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2 answers:
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Answer:
Option b. Sodium chloride.
Explanation:
Consider the dissociation equilibrium of in water:
.
By the Le Chatelier's Principle, increasing the concentration of either product will shift the equilibrium to the left. Some that was initially dissolved will precipitate out of the solution. This effect is called the common-ion effect.
For this solution, the products of dissociation are
ions, and
ions.
Adding either to the solution will trigger the common-ion effect and reduce the solubility of .
In the two choices,
- Sodium chloride
will add
and
- Sodium fluoride
will add
ions to the solution.
contains
ions. It is capable of triggering the common-ion effect. However
contains neither
ions nor
ions. It will not trigger the common-ion effect.
Answer:- Heat lost by the metal is 279.45 cal.
Solution:- This type of problems are solved by using the concept, heat given = - heat taken
Metal temperature is decreasing from 45.00 degree C to 11.08 degree C. It means the heat is lost by the metal and this heat lost by metal is gained by water and the calorimeter to raise their temperature.
the equation we use is, .
where, q is the heat energy, m is mass, c is specific heat and is change in temperature.
Combined mass of calorimeter and water is 250.0 g and the specific heat is .
for calorimeter and water (combined) = 11.08 - 10.00 = 1.08 degree C
for metal = 11.08 - 45.00 = -33.92 degree C
let's plug in the values in the above equation and calculate heat gained by combined system.
q=250.0g*\frac{1.035cal}{g.^0C}*1.08^0C
q = 279.45 cal
So, the heat lost by the metal is 279.45 cal.