Answer to Question #55532 in General Chemistry for Aleshia

Question

1. A sample of iron absorbs 81.0 J of heat, upon which the temperature of the sample increases
from 17.9 °C to 32.5 °C. If the specific heat capacity of iron is 0.450 J/gK, what is the mass
(in grams) of the sample?
2. Consider the following reaction. (Molar mass of CH3OH = 32.04186 g/mol)
2 CH3OH(g) 2 CH4(g) + O2(g) ΔH = +252 kJ
a) Is this reaction exothermic or endothermic?
b) Calculate the amount of heat transferred when 24.0g of CH3OH(g) is decomposed
by this reaction at constant pressure.
c) For a given sample of CH3OH(g), the enthalpy change during the reaction is 82.1 kJ.
How many grams of methane gas are produced?
d) How many kj of heat are released when 35.8 g of CH4(g) reacts completely
with O2(g) to form CH3OH(g) at constant pressure?
3. The ΔE of a system that releases 10.4 J of heat and does 8.7 J of work on the surroundings is
________ J.