Question

Calculate the amount of heat needed to boil 144 grams of water beginning from a temperature of 33.2 degrees C. Be sure your answer has a unit symbol and the correct number of significant digits.

Answer 1

- First, it has to be heated from 33.28°C to 100°c and at 100°c it has to be vaporized - For heating purpose, we have to consider specific heat of liquid water. specific heat, s=4.186 g. mass of water, m= 1449 change in temperature = Tf -T; = 100°C - 33.2°C = 66.8°c Amount of heat needed for this = mxsxAT = 1448*4. 186 T x 66.8 € (AT) → Vi = 40,266 J = 40.266 KJ.

To boil water, it has to be vaporized of rooc This can be calculated by taking "Latent heat of vaporization of water. - Latent heat of a vaporization (Lv) of water = 2256 J/g → Amount of heat needed to boil 144g of water at 100°c to boil = m xlv (V) = 1448x2256 I = 324864 J = 324.864 KJ. 9 = 324.864 KJ. total heat needed = q , +% = (40.266 + 324.864) KJ = 365.13 KJ. Answer: 365.130 KJ.