Questões - ITA | Gabarito e resoluções

(ITA - 2016) Considere que 20 g de tiossulfato de potssio com pureza de 95% reagem com cido clordrico em excesso, formando 3,2 g de um slido de colorao amarela. Assinale a alternativa que melhor representa o rendimento desta reao.

(ITA - 2016 - 1 FASE) Um estudante usa um tubo de Pitot esquematizado na figura para medir a velocidade do ar em um tnel de vento. A densidade do ar igual a 1,2 kg/m3 e a densidade do lquido 1,2104 kg/m3 , sendo h = 10 cm. Nessas condies a velocidade do ar aproximadamente igual a:

(ITA - 2016 - 1 FASE) Sejam uma circunferncia de raio 4 cm e uma corda em de comprimento 4 cm. As tangentes a em P e em Q interceptam-se no ponto R exterior a . Ento, a rea do tringulo PQR, em cm2 , igual a

(ITA - 2016 - 1 FASE) Balo com gs Hlio inicialmente a 27◦C de temperatura e presso de 1,0 atm, as mesmas do ar externo, sobe at o topo de uma montanha, quando o gs se resfria a 23◦C e sua presso reduz-se a 0,33 de atm, tambm as mesmas do ar externo. Considerando invarivel a acelerao da gravidade na subida, a razo entre as foras de empuxo que atuam no balo nestas duas posies :

(ITA - 2016 - 1 FASE) Teflon was Invented by Accident Today I found out Teflon was invented by accident. The man who accidentally invented it was Dr. Roy Plunkett. After receiving his BA, MS, and eventually PhD in organic chemistry, Dr. Plunkett took a job with DuPont, in Jackson New Jersey. He was subsequently assigned to work on synthesizing various new forms of refrigerant, trying to find a non-toxic alternative to refrigerants like sulfur dioxide and ammonia. According to DuPont, in 1938, 27 year old Dr. Plunkett and his assistant, Jack Rebok, were experimenting with one such potential alternative refrigerant, tetrafluorethylene (TFE). Dr. Plunkett subsequently created around 100 pounds of TFE and stored the gas in small cylinders. On April 6, 1938, upon opening the valve on one of the pressurized cylinders of TFE that had previously been frozen, nothing came out, even though by its weight, it seemed to still be full. Dr. Plunkett and Jack Rebok then decided to investigate further by cutting the cylinder open. Once they managed to get it open, they discovered that the TFE gas inside had polymerized into a waxy white powder, polytetrafluoroethylene (PTFE) resin. Ever the scientist, Plunkett then proceeded to run tests on this new substance to see if it had any unique or useful properties. Four of the most important properties of this substance discovered were that it was extremely slippery (one of the slipperiest substances known to man), non-corrosive, chemically stable, and that it had an extremely high melting point. These properties were deemed interesting enough that the study of the substance was transferred to DuPonts Central Research Department and assigned to chemists that had special experience in polymer research and development, while Dr. Plunkett was then promoted and transferred to a separate division that produced tetraethyl (sic), used to boost gasoline octane levels. Three years later, the process and name of Teflon were patented and trademarked. Four years after that, Teflon first began being sold, initially only used for various industrial and military applications due to the expense of producing TFE. By the 1960s, various forms of Teflon were being used in a variety of applications, such as stain repellant in fabrics and electrical wire insulation. It was also in the 1960s that Teflon began being used in its most publicly known application, as a coating for non-stick pans. Today, Teflon or other brands of the same product are also used in windshield wipers; carpets and furniture (as a stain repellant); light bulbs; coating on glasses; in various hair products; in semiconductor manufacturing; automotive lubricant; igniters for solid-fuel rocket propellants; and in infrared decoy flares, among other things. Adaptado de www.todayIfoundout.com (acesso em 19/07/2015). De acordo com o texto

(ITA - 2016 - 1 Fase) Considere as entalpias padro de formao dos seguintes compostos: Sabendo que a capacidade calorfica da gua, presso constante, vale 75,9 Jmol1 e que sua entalpia de vaporizao igual a 40,66 kJmol1, assinale a alternativa que melhor corresponda ao nmero de mols de metano necessrios para vaporizar 1 L de gua pura, cuja temperatura inicial 25 C, ao nvel do mar.

