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

Which term means a reaction which releases energy?

  1. Exothermic

  2. Particle Size

  3. Endothermic

  4. Catalyst
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

An exothermic reaction is a chemical reaction that releases energy by light or heat. It is the opposite of an endothermic reaction. Expressed in a chemical equation: reactants → products + energy.

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

The dissolution in water of which of the following substances is endothermic?

  1. Hydrochloric acid

  2. Sodium hydroxide

  3. Pure sodium

  4. Ammonium chloride
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

(A) $HCl _{(l)}+H _2O _{(l)}\rightarrow HCl _{(aq)}+$ Heat (exothermic)

(B) $NaOH+H _2O\rightarrow Na^++OH^-+H _2O+$ Heat (exo)
(C) $Na _{(s)}+H _2O\rightarrow NaOH+$ Heat (exo)
(D) $AlCl _3+H _2O\rightarrow Al(OH) _3+3HCl$ (endo)

(D) is endothermic reaction.

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

The decomposition of vegetable into compost is an example of __________ reaction.

  1. exothermic

  2. endothermic

  3. displacement

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

The decomposition of vegetable into compost is an example of  exothermic reaction.

The decomposition of vegetable matter into useful compost is carried out by microbes.These reactions involve break down of bonds.The overall reaction is exothermic.

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

$Si + C \rightarrow$ SiC. This chemical reaction is an example for:

  1. exothermic reaction

  2. endothermic reaction

  3. dissociation reaction

  4. displacement reaction
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$Si + C \rightarrow SiC$.

This chemical reaction is an example of an exothermic reaction as heat is liberated during the reaction. It is also an example of a combination reaction. Two elements combine to form a single compound.

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

To start, every biochemical reaction is:

  1. exergonic

  2. endergonic
  3. both $A$ and $B$

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

Since any chemical reaction requires some energy of activation to start with, so this step is endergonic or since biochemical reaction is also a type of chemical reaction, so its first step is endothermic or endergonic.

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

A solution of 500 ml of 0.2 M KOH and 500 ml of 0.2 M HCl is mixed and stirred; the rise in temperature is $T _1$. The experiment is repeated using 250 ml of each solution, the temperature raised is $T _2$. Which of the following is true :

  1. $T _1=T _2$
  2. $T _1=2T _2$
  3. $T _1=4T _2$
  4. $T _2=9 T _1$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The neutralization reaction between a strong acid (HCl) and a strong base (KOH) is exothermic. The temperature rise depends on the heat released per mole of water formed; since the concentration and molar ratios remain the same in both experiments, the temperature rise T1 and T2 should be identical.

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

The following is (are) endothermic reaction(s) :

  1. Combustion of methane.

  2. Decomposition of water

  3. Dehydrogenation of ethane to ethylene.

  4. Conversion of graphite to diamond.
Reveal answer Fill a bubble to check yourself
B,C,D Correct answer
Explanation

Combustion reaction are exothermic, hydrogenation of alkenes are exothermic and graphite is thermodynamically more stable.

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