Question

Cколько теплоты нужно затратить, чтобы нагреть 2 кг льда, что находится при температуре -25, до кипения? Какой мощности нагреватель нужно взять, что бы сделать это за 100 с?

Answer 1

Дано:
m=2 кг
t1=-25 C
t2=0 C
t3=100 C
t=100 c
c1=2100 Дж/кгС
с2=4200 Дж/кгС
λ1=332 400 Дж/кг
Найти Q,Nдвигателя
Q=Q1+Q2+Q3=c1m(t2-t1)+λ1*m+c2m(t2-t1)
Q1=c1m(t2-t1)
Q2=λ1m
Q3=c2m(t2-t1)
Q=(2100 Дж/кгС*2 кг*(0 С+25 С))+(332 400 Дж/кг*2 кг)+(4200 Дж/кгС*2 кг(100 С-25 С)=1 399 800 Дж.

N=A/t
В данном случае А-тепловая работа,то бишь А=Q,тогда N=Q/t
N=1 399 800 Дж/100 с=13 998 Вт.

Answer 2

Q=c льда*m(t2-t1)+λ*m+c воды*m(t3-t2)
Q=2100Дж/кгС*2кг*(0С-(-25С))+3,4*10⁵Дж/кг*2кг+4200Дж/кгС*2кг*(100С-0С)=1625000Дж
P=A/t
Р=1625000Дж/100с=16250ВТ

Answer 3

Calculation of Heat Required to Heat 2 kg of Ice

To calculate the amount of heat required to heat 2 kg of ice from a temperature of -25°C to its boiling point, we need to consider the heat required for two processes: raising the temperature of the ice to 0°C and then melting the ice at 0°C.

1. Heat required to raise the temperature of the ice to 0°C: - The specific heat capacity of ice is approximately 2.09 J/g°C. - The temperature change is from -25°C to 0°C, which is a change of 25°C. - The mass of the ice is 2 kg, which is equivalent to 2000 g. - Using the formula Q = m * c * ΔT, where Q is the heat energy, m is the mass, c is the specific heat capacity, and ΔT is the temperature change, we can calculate the heat required: Q1 = 2000 g * 2.09 J/g°C * 25°C = 104,500 J

2. Heat required to melt the ice at 0°C: - The heat of fusion for ice is approximately 334 J/g. - The mass of the ice is 2 kg, which is equivalent to 2000 g. - Using the formula Q = m * Hf, where Q is the heat energy, m is the mass, and Hf is the heat of fusion, we can calculate the heat required: Q2 = 2000 g * 334 J/g = 668,000 J

3. Total heat required: - To find the total heat required, we add the heat required for both processes: Total heat = Q1 + Q2 = 104,500 J + 668,000 J = 772,500 J

Therefore, approximately 772,500 J of heat is required to heat 2 kg of ice from -25°C to its boiling point.

Power Required to Heat the Ice in 100 seconds

To calculate the power required to heat the ice in 100 seconds, we need to divide the total heat required by the time taken.

1. Total heat required: From the previous calculation, we found that the total heat required is 772,500 J.

2. Time taken: The time taken is given as 100 seconds.

3. Power required: - Power is defined as the rate at which work is done or energy is transferred. - Using the formula P = Q / t, where P is the power, Q is the heat energy, and t is the time, we can calculate the power required: Power = 772,500 J / 100 s = 7,725 W

Therefore, a power of approximately 7,725 W is required to heat the 2 kg of ice in 100 seconds.

Please note that these calculations are approximate and may vary depending on the specific properties of the ice and the heating process.