(ITA - 2016 - 1 FASE) Teflon was Invented by Accident Today I found out Teflon was invented by accident. The man who accidentally invented it was Dr. Roy Plunkett. After receiving his BA, MS, and eventually PhD in organic chemistry, Dr. Plunkett took a job with DuPont, in Jackson New Jersey. He was subsequently assigned to work on synthesizing various new forms of refrigerant, trying to find a non-toxic alternative to refrigerants like sulfur dioxide and ammonia. According to DuPont, in 1938, 27 year old Dr. Plunkett and his assistant, Jack Rebok, were experimenting with one such potential alternative refrigerant, tetrafluorethylene (TFE). Dr. Plunkett subsequently created around 100 pounds of TFE and stored the gas in small cylinders. On April 6, 1938, upon opening the valve on one of the pressurized cylinders of TFE that had previously been frozen, nothing came out, even though by its weight, it seemed to still be full. Dr. Plunkett and Jack Rebok then decided to investigate further by cutting the cylinder open. Once they managed to get it open, they discovered that the TFE gas inside had polymerized into a waxy white powder, polytetrafluoroethylene (PTFE) resin. Ever the scientist, Plunkett then proceeded to run tests on this new substance to see if it had any unique or useful properties. Four of the most important properties of this substance discovered were that it was extremely slippery (one of the slipperiest substances known to man), non-corrosive, chemically stable, and that it had an extremely high melting point. These properties were deemed interesting enough that the study of the substance was transferred to DuPonts Central Research Department and assigned to chemists that had special experience in polymer research and development, while Dr. Plunkett was then promoted and transferred to a separate division that produced tetraethyl (sic), used to boost gasoline octane levels. Three years later, the process and name of Teflon were patented and trademarked. Four years after that, Teflon first began being sold, initially only used for various industrial and military applications due to the expense of producing TFE. By the 1960s, various forms of Teflon were being used in a variety of applications, such as stain repellant in fabrics and electrical wire insulation. It was also in the 1960s that Teflon began being used in its most publicly known application, as a coating for non-stick pans. Today, Teflon or other brands of the same product are also used in windshield wipers; carpets and furniture (as a stain repellant); light bulbs; coating on glasses; in various hair products; in semiconductor manufacturing; automotive lubricant; igniters for solid-fuel rocket propellants; and in infrared decoy flares, among other things. Adaptado de www.todayIfoundout.com (acesso em 19/07/2015). De acordo com o texto, o tipo de indstria que no se beneficia com as propriedades do Teflon a indstria

(ITA - 2016 - 1 FASE) Se a reta de equao x = a divide o quadriltero cujos vrtices so (0, 1), (2, 0), (4, 0) e (6, 4) em duas regies de mesma rea, ento o valor de a igual a

(ITA - 2016 - 1 Fase) Sabendo que a funo trabalho do zinco metlico 5,82 10-19 J , assinale a opo que apresenta a energia cintica mxima, em joules, de um dos eltrons emitidos, quando luz de comprimento de onda igual a 140 nm atinge a superfcie do zinco.

(ITA - 2016 - 1 FASE) Um corpo flutua estavelmente em um tanque contendo dois lquidos imiscveis, um com o dobro da densidade do outro, de tal forma que as interfaces lquido/lquido e lquido/ar dividem o volume do corpo exatamente em trs partes iguais. Sendo completamente removido o lquido mais leve, qual proporo do volume do corpo permanece imerso no lquido restante?

(ITA - 2016 - 1 FASE) Seja p o polinmio dado por p(x) = x8 + xm 2xn , em que os expoentes 8, m, n formam, nesta ordem, uma progresso geomtrica cuja soma dos termos igual a 14. Considere as seguintes afirmaes: I. x = 0 uma raiz dupla de p. II. x = 1 uma raiz dupla de p. III. p tem quatro razes com parte imaginria no nula. Destas, (so) verdadeira(s)

(ITA - 2016 - 1 FASE) A figura mostra uma placa fina de peso P dobrada em ngulo reto e disposta sobre uma esfera fixa de raio a. O coeficiente de atrito mnimo entre estes objetos para que a placa no escorregue :

(ITA - 2016 - 1 FASE) De acordo com o texto

(ITA - 2016 - 1 Fase) Considerando um gs monoatmico ideal, assinale a opo que contm o grfico que melhor representa como a energia cintica mdia (Ec) das partculas que compem este gs veria em funo da temperatura absoluta (T) deste gs.

(ITA - 2016 - 1 FASE) Seja ABC um tringulo equiltero e suponha que M e N so pontos pertencentes ao lado tais que BM = MN = NC. Sendo a medida, em radianos, do ngulo MN , ento o valor de cos