Question

ПОМОГИТЕ ПОЖАЛУЙСТА СРОЧНО какое количество свинца можно расплавить затратив 126 кДж тепла. Начальная температура свинца 27 градусов, температура плавления 327 градусов

Answer 1

Из таблицы берем удельную теплоемкость и удельную теплоту плавления свинца: с=140 Дж/кг гр.С
лямбда =0,25*10^5Дж/кг
Q1 для нагревания=cm(t2-t1)
Q2 для плавления=лямбда*m
Q=Q1+Q2=m(c(t2-t1)+лямбда)
m=126000/(140*(327-27)+0,25*10^5)Дж.
подсчитай сама.

Answer 2

Calculation of the Amount of Lead that can be Melted

To calculate the amount of lead that can be melted using 126 kJ of heat, we need to consider the specific heat capacity of lead and the temperature change involved.

The specific heat capacity of lead is approximately 0.13 J/g°C. This means that it takes 0.13 Joules of heat to raise the temperature of 1 gram of lead by 1 degree Celsius.

Given that the initial temperature of the lead is 27 degrees Celsius and the melting point of lead is 327 degrees Celsius, we can calculate the temperature change as follows:

Temperature change = Melting point - Initial temperature = 327°C - 27°C = 300°C

To calculate the amount of heat required to raise the temperature of the lead by 300 degrees Celsius, we can use the formula:

Heat = Mass × Specific heat capacity × Temperature change

We can rearrange the formula to solve for the mass:

Mass = Heat / (Specific heat capacity × Temperature change)

Substituting the given values:

Mass = 126 kJ / (0.13 J/g°C × 300°C)

Converting kJ to J:

Mass = 126,000 J / (0.13 J/g°C × 300°C)

Calculating the mass:

Mass ≈ 3230.77 grams

Therefore, approximately 3230.77 grams (or 3.23 kilograms) of lead can be melted using 126 kJ of heat, given the initial temperature of 27 degrees Celsius and the melting point of 327 degrees Celsius.

Please note that this calculation assumes ideal conditions and does not account for any heat losses or other factors that may affect the actual amount of lead that can be melted.