of iodine.
c) iodine melting
d) decomposition of iodine.
e) high chemical reactivity of iodine.
As with dry ice and mothballs, sublimation is a slow process that occurs naturally with iodine by absorbing heat and is characterized as the change from the solid to the gaseous state without passing through the liquid.
However, in contact with the cap, the material returned to a solid state.
(Enem/2017) Bauxite, composed of about 50% Al2O3, is the most important aluminum ore. The following steps are necessary to obtain metallic aluminum:
1. The dissolution of Al2O3 (s) is carried out in NaOH (aq) solution at 175 ºC, leading to the formation of the soluble species NaAI(OH)4 (aq).
2. With the cooling of the soluble part, precipitation of Al(OH)3(s) occurs.
3. When Al(OH)3(s) is heated to 1050°C, it decomposes into Al2O3(s) and H2O.
4. Al2O3(s) is transferred to an electrolytic vat and melted at high temperature with the aid of a flux.
5. By passing an electric current between the electrodes of the electrolytic cell, reduced aluminum is obtained at the cathode.
Steps 1, 3 and 5 refer, respectively, to phenomena:
a) Chemical, physical and physical.
b) Physical, physical and chemical.
c) Physical, chemical and physical.
d) Chemical, physical and chemical.
e) Chemical, chemical and chemical.
A chemical phenomenon is evidenced by the change in the chemical composition of matter, as new substances are generated.
1. Chemical phenomenon: the formation of the substance NaAI(OH)4 occurs.
3. Chemical phenomenon: the formation of substances Al2O3 and H2O occurs.
5. Chemical phenomenon: the formation of solid metallic aluminum substance occurs.
Gain more knowledge with the contents:
- Transformations of matter
- chemical transformations
- Physical and chemical phenomena
- properties of matter