Question

Find the change in internal energy in joule when 10g of air is heated from 30 degrees to 40 degrees

Answer 1

Answer:

Given,

Mass of air = 10g

Since 1 g = 1 * kg

So 10 g = 10 * kg

Mass of air =  10 * kg

Given,

Air is heated from 30c to 40c

We know,

0°C + 273.15 = 273.15K  , that is ,

30°C  in Kelvin = 30 + 273.15 = 303 K

40°C  in Kelvin = 40 + 273.15 = 313 K

So ,

Δ T = 313 - 303 K = 10 K

We know

 = 0.172kcal / kg K and

J = 4200J / k.cal

Now,

Change in internal energy    = m *  * Δ T

 =  10 *  * 0.172 * 4.2 * 10³ * 10

= 17.2 * 4.2

= 72.24 J