A40.2 g sample of a metal heated to 99.3â°c is placed into a calorimeter containing 120 g of water at 21.8â°c. the final temperature of the water is 24.5â°c. which of the following might be the metal that was used?
a) aluminum (c=0.89j/gâ°c)
b) iron (c=0.45j/gâ°c)
c) copper (0.20j/gâ°c)
d) lead (c=0.14j/gâ°c)

B) Iron (c=0.45 J/g°C)

Explanation:

Given that:-

Heat gain by water = Heat lost by metal

Thus,  

Where, negative sign signifies heat loss

Or,  

For water:

Mass = 120 g

Initial temperature = 21.8 °C

Final temperature = 24.5 °C

Specific heat of water = 4.184 J/g°C

For metal:

Mass = 40.2 g

Initial temperature = 99.3 °C

Final temperature = 24.5 °C

Specific heat of metal = ?

So,  

This value corresponds to iron. Thus answer is B.

the dissociation of nickel hydroxide is follows:

the concentration of hydroxide ion is

the equilibrium constant value of nickel hydroxide is = 6.1 * 10^-^1^6 and thus equilibrium equation can be written as:

thus, concentration of ni is 0.23 * 10^-^4 mol /l