Question

Molar heat capacity of aluminium is 25 J K-1 mol-1. The heat necessary to raise the temperature of 54 g of aluminium (Atomic mass 27 g mol-1) from 30°C to 50°C is
(a) 1.51 kJ
(6) 0.5 kJ
(c) 1.0 kJ
(d) 2.5 kJ


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Answer 1

Answer:

mark as brainliest.........if understood

Answer 2

Answer: The correct answer is Option c.

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Given mass of aluminium = 54 g

Molar mass of aluminium = 27 g/mol

Putting values in above equation, we get:

$\text{Moles of aluminium}=\frac{54g}{27g/mol}=2mol$

To calculate the amount of heat absorbed, we use the equation:

$Q=nc\Delta T$

where,

Q = heat absorbed = ?

n  = Moles of aluminium = 2 mole

c = specific heat capacity of aluminum = $25J/mol.K$

$\Delta T$ = change in temperature = $(50-30)^oC=20^oC=20K$  (change remains the same)

Putting values in above equation, we get:

$Q=2mol\times 25J/mol.K\times 20K\\\\Q=1000J=1.0kJ$

Conversion factor used:  1 kJ = 1000 J

Hence, the correct answer is Option c.