Equilibrium Flashcards
If 1 mol of NaHCO3 is dissolved in 1 L of H2O at 4°C, what amount of NaHCO3 will remain after the solution has reached equilibrium? Ksp for sodium bicarbonate is 0.814 at 4°C.
To solve this question, we have to use the given value of Ksp and set up the equilibrium relationship. The dissolution reaction for NaHCO3 is: NaHCO3 (s) ⇌ HCO3- (aq) + Na+ (aq) We can then write the equilibrium constant equation as: Ksp = [HCO3-][Na+] = 0.814 Pure solids are not included in equilibrium constants (since we cannot change their concentrations). To determine how much of the solid will dissolve, we can set up a hypothetical dissolution reaction. From the balanced reaction, we know that for every x moles of NaHCO3 that dissolve, x moles of each ion product will form. So the final moles of NaHCO3 are 1-x moles, and the moles of product formed are x moles of Na+ and x moles of HCO3-. Now we can use the Ksp to determine how many moles of ions are formed. Ksp = [x][x] = 0.814 Ksp = x2 = 0.814 x= √0.814 = √0.81= 0.9 M x 1 L of solution = 0.9 moles Now we know that the change in each compound is 0.9 moles. The question asked us to solve for the final amount of NaHCO3 (s), which is 1 – 0.9 moles = 0.1 moles.
Removal of heat from a lead-acid battery will lead to a decrease in the concentration of:
PbO2
Pb
H+
PbSO4
H+
Le Chatelier’s principle states that a decrease in the concentration of a product will lead to a decrease in the concentration of reactants. While heat is not measured as a concentration, Equation 1 shows that heat is a product, so removal of heat will cause a decrease in the concentration of reactants. H+ (aq), Pb (s), and PbO2 (s) are all reactants. However, Le Chatelier’s principle does not apply to solids and liquids because their concentrations stay almost constant even if they are added to or removed from the reaction in absolute terms, making choice C correct.
True or False: Le Chatelier’s principle does not apply to solids and liquids because their concentrations stay almost constant even if they are added to or removed from the reaction in absolute terms
True
