Foram encontradas 60 questões.
O diagrama de McCabe-Thiele é usado na separação de uma mistura binária para calcular o número de estágios de equilíbrio em uma torre de destilação, utilizando-se um gráfico y versus x, construído para o componente mais volátil.
Nesse diagrama, a(s)
Nesse diagrama, a(s)
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A reação 2 A → B, em fase líquida, cuja cinética obedece ao comportamento de uma reação elementar, é conduzida em um reator em batelada de 100 L. No início de cada batelada, a massa reacional contém 5,0 mol/L de A e 0,5 mol/L de B. Sabendo-se que, nas condições de reação, a constante de velocidade da reação (k) é igual a 0,1 L∙mol-1
∙min-1 , e as massas molares de A e B são, respectivamente, 20 kg/kmol e 40 kg/kmol, o valor inicial da derivada da massa de B em relação ao tempo, em kg/min, é
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Um processo químico é baseado na reação A → B + C, elementar, exotérmica e irreversível. Essa reação ocorre em um reator tipo tanque agitado (CSTR), em fase líquida, na temperatura de 200 ºC, com conversão de 40%. Se a temperatura de operação do reator aumentar para 220 ºC, a conversão irá
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Considere a afirmação abaixo.
Se uma lâmpada está queimada então não acende.
Uma afirmação logicamente equivalente à apresentada acima é:
Se uma lâmpada está queimada então não acende.
Uma afirmação logicamente equivalente à apresentada acima é:
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Três irmãs brincavam no jardim quando a avó apareceu e perguntou: “Que dia é hoje?"
A mais nova disse: Ontem foi quarta-feira.
A do meio disse: Hoje não é sexta-feira.
A mais velha disse: Amanhã será sábado.
Sabendo-se que uma das crianças mentiu e as outras disseram a verdade, o dia da semana em que esta história ocorreu foi
A mais nova disse: Ontem foi quarta-feira.
A do meio disse: Hoje não é sexta-feira.
A mais velha disse: Amanhã será sábado.
Sabendo-se que uma das crianças mentiu e as outras disseram a verdade, o dia da semana em que esta história ocorreu foi
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Na Inglaterra do século IX, as pessoas utilizavam como dinheiro o
xelim e o penny, cujo plural é pence. O valor do penny era muito menor que o do xelim. Naquela época, o rei Alfredo cunhou moedas de ouro, de valor muito maior que o xelim.
O escritor B. Cornwell contou em um de seus livros que, em um casamento naquela época, o pai da noiva exigiu do noivo o pagamento de 33 xelins, quantia equivalente a 396 pence, para que o casamento fosse realizado. O noivo pagou então ao pai da noiva a mesma quantia na forma de uma moeda de ouro mais 36 pence, e o casamento foi realizado.
Nesse sistema monetário, uma moeda de ouro era equivalente a quantos xelins?
O escritor B. Cornwell contou em um de seus livros que, em um casamento naquela época, o pai da noiva exigiu do noivo o pagamento de 33 xelins, quantia equivalente a 396 pence, para que o casamento fosse realizado. O noivo pagou então ao pai da noiva a mesma quantia na forma de uma moeda de ouro mais 36 pence, e o casamento foi realizado.
Nesse sistema monetário, uma moeda de ouro era equivalente a quantos xelins?
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Uma professora recebeu uma caixa de lápis para distribuir igualmente aos seus alunos. Se a professora desse 4 lápis a cada aluno, sobrariam 17 lápis. Entretanto, se iniciasse a distribuição dando 5 lápis a cada um, os dois últimos alunos nada ganhariam.
O número de lápis da caixa é
O número de lápis da caixa é
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A figura acima mostra uma ficha quadrada dividida em 5 regiões: um quadrado central e quatro trapézios iguais. Essa ficha será pintada de forma que duas regiões vizinhas não tenham a mesma cor. Escolhidas as cores das regiões, giros na ficha não a tornam diferente. Se 4 cores estão disponíveis, de quantos modos distintos essa ficha pode ser pintada?
