AvaliaÇÃo 3º "C" - Quimica (Avaliação Final)

1. Na década de 70, alguns cientistas descobriram quais eram realmente as causas da destruição da camada de ozônio. Esse fenômeno, em termos químicos, pode ser descrito por meio das seguintes equações químicas: I- CF₂Cl_2(g) → CF₂Cl_(g) + Cl_(g)
II- Cl_(g) + O_3(g) → ClO_(g) + O_2(g)
III- ClO_(g) + O_(g)→ Cl_(g) + O_2(g) Considerando essas equações químicas, qual é a substância resultante da atividade humana que provoca esse fenômeno?

Cl.

O3.

CF2Cl2.

O.

The correct answer is CF2Cl2. The given chemical equations show that CF2Cl2 is broken down into CF2Cl and Cl, which then reacts with O3 to form ClO and O2. This reaction cycle leads to the destruction of ozone. CF2Cl2 is a substance known as chlorofluorocarbon (CFC), which was widely used in aerosol propellants, refrigerants, and solvents. The release of CFCs into the atmosphere by human activities is the main cause of ozone depletion.

Explanation

The correct answer is CF2Cl2. The given chemical equations show that CF2Cl2 is broken down into CF2Cl and Cl, which then reacts with O3 to form ClO and O2. This reaction cycle leads to the destruction of ozone. CF2Cl2 is a substance known as chlorofluorocarbon (CFC), which was widely used in aerosol propellants, refrigerants, and solvents. The release of CFCs into the atmosphere by human activities is the main cause of ozone depletion.

2. A destruição da camada de ozônio é um problema muito preocupante, pois essa região da estratosfera possui um papel importante na absorção de grande parte da radiação ultravioleta (UV) do Sol, que poderia causar grandes danos aos humanos. Entre esses danos, podemos apontar, exceto:

Câncer de pele.

Envelhecimento precoce da pele.

Osteoporose.

Redução da eficiência do sistema imunológico.

The destruction of the ozone layer is a major concern because it plays a crucial role in absorbing a significant amount of ultraviolet (UV) radiation from the sun, which can cause significant harm to humans. The listed options are all potential damages caused by exposure to UV radiation, except for osteoporosis. Osteoporosis is a condition characterized by weak and brittle bones, and it is not directly caused by UV radiation.

Explanation

The destruction of the ozone layer is a major concern because it plays a crucial role in absorbing a significant amount of ultraviolet (UV) radiation from the sun, which can cause significant harm to humans. The listed options are all potential damages caused by exposure to UV radiation, except for osteoporosis. Osteoporosis is a condition characterized by weak and brittle bones, and it is not directly caused by UV radiation.

3. (Fuvest-SP) Entidades ligadas à preservação ambiental têm exercido fortes pressões para a redução da produção de gases CFC (clorofluorcarbonos). Isto se deve principalmente ao fato de os CFC

Reagirem com H2O, produzindo ácidos e chuva ácida.

Reagirem espontaneamente com O2, produzindo CO2 e agravando o efeito estufa.

Escaparem para o espaço provocando o fenômeno da inversão térmica.

Produzirem sob a ação da luz átomos livres de Cloro, que reagem com o ozônio.

The correct answer is that CFCs produce free chlorine atoms under the action of light, which react with ozone. This is the main reason why entities related to environmental preservation have been exerting strong pressure for the reduction of CFC production. CFCs have been found to be a major contributor to the depletion of the ozone layer, as the chlorine atoms released from CFCs can react with ozone molecules, breaking them down and reducing the amount of ozone in the stratosphere. This depletion of the ozone layer has significant negative consequences for the environment and human health.

Explanation

The correct answer is that CFCs produce free chlorine atoms under the action of light, which react with ozone. This is the main reason why entities related to environmental preservation have been exerting strong pressure for the reduction of CFC production. CFCs have been found to be a major contributor to the depletion of the ozone layer, as the chlorine atoms released from CFCs can react with ozone molecules, breaking them down and reducing the amount of ozone in the stratosphere. This depletion of the ozone layer has significant negative consequences for the environment and human health.

4. (Enem-2012) O rótulo de um desodorante aerossol informa ao consumidor que o produto possui em sua composição os gases isobutano, butano e propano, dentre outras substâncias. Além dessa informação, o rótulo traz, ainda, a inscrição "Não contém CFC". As reações a seguir, que ocorrem na estratosfera, justificam a não utilização de CFC (clorofluorcarbono ou Freon) nesse desodorante: I) CF₂Cℓ₂ + UV → CF₂Cℓ• + Cℓ•
II) Cℓ• + O₃ → O₂ + CℓO• A preocupação com as possíveis ameaças à camada de ozônio (O₃) baseia-se na sua principal função: proteger a matéria viva na Terra dos efeitos prejudiciais dos raios solares ultravioleta. A absorção da radiação ultravioleta pelo ozônio estratosférico é intensa o suficiente para eliminar boa parte da fração de ultravioleta que é prejudicial à vida. A finalidade da utilização dos gases isobutano, butano e propano neste aerossol é:

Substituir o CFC, pois não reagem com o ozônio, servindo como gases propelentes em aerossóis.

