Revisão balanceamento - 
Autor: Clarissa Carús de Oliveira | Publicado: 2015-03-11T08:12:00-07:00


1. (UFRGS) Completando a reação&nbsp;&nbsp;&nbsp;&nbsp; 



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__Ba(OH)2&nbsp; &nbsp;--&gt; &nbsp; &nbsp;________&nbsp; +__H2O





e acertando os coeficientes, a alternativa que
corresponde aos coeficientes estequiométricos corretos é

A) 2, 3, 3, 6&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 

B) 2, 3, 1, 6&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 

C) 1, 1, 3, 1

D) 1, 3, 1, 1&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 

E) 1, 1, 1, 1





2. (UFRGS) Entre as equações
químicas abaixo, aquela que não representa uma reação química de acordo
com a Lei da Conservação da Massa é:

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<![endif]--><!--[if !vml]--><!--[endif]-->A) (NH4)2Cr2O7&nbsp; --&gt; &nbsp; &nbsp; &nbsp;N2&nbsp;
+&nbsp; Cr2O3&nbsp; +&nbsp;&nbsp;
4H2O

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<![endif]--><!--[if !vml]--><!--[endif]-->B) Al2(SO4)3&nbsp;
+ 6NaOH&nbsp; --&gt; &nbsp; &nbsp;&nbsp;2Al(OH)3&nbsp; + 3Na2SO4

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<![endif]--><!--[if !vml]--><!--[endif]-->C) 3P +&nbsp; 5HNO3 +&nbsp; 2H2O&nbsp; &nbsp; --&gt; &nbsp; &nbsp;&nbsp;3H3PO4&nbsp; +&nbsp;&nbsp;
5NO

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<![endif]--><!--[if !vml]-->- &nbsp;--<!--[endif]-->D) MnO2&nbsp; +&nbsp;
2HCl&nbsp; --&gt; &nbsp; &nbsp; &nbsp;MnCl2&nbsp; +&nbsp;
2H2O&nbsp; +&nbsp; Cl2

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<![endif]--><!--[if !vml]--><!--[endif]-->E) Ca(OH)2 &nbsp;+&nbsp; H2SO4&nbsp; &nbsp;--&gt; &nbsp; &nbsp; &nbsp; &nbsp;CaSO4&nbsp; +&nbsp;
2H2O





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<![endif]--><!--[if !vml]--><!--[endif]-->3. (PUCRS) A
equação não-balanceada que representa o processo de obtenção do alumínio
a partir da bauxita é

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Al2O3 +&nbsp;&nbsp; C&nbsp; &nbsp;--&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;CO2&nbsp; + &nbsp;Al

O número de mols de
gás carbônico e alumínio produzido a partir de 4 mols de Al2O3
é, respectivamente

A) 3 e 2&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 

B) 1 e 4&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 

C) 2 e 3&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 

D) 6 e 8&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 

E) 6 e 4.





4. (UFSM) O escurecimento de objetos de prata deve-se à formação
de Ag2S. A remoção da camada escura pode ser feita com o emprego de
alumínio, o que é representado pela equação não-balanceada



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<![endif]--><!--[if !vml]-->&nbsp; &nbsp; --<!--[endif]-->Al(s)&nbsp; +&nbsp;&nbsp;&nbsp;&nbsp;
Ag2S(s)&nbsp;
+&nbsp;&nbsp;&nbsp;&nbsp; H2O(l)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;Al(OH)3(s)&nbsp; +&nbsp;&nbsp;&nbsp; H2S(g)&nbsp; +&nbsp;&nbsp;&nbsp;&nbsp;
Ag(s)



Após
o balanceamento, pode-se concluir que a som dos coeficientes dessa equação é

A)
22&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 

B)
17&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 

C)
16&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 

D)
13&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 

E)
11