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Cleaning up a spill
Written by Laura Hill
Water and oil don’t mix. We see this every day; just try washing olive oil off your hands without soap or washing your face in the morning with only water. It just doesn’t work!
When an oil spill occurs in the ocean, like the catastrophe in the Gulf of Mexico, what do scientists do to clean up the toxic mess? There are a number of options for an oil spill cleanup and most efforts use a combination of many techniques. The fact that oil and water don’t mix is a blessing and a curse. If oil mixed with water, it would be difficult to divide the two.
Crude oil is less dense than water; it spreads out to make a very thin layer (about one millimetre thick) that floats on top of the water. This is good because we can tell what is water and what is oil. It is also bad, because it means the oil can spread really quickly and cover a very large area, which becomes difficult to manage. Combined with wind, ocean currents and waves, oil spill cleanup starts to get really tricky.
Chemical dispersants can be used to break up big oil slicks into small oil droplets. They work like soaps by emulsifying the hydrophobic (waterrepelling) oil in the water. These small droplets can degrade in the ecosystem quicker than the big oil slick. But unfortunately, this means that marine life of all sizes ingest these toxic, broken-down particles and chemicals.
If the oil is thick enough, it could be set fire, a process called “in situ burning”. Because the oil is highly flammable and floats on top of the water, it is very easy to set it alight. It’s not environmentallyfriendly though; the combustion of oil releases thick smoke that contains greenhouse gases and other dangerous air pollutants.
Some techniques can contain and recapture spilled oil without changing its chemical composition. Booms float on top of the water and act as barriers to the movement of oil. Once the oil is controlled, it can be gathered using sorbents. “Sorbent” is a fancy word for sponge. These sponges absorb the oil and allow it to be collected by siphoning it off the water.
However, weather and sea conditions can prevent and obstruct the use of booms, sorbents and in situ burning. Imagine trying to perform these operations on the open sea with wind, waves and water currents moving the oil (and your boat!) around on the water.
What about the plants and animals? It’s easy to forget about the organisms in the sea that are under water. Out of sight, out of mind! There is not much we can do to help them. But when oil reaches the shore it impacts sensitive coastal environments including the many fish, bird, amphibian, reptilian, and crustaceanspecies that live there. We have easy access to these areas and there are some things we can do to clean up. For the plants, it is often a matter of setting them on fire, or leaving them to degrade the oil naturally. Sometimes, we can spray the oil with nutrients (phosphorus and nitrogen) that can encourage the growth of specialized microorganisms. For species that can tolerate our soaps, manpower is needed to wash every affected animal. Yet, if the animal has tried to lick itself clean, it can die from ingesting the toxic oil.
Unfortunately, there can be many negative economic and social impacts, in addition to the environmental impacts of oil spills and, as you’ve just read, the clean up techniques are far from perfect. Prevention is the very best cleanup technique we have. http://www.curiocity.ca/everyday-science/environme... -cleaning-up-a-spill.html, retrieved on Dec 10, 2010
The main purpose of the text is toWritten by Laura Hill
Water and oil don’t mix. We see this every day; just try washing olive oil off your hands without soap or washing your face in the morning with only water. It just doesn’t work!
When an oil spill occurs in the ocean, like the catastrophe in the Gulf of Mexico, what do scientists do to clean up the toxic mess? There are a number of options for an oil spill cleanup and most efforts use a combination of many techniques. The fact that oil and water don’t mix is a blessing and a curse. If oil mixed with water, it would be difficult to divide the two.
Crude oil is less dense than water; it spreads out to make a very thin layer (about one millimetre thick) that floats on top of the water. This is good because we can tell what is water and what is oil. It is also bad, because it means the oil can spread really quickly and cover a very large area, which becomes difficult to manage. Combined with wind, ocean currents and waves, oil spill cleanup starts to get really tricky.
Chemical dispersants can be used to break up big oil slicks into small oil droplets. They work like soaps by emulsifying the hydrophobic (waterrepelling) oil in the water. These small droplets can degrade in the ecosystem quicker than the big oil slick. But unfortunately, this means that marine life of all sizes ingest these toxic, broken-down particles and chemicals.
