The number of sulfate ions that are in 100 ml of a solution of 0.0020 M Fe2(SO4)3 is 6 x10 ^-4 moles
calculation
find the moles of Fe2(SO4)3 that dissociated
moles = molarity x volume in liters
volume in liters = 100/1000 = 0.1 liters
molarity =0.002 M
moles = 0.002 x0.1 =2 x10 ^-4 moles
write the equation for dissociation
Fe2(SO4)3 = 2fe^3+ + 3 SO4^2-
by use of mole ratio between Fe2(SO4)3 to SO4^2- which is 1:3 therefore the moles of SO4^2- is
= 0.0002 x3 = 6 x10 ^-4 moles
Answer:
½N 2(g) + O 2(g) + 8.1 kcal → NO 2(g)
½N 2(g) + ½O 2(g) → NO(g), ΔH = +21.6 kcal/mole
NH 3(g) → ½N 2(g) + 3/2H 2(g), ΔH = +11.0 kcal/mole
General Formulas and Concepts:
<u>Thermochemistry</u>
- Endothermic vs Exothermic
- Enthalpy
Explanation:
An endothermic reaction would have heat or energy gained in the final stage of the reaction.
This means that our enthalpy would be positive and heat/energy would be added as a reactant.
Out of all the answer choices, we see that only these have heat/energy added in the reactant side or the enthalpy being positive:
½N 2(g) + O 2(g) + 8.1 kcal → NO 2(g)
½N 2(g) + ½O 2(g) → NO(g), ΔH = +21.6 kcal/mole
NH 3(g) → ½N 2(g) + 3/2H 2(g), ΔH = +11.0 kcal/mole
Topic: AP Chemistry
Unit: Thermochemistry