Question

Сколько спирта надо сжечь, чтобы изменить температуру воды массой 2 кг на 36С, если вся теплота, выделенная спиртом, пойдет на нагревание воды? Удельная теплота сгорания спирта 26*10 в шестой степени (Дж/кг), удельная теплоемкость воды 4200 Дж/кг*С(цельсию) Ответ выразите в килограммах.

Answer 1

Calculation of the Amount of Alcohol Needed to Change the Temperature of Water

To calculate the amount of alcohol needed to change the temperature of water, we can use the principle of conservation of energy. The heat released by burning alcohol will be used to heat the water.

The formula to calculate the heat released by burning alcohol is:

Q = m × c × ΔT

Where: - Q is the heat released (in Joules) - m is the mass of alcohol burned (in kilograms) - c is the specific heat capacity of alcohol (in J/kg·°C) - ΔT is the change in temperature of the alcohol (in °C)

In this case, we want to find the mass of alcohol needed to change the temperature of 2 kg of water from 36°C to a higher temperature. The specific heat capacity of water is 4200 J/kg·°C.

Let's calculate the heat required to raise the temperature of the water:

Q_water = m_water × c_water × ΔT_water

Where: - Q_water is the heat required to raise the temperature of water (in Joules) - m_water is the mass of water (2 kg) - c_water is the specific heat capacity of water (4200 J/kg·°C) - ΔT_water is the change in temperature of water (36°C)

Now, let's calculate the heat released by burning alcohol:

Q_alcohol = m_alcohol × c_alcohol × ΔT_alcohol

Where: - Q_alcohol is the heat released by burning alcohol (in Joules) - m_alcohol is the mass of alcohol burned (unknown) - c_alcohol is the specific heat capacity of alcohol (26 × 10^6 J/kg) - ΔT_alcohol is the change in temperature of alcohol (unknown)

Since the heat released by burning alcohol is equal to the heat required to raise the temperature of water, we can set the two equations equal to each other:

Q_alcohol = Q_water

m_alcohol × c_alcohol × ΔT_alcohol = m_water × c_water × ΔT_water

Substituting the known values:

m_alcohol × (26 × 10^6 J/kg) × ΔT_alcohol = (2 kg) × (4200 J/kg·°C) × (36°C)

Simplifying the equation:

m_alcohol = (2 kg) × (4200 J/kg·°C) × (36°C) / (26 × 10^6 J/kg) × ΔT_alcohol

To find the mass of alcohol needed, we need to know the change in temperature of alcohol (ΔT_alcohol). Unfortunately, the change in temperature of alcohol is not provided in the question. Therefore, we cannot calculate the exact mass of alcohol needed without this information.

Please provide the change in temperature of alcohol (ΔT_alcohol) so that we can calculate the mass of alcohol needed.