If the oil is thick enough, it could be set fire, a process called “in situ burning”. Because the oil is highly flammable and floats on top of the water, it is very easy to set it alight. It’s not environmentallyfriendly though; the combustion of oil releases thick smoke that contains greenhouse gases and other dangerous air pollutants.
Some techniques can contain and recapture spilled oil without changing its chemical composition. Booms float on top of the water and act as barriers to the movement of oil. Once the oil is controlled, it can be gathered using sorbents. “Sorbent” is a fancy word for sponge. These sponges absorb the oil and allow it to be collected by siphoning it off the water.
However, weather and sea conditions can prevent and obstruct the use of booms, sorbents and in situ burning. Imagine trying to perform these operations on the open sea with wind, waves and water currents moving the oil (and your boat!) around on the water.
What about the plants and animals? It’s easy to forget about the organisms in the sea that are under water. Out of sight, out of mind! There is not much we can do to help them. But when oil reaches the shore it impacts sensitive coastal environments including the many fish, bird, amphibian, reptilian, and crustaceanspecies that live there. We have easy access to these areas and there are some things we can do to clean up. For the plants, it is often a matter of setting them on fire, or leaving them to degrade the oil naturally. Sometimes, we can spray the oil with nutrients (phosphorus and nitrogen) that can encourage the growth of specialized microorganisms. For species that can tolerate our soaps, manpower is needed to wash every affected animal. Yet, if the animal has tried to lick itself clean, it can die from ingesting the toxic oil.
Unfortunately, there can be many negative economic and social impacts, in addition to the environmental impacts of oil spills and, as you’ve just read, the clean up techniques are far from perfect. Prevention is the very best cleanup technique we have. http://www.curiocity.ca/everyday-science/environme... -cleaning-up-a-spill.html, retrieved on Dec 10, 2010
Provas
Questão presente nas seguintes provas
Cleaning up a spill
Written by Laura Hill
Water and oil don’t mix. We see this every day; just try washing olive oil off your hands without soap or washing your face in the morning with only water. It just doesn’t work!
When an oil spill occurs in the ocean, like the catastrophe in the Gulf of Mexico, what do scientists do to clean up the toxic mess? There are a number of options for an oil spill cleanup and most efforts use a combination of many techniques. The fact that oil and water don’t mix is a blessing and a curse. If oil mixed with water, it would be difficult to divide the two.
Crude oil is less dense than water; it spreads out to make a very thin layer (about one millimetre thick) that floats on top of the water. This is good because we can tell what is water and what is oil. It is also bad, because it means the oil can spread really quickly and cover a very large area, which becomes difficult to manage. Combined with wind, ocean currents and waves, oil spill cleanup starts to get really tricky.
Chemical dispersants can be used to break up big oil slicks into small oil droplets. They work like soaps by emulsifying the hydrophobic (waterrepelling) oil in the water. These small droplets can degrade in the ecosystem quicker than the big oil slick. But unfortunately, this means that marine life of all sizes ingest these toxic, broken-down particles and chemicals.
If the oil is thick enough, it could be set fire, a process called “in situ burning”. Because the oil is highly flammable and floats on top of the water, it is very easy to set it alight. It’s not environmentallyfriendly though; the combustion of oil releases thick smoke that contains greenhouse gases and other dangerous air pollutants.
Some techniques can contain and recapture spilled oil without changing its chemical composition. Booms float on top of the water and act as barriers to the movement of oil. Once the oil is controlled, it can be gathered using sorbents. “Sorbent” is a fancy word for sponge. These sponges absorb the oil and allow it to be collected by siphoning it off the water.
However, weather and sea conditions can prevent and obstruct the use of booms, sorbents and in situ burning. Imagine trying to perform these operations on the open sea with wind, waves and water currents moving the oil (and your boat!) around on the water.
