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3 months ago

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A 25.0-g sample of ice at -6.5oC is removed from the freezer and allowed to warm until it melts. Given the data below, select al

l the options that correctly reflect the calculations needed to determine the total heat change for this process.
Melting point at 1 atm = 0,0°C; -2.09 J/g.°C; Cloud -4.21J/g °C, AH -6,02 kJ/mol
Check all that apply.

A. q for the temperature change from -6,5°C to 0.0°C is glven by 25.0 x 6.02 = 151 kJ
B. q for the phase change is given by 1.39 x 6.02 = 8.37 kJ
C. There are 3 separate heat change stages in this process.
D. The total heat change for the process is equal to +8.71 kJ
E. The total heat change for the process is equal to +350 kJ

1 answer:

KiRa [2.9K]3 months ago

7 0

Answer:

B, D

Explanation:

We need to recognize that the ice will rise in temperature from -6.5 ºC to 0 ºC for it to change into water.

Let's define q₁ as the heat needed to warm the ice to 0ºC, and q₂ as the heat for the transition from solid to liquid.

The calculation for q₁ is as follows:

q₁ = s x m x ΔT, where s represents the specific heat of ice (2.09 J/gºC), m is the mass, and ΔT is the temperature difference.

For q₂, the enthalpy of fusion is computed as:

q₂ = C x ΔT

with C indicating the specific heat for the phase transition, denoted as AH in kJ/mol.

All necessary data for computing q₁, q₂, and the total heat change (q₁ + q₂) is provided.

q₁ = 25.0 g x (2.09 J/gºC) x (0 - (-6.5 ºC))

q₁ = 339.6 J = 0.339 kJ

q₂ = (25 g/18 g/mol) x 6.02 kJ/mol = 1.39 x 6.02 kJ = 8.36 kJ

Combining these values gives us qtotal = 0.339 kJ + 8.36 kJ = 8.70 kJ.

Now we can answer the question:

(a) False, AH refers to the heat capacity during melting.

(b) True, as we concluded earlier.

(c) False, there’s only one phase transition from solid (ice) to liquid.

(d) True based on our calculations above.

(e) False, according to our findings.

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