The density of lead is 1.13 ✕ 104 kg/m3 at 20.0°C. Find its density (in kg/m3) at 143°C. (Use α = 29 ✕ 10−6 (°C)−1 for the coefficient of linear expansion. Give your answer to at least four significant figures.)

Respuesta :

Answer:

[tex]{\rho_{143\ ^0C}}=1.118\times 10^4\ kg/m^3}[/tex]

Explanation:

The expression for the volume expansion is:-

[tex]V_2=V_1\times [1+3\times \alpha\times \Delta T][/tex]

Where,

[tex]V_2\ and\ V_1[/tex] are the volume values

[tex]\alpha[/tex] is the coefficient of linear expansion = [tex]29\times 10^{-6}\ (^0C)^{-1}[/tex]

Also,

Density is defined as:-

[tex]\rho=\frac{Mass}{Volume}[/tex]

or,

[tex]Volume=\frac{Mass}{\rho}[/tex]

Applying in the above equation, we get that:-

[tex]\frac{M}{\rho_2}=\frac{M}{\rho_1}\times [1+3\times \alpha\times \Delta T][/tex]

Or,

[tex]{\rho_2}=\frac{\rho_1}{[1+3\times \alpha\times \Delta T]}[/tex]

So, From the question,

[tex]\Delta T=143-20\ ^0C=123\ ^0C[/tex]

[tex]\rho_1=1.13\times 10^4\ kg/m^3[/tex]

Thus,

[tex]{\rho_2}=\frac{1.13\times 10^4\ kg/m^3}{[1+3\times (29\times 10^{-6}\ (^0C)^{-1})\times \Delta (123\ ^0C)]}[/tex]

[tex]{\rho_2}=1.118\times 10^4\ kg/m^3}[/tex]