Question

Яку кількість теплоти слід затратити, щоб розплавити 5 кг льоду взятого при температурі -20°С?

Answer 1

Дано:
m=5 кг
t1=-20°C
t плав.=0°С
c=2100 Дж/кг×°С
лямбда=3,4×10^5 Дж/кг
Q=?
Решение.
Q=Q1+Q2
Q1=cm∆t
Q2=лямбда×m
Q1=2100 Дж/кг×°С ×5 кг × 20°С=210000 Дж
Q2=3,4×10^5 Дж/кг × 5 кг=17×10^5 Дж
Q=210000 Дж + 17×10^5 Дж=191×10^4 Дж
Ответ: 1910 кДж

Answer 2

Calculation of Heat Required to Melt Ice

To calculate the amount of heat required to melt ice, we can use the formula:

Q = m * L

Where: - Q is the heat energy required (in joules) - m is the mass of the ice (in kilograms) - L is the latent heat of fusion for ice (in joules per kilogram)

In this case, we are given that the mass of the ice is 5 kg and the ice is at a temperature of -20°C. We need to find the amount of heat required to melt this ice.

Finding the Latent Heat of Fusion for Ice

The latent heat of fusion for ice is the amount of heat energy required to change a substance from a solid to a liquid state at its melting point. The latent heat of fusion for ice is approximately 334,000 joules per kilogram (J/kg).

Calculation

Using the formula mentioned above, we can calculate the amount of heat required to melt the ice:

Q = m * L

Q = 5 kg * 334,000 J/kg

Q = 1,670,000 joules

Therefore, approximately 1,670,000 joules of heat energy is required to melt 5 kg of ice taken at a temperature of -20°C.

Please note that this calculation assumes that the ice is pure and that no heat is lost to the surroundings during the melting process.

I hope this helps! Let me know if you have any further questions.