Question

1. Calculate the kinetic energy of a person whose mass is 59.0 kg and is moving with a velocity of 26.5 m/s. 8 points 2. Define first law of thermodynamics. 4 points 3. How much heat could you obtain from 10.0 g of methane, CHa, assuming you have excess of oxygen. The thermochemical equation is given. CHA (6) + 20€) → CO2(g) + 2 H20 (0); AH = -890.3 kJ 10 points

Answer 1

1.

Kinetic energy has the formula ; K.E = (1/2)m.V 2

mass of the person is given, m = 59 Kg

Velocity of the person is given, V = 26.5 m/s

therefore K.E = (1/2) * 59 * (26.5) 2 = 20716 J = 20.716 KJ

answer : kinetic energy = 20.716 KJ

2.

First Law of Thermodynamics

First law of thermodynamics tells about conservation of energy.

Statement : energy can be neither created nor destroyed but can be converted from one form to another.

It can be also explained as, " in an isolated system, sum of work done by the system and heat transfered from the system is equal to change in internal energy of the system."

3.

Given reaction ;   CH4 (g) + 2 O2 (g) $\rightarrow$ CO2 (g) + 2 H2O (g)    $\Delta$ H = 890.3 KJ

molar mass of CH4 = 16 g/mol

number of moles in 10 g CH4 = 10 / 16 = 0.625 mol

combustion of 1 mole CH4 gives 890.3 KJ

Therefore combustion of 0.625 mole CH4 gives 890.3 * (0.625/1) KJ = 556.4 KJ

Therefore combustion of 10 g of methane produces an heat of 556.4 KJ