Foram encontradas 60 questões.
O decaimento radioativo é acompanhado por uma grande variação de energia, muito maior do que uma reação química e, por isso, é considerado uma fonte de energia eficiente. O decaimento de 1 mol de Urânio-238, conforme a equação abaixo, é 50 vezes maior que a queima do metano:
!$ ^{238}_{92}U \rightarrow ^{234}_{90}Th + ^4_2He !$
Considerando a velocidade da luz igual a 3,0 x 108 m s-1 e as massas dos núcleos de urânio iguais a 238,0003, de tório iguais a 233,9942 e de hélio iguais a 4,0015, a energia liberada nessa reação é de:
Provas
Uma pilha pode ser construída com dois eletrodos de hidrogênio: o primeiro com 1,00 atm de gás hidrogênio e o segundo com uma solução ácida de pH = 2,0. A 298 K, observa-se que a corrente elétrica flui do primeiro eletrodo para o segundo, e o potencial da célula é de:
(Dados: R=8,314J mol-1 K-1; F=96500sAmol-1)
Provas
A decomposição térmica do ciclopropano ocorre a 500°C, formando o propeno. A velocidade dessa reação ocorre por um mecanismo de primeira ordem. Se a constante de velocidade dessa reação, nessa temperatura, é de 7 x 10-4 s-1, o tempo necessário para decompor 3 x 103 em 2,1 x 10-3 mol dm-3 é de aproximadamente:
(Dados: In = 2,3 log; log 2 = 0,3; log 3 = 0,47; log 5 = 0,69; log7=0,84)
Provas
O biomimético [VO(acac)(bmimapy)]!$ C\ell O_4 !$ é um complexo sintetizado a partir do bis(acetilacetonato) de vanadila com o ligante bmimapy e pode ser caracterizado através da comparação de seus espectros no UV-vis, conforme representado a seguir:
É possível observar novas bandas em 320 nm e em 740 nm quando se compara o ligante com o complexo. Essas bandas são respectivamente:
Provas
O limoneno, produto natural encontrado na casca da laranja, é um composto com alto valor agregado, com diversas aplicações na indústria farmacêutica, e está representado a seguir:
Durante a síntese de uns desses materiais de interesse, o limoneno sofre hidrogenação catalítica, com o intuito de eliminar todas as suas insaturações. Em CNTP, o volume de hidrogênio necessário para obter o produto de interesse a partir de 8,5 9 de limoneno (teor de pureza de 80%) é de:
(Dados: MM limoneno = 136 g mol-1 ; Volume molar em CNTP = 22,4 L)
Provas
O brometo de benzila ou !$ \alpha !$-bromotolueno é um agente lacrimogênio que pode ser produzido a partir do benzeno em uma sequência de reações conforme o esquema simplificado a seguir:
Os reagentes A e C que completam o esquema reacional são:
Provas
Na síntese de amônia para a produção de fertilizantes, o nitrogênio e o hidrogênio molecular são misturados sob alta temperatura e pressão, a fim de se obter o maior rendimento do produto de interesse. Supondo que a reação seja realizada em um recipiente de 10 litros, que a quantidade inicial de nitrogênio e de hidrogênio seja, respectivamente, de 3 e 8 mols e que no final do processo conste a presença de 1 mol de nitrogênio, a constante de equilíbrio em termos de concentração (Kc) nessas condições de temperatura e pressão é de aproximadamente:
Provas
A concentração de iodeto em solução aquosa pode ser determinada diretamente por espectrometria molecular (UV-vis) em !$ \lambda_{max} = 226 !$ nm. Para isso, um técnico obteve o seguinte espectro usando uma cubeta de 0,5 cm:
Considerando que a absortividade molar do iodeto no referido comprimento de onda é igual a 12.486 L mol-1 cm-1 a concentração da espécie em mol L-1 é de aproximadamente:
Provas
Science, Technology & Innovation Policy in Brazil
In the field of Science, Technology & Innovation, the greatest challenge in Brazil has been in designing and implementing a long-term policy that enables scientific and technological development to reach the population in order to improve life quality.
This policy should have an effective impact on improving society's living conditions.
This is a process, which has been enhanced through time and has increasingly shown the great potential that public and private investment in Science, Technology & Innovation has for generating development and social integration. [...]
Electing Science, Technology & Innovation as a strategic choice for the country's development implies prioritizing investments in this sector, to recoup losses and swiftly advance in the production and dissemination of knowledge and innovation, particularly in relation to its incorporation in national production. This also means advocating on behalf of the importance of Science, Technology & Innovation as a factorthat integrates other government development policies. In this context, it is necessary for citizens to closely follow advancements and to be prepared to participate in decisions that are important for society.
When it comes to Science, Technology & Innovation management, Brazil relies on a structured system composed of a central coordinating body and development agencies in charge of defining and implementing development policies on science, technology, and innovation. The State and local levei Science, Technology & Innovation management systems follow the same model for development policies attuned to regional and local vocations.
Due to the country's dimensions, to difficulties encountered in its management structure, and, above ali, to implementing national policies capable of simultaneously addressing varied regional needs, the scientific and technological knowledge produced is still slow to produce significant changes in the social inequities found in some regions. Therefore, the problems faced by Brazil in the fields of Science, Technology & Innovation are complex and can hardly be solved in the short term.
Adapted from:
https:/Ien.unesco.org/fieldoffice/brasilia/expertise/science-technology-
innovation Access on February 11,2022.
In "Therefore, the problems faced by Brazil in the fields of Science, Technology & Innovation are complex and can hardly be solved in the short term", the highlighted expression introduces:
Provas
Science, Technology & Innovation Policy in Brazil
In the field of Science, Technology & Innovation, the greatest challenge in Brazil has been in designing and implementing a long-term policy that enables scientific and technological development to reach the population in order to improve life quality.
This policy should have an effective impact on improving society's living conditions.
This is a process, which has been enhanced through time and has increasingly shown the great potential that public and private investment in Science, Technology & Innovation has for generating development and social integration. [...]
Electing Science, Technology & Innovation as a strategic choice for the country's development implies prioritizing investments in this sector, to recoup losses and swiftly advance in the production and dissemination of knowledge and innovation, particularly in relation to its incorporation in national production. This also means advocating on behalf of the importance of Science, Technology & Innovation as a factorthat integrates other government development policies. In this context, it is necessary for citizens to closely follow advancements and to be prepared to participate in decisions that are important for society.
When it comes to Science, Technology & Innovation management, Brazil relies on a structured system composed of a central coordinating body and development agencies in charge of defining and implementing development policies on science, technology, and innovation. The State and local levei Science, Technology & Innovation management systems follow the same model for development policies attuned to regional and local vocations.
Due to the country's dimensions, to difficulties encountered in its management structure, and, above ali, to implementing national policies capable of simultaneously addressing varied regional needs, the scientific and technological knowledge produced is still slow to produce significant changes in the social inequities found in some regions. Therefore, the problems faced by Brazil in the fields of Science, Technology & Innovation are complex and can hardly be solved in the short term.
Adapted from:
https:/Ien.unesco.org/fieldoffice/brasilia/expertise/science-technology-
innovation Access on February 11,2022.
Choose the alternative in which the words can properly substitute the highlighted terms in the sentence "Electing Science, Technology & Innovation as a strategic choice for the country's development implies prioritizing investments in this sector, to recoup losses and swiftly advance in the production and dissemination of knowledge and innovation ... "
Provas
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