Servir como propelentes, pois, como são muito reativos, capturam o Freon existente livre na atmosfera, impedindo a destruição do ozônio.

The gases isobutane, butane, and propane are used as propellants in aerosols as they do not react with ozone, making them a suitable alternative to CFCs. CFCs, such as CF2Cl2, can undergo reactions with UV radiation in the stratosphere, resulting in the release of chlorine radicals (Cl•). These chlorine radicals can then react with ozone (O3), leading to its depletion. By using non-reactive gases like isobutane, butane, and propane, the aerosol product can be propelled without contributing to ozone depletion.

Explanation

The gases isobutane, butane, and propane are used as propellants in aerosols as they do not react with ozone, making them a suitable alternative to CFCs. CFCs, such as CF2Cl2, can undergo reactions with UV radiation in the stratosphere, resulting in the release of chlorine radicals (Cl•). These chlorine radicals can then react with ozone (O3), leading to its depletion. By using non-reactive gases like isobutane, butane, and propane, the aerosol product can be propelled without contributing to ozone depletion.

5. (EsPCEx-SP) Tornou-se uma mania entre os alunos de diversas idades o hábito de carregar no lugar da antiga borracha o corretivo líquido. Muitos destes corretivos contêm DICLOROMETANO como solvente, que é prejudicial à saúde, por ser tóxico e muito volátil. Sua fórmula molecular é:

(C2H2)Cℓ2

CH2Cℓ2

C2Cℓ2

CH3CH2Cℓ

The correct answer is CH2Cℓ2. This is because the formula molecular for dichloromethane (corretivo líquido) is CH2Cℓ2, as stated in the passage. Dichloromethane is a toxic and volatile solvent that is harmful to health.

Explanation

The correct answer is CH2Cℓ2. This is because the formula molecular for dichloromethane (corretivo líquido) is CH2Cℓ2, as stated in the passage. Dichloromethane is a toxic and volatile solvent that is harmful to health.

6. (Fuvest - SP) Hidrocarbonetos halogenados, Usados em aerossóis, São também Responsáveis Pela Destruição da Camada de Ozônio da estratosfera. São Exemplos de Hidrocarbonetos halogenados:

CH2Cℓ2 e CH3CH3

CH3COCℓ e CH3OCH2Cℓ

CFCℓ3 e CF2Cℓ2

CH3NH2 e CFCℓ3

The correct answer is CFCℓ3 e CF2Cℓ2. These are examples of halogenated hydrocarbons that are used in aerosols and are also responsible for the destruction of the ozone layer in the stratosphere.

Explanation

The correct answer is CFCℓ3 e CF2Cℓ2. These are examples of halogenated hydrocarbons that are used in aerosols and are also responsible for the destruction of the ozone layer in the stratosphere.

7. (UEPA) A nomenclatura IUPAC dos compostos abaixo é: Exercício sobre nomenclatura

Iso-pentano; 2-cloropropano; álcool-sec-butílico.

2-metil-butano; cloreto de isopropila; 3-butanol.

Isopentil; 2-cloro-propano; álcool butílico.

2-metil-butano; 2-cloro-propano; 2-butanol.

The correct answer is 2-metil-butano; 2-cloro-propano; 2-butanol. This is because the IUPAC nomenclature for the compounds given is based on the longest carbon chain present in the molecule. In this case, the longest chain is a four-carbon chain, which is called butane. The presence of a methyl group on the second carbon atom of the chain gives the name 2-metil-butano. The presence of a chlorine atom on the second carbon atom of the chain gives the name 2-cloro-propano. And the presence of a hydroxyl group on the second carbon atom of the chain gives the name 2-butanol.

Explanation

The correct answer is 2-metil-butano; 2-cloro-propano; 2-butanol. This is because the IUPAC nomenclature for the compounds given is based on the longest carbon chain present in the molecule. In this case, the longest chain is a four-carbon chain, which is called butane. The presence of a methyl group on the second carbon atom of the chain gives the name 2-metil-butano. The presence of a chlorine atom on the second carbon atom of the chain gives the name 2-cloro-propano. And the presence of a hydroxyl group on the second carbon atom of the chain gives the name 2-butanol.