Tag: endothermic reactions

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Multiple choice chemistry endothermic and exothermic reactions endothermic reactions what are enthalpy changes energy change in chemical reactions

During the reaction of some metals with dilute hydrochloric acid, the following observations were made. The temperature of the reaction mixture rises when aluminium (Al) is added mainly because :

                       

  1. Heat is evolved

  2. Due to the catalyst

  3. It is an endothermic reaction.

  4. It is an exothermic reaction.
Reveal answer Fill a bubble to check yourself
A,D Correct answer
Explanation

The temperature of the reaction mixture rises beacause, the following exothermic reaction takes place:

$2Al(s)  +  6HCl(aq)  \rightarrow   2AlCl _{3}(aq)  +  3H _{2}(g)  +  heat$

Multiple choice chemistry endothermic and exothermic reactions endothermic reactions what are enthalpy changes energy change in chemical reactions

Decomposition of ferrous sulphate is a/an:

  1. precipitation reactions

  2. exothermic reactions

  3. endothermic reactions

  4. Synthesis reactions
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Decomposition of ferrous sulphate is an endothermic reaction as it involves absorption of heat to form ferric oxide ($Fe _{2}O _{3}$), sulphur dioxide ($SO _{2}$) and sulphur trioxide ($SO _{3}$). The equation for this reaction can be written as:
$ 2FeSO _{4}(s)  \overset{heat}{\rightarrow}  Fe _{2}O _{3}(s)  +  SO _{2}(g)  +  SO _{3}(g)$

Multiple choice chemistry endothermic and exothermic reactions endothermic reactions what are enthalpy changes energy change in chemical reactions
During the reaction of some metals with dilute hydrochloric acid,
following observations were made. 
 
The reaction of sodium metal is found to be highly explosive because:

  1. Heat is evolved

  2. Due to the catalyst

  3. It is an endothermic reaction.

  4. It is an exothermic reaction.
Reveal answer Fill a bubble to check yourself
A,D Correct answer
Explanation

Reaction of sodium with hydrochloric acid is highly exothermic one and therefore explosive in nature.
$2Na(s)  +  2HCl(aq)  \rightarrow   2NaCl(aq)  +  H _{2}(g)$  +  heat

Multiple choice chemistry endothermic and exothermic reactions endothermic reactions what are enthalpy changes energy change in chemical reactions

Dilution of sulphuric acid is a/an:

  1. synthesis reaction

  2. exothermic reaction

  3. endothermic reaction

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Dilution of sulphuric acid with water is a highly exothermic process as it occurs with the evolution of heat. The equation for this reaction  can be wriiten as:
$H _{2}SO _{4}  +  2H _{2}O  \rightarrow   2H _{3}O^{+}  +  SO _{4}^{2-}  +  heat$

Multiple choice chemistry endothermic and exothermic reactions endothermic reactions what are enthalpy changes energy change in chemical reactions

Which of the following are endothermic process?

  1. boiling of water

  2. dissolving salts in water
  3. dissolving conc. $H _2SO _4$ in water

  4. evaporation of water
Reveal answer Fill a bubble to check yourself
A,B,D Correct answer
Explanation
  1. Boiling of water would be an endothermic process because the system (water) is absorbing heat to turn into vapour. Hence both option 1 $ 3 are endothermic.
     And the reverse process would therefore be exothermic.

    2. Addition of Conc. acids to water is an exothermic reaction.
Multiple choice chemistry endothermic and exothermic reactions endothermic reactions what are enthalpy changes energy change in chemical reactions

Chemical reactions occur with absorption of heat energy are called:

  1. precipitation reactions

  2. exothermic reactions

  3. endothermic reactions

  4. synthesis reactions
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The term endothermic process describes a process or reaction in which the system absorbs energy from its surroundings in the form of heat where in case of exothermic it releases energy to the surroundings. 

Multiple choice chemistry endothermic and exothermic reactions endothermic reactions what are enthalpy changes energy change in chemical reactions

Which of the following is/are endothermic reactions?

  1. $CaCO _{3}\rightarrow CaO+CO _{2}$
  2. $CH _{4}+2O _{2}\rightarrow CO _{2}+2H _{2}O$
  3. $2HgO\rightarrow 2Hg+O _{2}$
  4. $2H _{2}+O _{2}\rightarrow 2H _{2}O$
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Explanation
$CaCO _{3}\rightarrow CaO+CO _{2}$
is a decomposition reaction and requires energy for breaking bonds. Its an endothermic reaction.
$CH _{4}+2O _{2}\rightarrow CO _{2}+2H _{2}O$
Its a combustion reaction hence releases energy and is an exothermic reaction
$2HgO\rightarrow 2Hg+O _{2}$
is a decomposition reaction and requires energy for breaking bonds. Its an endothermic reaction.
$2H _{2}+O _{2}\rightarrow 2H _{2}O$
Its a combustion reaction hence releases energy and is an exothermic reaction
Thus A and D are endothermic reactions. Option A and D are correct
Multiple choice chemistry endothermic and exothermic reactions endothermic reactions what are enthalpy changes energy change in chemical reactions

In endothermic reactions:

  1. reactants have more energy than products

  2. reactants have less energy than products

  3. reactants and products have same energy

  4. reactants have lower temperature than products
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

An endothermic occurs if the products have a higher energy level than the reactants and $\Delta H$ will be positive. In other words, reactants have lesser energy than products.

In an exothermic reaction, the reacting mixture absorbs heat from the surroundings. Therefore, the reactants will have higher energy than the product here.

So the answer is option B.

Multiple choice chemistry endothermic and exothermic reactions endothermic reactions what are enthalpy changes energy change in chemical reactions
For per gram reactant, the maximum quantity of ${ N } _{ 2 }$ gas is produced in which of the following thermal decomposition reaction? (Given: Atomic wt. Cr=52 u, Ba=137 u)
  1. $(NH _4) _2Cr _2O _7(s) \rightarrow N _2(g) + 4H _2O(g)+Cr _2O _3(s)$
  2. $2NH _4NO _3(s) \rightarrow 2N _2(g) + 4H _2O(g)+O _2(g)$
  3. $Ba(N _3) _2(s) \rightarrow Ba(s) + 3N _2(g)$
  4. $2NH _3(g) \rightarrow N _2(g) + 3H _2(g)$
Reveal answer Fill a bubble to check yourself
B Correct answer