CHEM 163 EXAM 4 SI REVIEW

1. Whats a solute?

The part that get dissolved

2. Whats a solvent?

The part thatdoes the dissolving

3. Whats a solution?

homogeneous mixture of solute and solvent

4. Example of liquid/solid, liquid/liquid, solid/solid solutions

liquid/solid- sugar and water. