Question

Воздух массой 200г. нагревают при постоянном давлении от 40-80○с,в результате чего объём увеличивается на 0,01м3 .насколько при этом изменяется внутренняя энергия воздуха,если его давление равно 150кПа?Удельная теплоёмкость воздуха при постоянном давлении равна 1000Дж,молярная масса воздуха -29○с

Answer 1

P=1,5*10^5=const

T1=313

T2=353

dV=0,01

M=29*10^-3

j=5

m=0,2 
dU=0,5*5*(0,2/29*10^-3)*8.31*40

R=8,31; dT=40, 

A=1.5*10^5*0.01

Q=A+dU

Answer 2

To calculate the change in internal energy of the air when its volume increases at constant pressure, we can use the equation:

ΔU = n * Cp * ΔT

Where: ΔU is the change in internal energy n is the number of moles of air Cp is the molar specific heat capacity at constant pressure ΔT is the change in temperature

First, let's calculate the number of moles of air. We can use the ideal gas law equation:

PV = nRT

Where: P is the pressure V is the volume n is the number of moles R is the ideal gas constant T is the temperature

Given: Pressure (P) = 150 kPa Volume change (ΔV) = 0.01 m^3 Molar mass of air = 29 g/mol

Using the ideal gas law, we can rearrange the equation to solve for the number of moles (n):

n = PV / RT

To calculate the temperature (T), we need to convert the temperature change from Celsius to Kelvin:

ΔT = 80°C - 40°C = 40 K

Now, let's calculate the number of moles of air:

n = (150 kPa * 0.01 m^3) / (8.314 J/(mol·K) * (40 + 273) K)

Now that we have the number of moles, we can calculate the change in internal energy (ΔU) using the molar specific heat capacity at constant pressure (Cp):

Cp = 1000 J/(mol·K)

ΔU = n * Cp * ΔT

Let's calculate the change in internal energy:

ΔU = (n) * (Cp) * (ΔT)

Now, let's substitute the values into the equation and calculate the change in internal energy.