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Thermochemistry
Thermochemistry
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1)
Chemical reaction that absorbs heat from the surroundings is said to be __________ and has a __________∆H at constant pressure.
exothermic, positive
Endothermic, negative
Endothermic, positive
Exothermic, neutral
2)
While performing the calorimetry experiment in the lab, a student wishes to determine the water equivalent of calorimeter. He pours 50 ml of hot water at 55 °C into the calorimeter containing 50 ml of water at 27 °C. After mixing the two, he got the final temperature as 38 °C. What is the value of water equivalent of calorimeter?
16.67 g
166.7 g
11.11 g
12.3 g
3)
Which one of the following devices is used to determine the enthalpy of dissolution of a given salt?
Calorimeter
Viscometer
Potentiometer
Hygrometer
4)
For a given chemical reaction, ∆H is negative. This means that the reaction is _______________.
Enothermic
Equithermic
Exothermic
Adiabatic process
5)
Which statement is true?
Heat is evolved when an endothermic reaction occurs.
An endothermic reaction absorbs heat from the surroundings.
The reaction vessel becomes hot when an endothermic reaction occurs.
An endothermic reaction is characterized by a negative value of ∆H.
6)
The reaction CaCl₂.6H₂O (s)+400H₂O (l)→CaCl₂.6H₂O (400H₂O); ∆H=+18.83 kJ is ________________and heat is _______________by the reaction.
Endothermic, released
Exothermic, absorbed
Endothermic, absorbed
Exothermic, released
7)
Which one of the following is incorrect?
An endothermic reaction is characterized by the positive value of ∆H.
Heat is evolved when an exothermic reaction occurs.
The reaction vessel becomes hot when an exothermic reaction occurs.
An exothermic reaction is characterized by the positive value of ∆H.
8)
When NH₄Cl (s) is added to water, the resulting solution feels cool to touch. Which best describes this observation?
Heat is released as NH₄Cl (s) dissolves.
It is an exothermic reaction.
Heat is absorbed as NH₄Cl (s) dissolves.
The enthalpy of this reaction is negative.
9)
The reaction CaCl₂ (s) + 400H₂O (l) → CaCl₂ (400H₂O); ∆H = -78.60 kJ is _________________ and heat is ______________ by the reaction.
Exothermic, absorbed
Endothermic, absorbed
Endothermic, released
Exothermic, released
10)
Which one of the following is the correct equation for calculating the enthalpy of dissolution of a salt?