Question

скільки теплоти виділитися при охолодженні 3 кг води від 20°-ти до 5° 1)охолоджуємо до 0) 2)крестилізуємо воду 3)охолоджуємо лід до 0 до -5​

Answer 1

Calculating Heat Release When Cooling Water

To calculate the amount of heat released when cooling 3 kg of water from 20°C to 5°C, we can use the formula:

Q = mcΔT

Where: - Q = heat released or absorbed - m = mass of the substance (in this case, water) in kg - c = specific heat capacity of the substance - ΔT = change in temperature in °C

Let's calculate the heat released in each scenario you've mentioned.

1) Cooling to 0°C

First, let's calculate the heat released when cooling 3 kg of water from 20°C to 0°C.

The specific heat capacity of water is approximately 4.18 J/g°C or 4186 J/kg°C.

Using the formula Q = mcΔT: - m = 3 kg - c = 4186 J/kg°C - ΔT = 20°C - 0°C = 20°C

Calculating Q: Q = 3 kg * 4186 J/kg°C * 20°C = 250,320 J

So, when cooling 3 kg of water from 20°C to 0°C, approximately 250,320 Joules of heat will be released [[1]].

2) Crystallizing Water

When water crystallizes into ice at 0°C, it releases a specific amount of heat known as the heat of fusion. The heat of fusion for water is approximately 334,000 J/kg.

So, when 3 kg of water crystallizes into ice at 0°C, the heat released can be calculated as: Q = m * heat of fusion Q = 3 kg * 334,000 J/kg = 1,002,000 J

Therefore, when 3 kg of water crystallizes into ice at 0°C, approximately 1,002,000 Joules of heat will be released [[2]].

3) Cooling Ice from 0°C to -5°C

Finally, let's calculate the heat released when cooling 3 kg of ice from 0°C to -5°C.

The specific heat capacity of ice is approximately 2.09 J/g°C or 2090 J/kg°C.

Using the formula Q = mcΔT: - m = 3 kg - c = 2090 J/kg°C - ΔT = 0°C - (-5°C) = 5°C

Calculating Q: Q = 3 kg * 2090 J/kg°C * 5°C = 31,350 J

So, when cooling 3 kg of ice from 0°C to -5°C, approximately 31,350 Joules of heat will be released [[3]].

In summary, the total heat released in the three scenarios is: - Cooling to 0°C: 250,320 J - Crystallizing water: 1,002,000 J - Cooling ice to -5°C: 31,350 J