What about the plants and animals? It’s easy to forget about the organisms in the sea that are under water. Out of sight, out of mind! There is not much we can do to help them. But when oil reaches the shore it impacts sensitive coastal environments including the many fish, bird, amphibian, reptilian, and crustaceanspecies that live there. We have easy access to these areas and there are some things we can do to clean up. For the plants, it is often a matter of setting them on fire, or leaving them to degrade the oil naturally. Sometimes, we can spray the oil with nutrients (phosphorus and nitrogen) that can encourage the growth of specialized microorganisms. For species that can tolerate our soaps, manpower is needed to wash every affected animal. Yet, if the animal has tried to lick itself clean, it can die from ingesting the toxic oil.
Unfortunately, there can be many negative economic and social impacts, in addition to the environmental impacts of oil spills and, as you’ve just read, the clean up techniques are far from perfect. Prevention is the very best cleanup technique we have. http://www.curiocity.ca/everyday-science/environme... -cleaning-up-a-spill.html, retrieved on Dec 10, 2010
According to the text, “in situ burning" (line 29) isWritten by Laura Hill
Water and oil don’t mix. We see this every day; just try washing olive oil off your hands without soap or washing your face in the morning with only water. It just doesn’t work!
When an oil spill occurs in the ocean, like the catastrophe in the Gulf of Mexico, what do scientists do to clean up the toxic mess? There are a number of options for an oil spill cleanup and most efforts use a combination of many techniques. The fact that oil and water don’t mix is a blessing and a curse. If oil mixed with water, it would be difficult to divide the two.
Crude oil is less dense than water; it spreads out to make a very thin layer (about one millimetre thick) that floats on top of the water. This is good because we can tell what is water and what is oil. It is also bad, because it means the oil can spread really quickly and cover a very large area, which becomes difficult to manage. Combined with wind, ocean currents and waves, oil spill cleanup starts to get really tricky.
Chemical dispersants can be used to break up big oil slicks into small oil droplets. They work like soaps by emulsifying the hydrophobic (waterrepelling) oil in the water. These small droplets can degrade in the ecosystem quicker than the big oil slick. But unfortunately, this means that marine life of all sizes ingest these toxic, broken-down particles and chemicals.
If the oil is thick enough, it could be set fire, a process called “in situ burning”. Because the oil is highly flammable and floats on top of the water, it is very easy to set it alight. It’s not environmentallyfriendly though; the combustion of oil releases thick smoke that contains greenhouse gases and other dangerous air pollutants.
Some techniques can contain and recapture spilled oil without changing its chemical composition. Booms float on top of the water and act as barriers to the movement of oil. Once the oil is controlled, it can be gathered using sorbents. “Sorbent” is a fancy word for sponge. These sponges absorb the oil and allow it to be collected by siphoning it off the water.
However, weather and sea conditions can prevent and obstruct the use of booms, sorbents and in situ burning. Imagine trying to perform these operations on the open sea with wind, waves and water currents moving the oil (and your boat!) around on the water.
What about the plants and animals? It’s easy to forget about the organisms in the sea that are under water. Out of sight, out of mind! There is not much we can do to help them. But when oil reaches the shore it impacts sensitive coastal environments including the many fish, bird, amphibian, reptilian, and crustaceanspecies that live there. We have easy access to these areas and there are some things we can do to clean up. For the plants, it is often a matter of setting them on fire, or leaving them to degrade the oil naturally. Sometimes, we can spray the oil with nutrients (phosphorus and nitrogen) that can encourage the growth of specialized microorganisms. For species that can tolerate our soaps, manpower is needed to wash every affected animal. Yet, if the animal has tried to lick itself clean, it can die from ingesting the toxic oil.
Unfortunately, there can be many negative economic and social impacts, in addition to the environmental impacts of oil spills and, as you’ve just read, the clean up techniques are far from perfect. Prevention is the very best cleanup technique we have. http://www.curiocity.ca/everyday-science/environme... -cleaning-up-a-spill.html, retrieved on Dec 10, 2010
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Cadernos
Caderno Container