Asample of naoh(s) was added to water in a calorimeter. the temperature was monitored as the naoh dissolved to give the data below. determine the heat released during the solution process. (assume the solution specific heat is 4.18 j•g–1•k–1)

mass of water 100.00 g
mass of naoh(s) 10.00 g
initial temperature of water 24.0 °c
final temperature of solution 48.2 °c

(a) 1.01 * 103joules
(b) 2.66 * 103joules
(c) 1.01 * 104joules
(d) 1.11* 104joules

(D) 1.11 × 10⁴ J

Explanation:

According to the law of conservation of energy, the sum of the heat released by the solution of NaOH and the heat absorbed by the aqueous dissolution is zero.

Qsol(NaOH) + Qaq,dis = 0

Qsol(NaOH) =  - Qaq,dis [1]

The heat absorbed by the aqueous dissolution can be calculated using the following expression.

Qaq,dis = c × m × ΔT

where,

c: specific heat of the solution (4.18 J.g⁻¹.K⁻¹ = 4.18 J.g⁻¹.°C⁻¹)

m: mass of the aqueous dissolution (100.00 g + 10.00 g = 110.00 g)

ΔT: change in the temperature (48.2°C - 24.0°C = 24.2°C)

Qaq,dis = 4.18 J.g⁻¹.°C⁻¹ × 110.00 g × 24.2°C = 1.11 × 10⁴ J

From [1],

Qsol(NaOH) = -1.11 × 10⁴ J

The amount of heat released during the solution process is 1.11 × 10⁴ J.

h let me think

"hydrogen bonding is the attraction of h atoms in the water molecule (slight + charge) to o atoms in a neighboring water molecule (slight - charge); it is a weak interatomic force. but it is still strong enough to the water molecules "stick" together."