Question

True or False????

1) The Cp,m of He gas at 10K and 1 atm is larger than 5R/2.

2) ΔH does not depend on temperature.

3) Whether the equilibrium constant of an ideal-gas reaction increases or decreases, as T increases, is determined by the sign of ΔH.

4) Since the concentrations of reactants decreases with time, the rate, r, of a reaction always decreases as time increases.

Need help asap, please write a little explanation/reasoning as to why it is T/or F. Thank you.

Answer 1

1. True. The relation Cp = 5/2R it's accomplished when the pressure and volume is constant, (without depending on temperature), and for a monoatomic gas like He, we know that Cp + Cv = R, so this relationship is correct.

2. False. According to Kirchhoff's Law, it describes the enthalpy of a reaction's variation with temperature changes. In general, enthalpy of any substance increases with temperature, which means both the products and the reactants' enthalpies increase. The overall enthalpy of the reaction will change if the increase in the enthalpy of products and reactants is different.

3. According to The van 't Hoff equation, shows that when the reaction is exothermic (ΔH is negative), then K decreases with increasing temperature, in accordance with Le Chatelier's principle. It permits calculation of the reaction equilibrium constant at temperature T₂ if the reaction constant at T₁ is known and the standard reaction enthalpy can be assumed to be independent of temperature even though each standard enthalpy change is defined at a different temperature. That's why this is False.

4. True.  Reaction rate increases with concentration, as described by the rate law and explained by collision theory. As reactant concentration increases, the frequencyof collision increases.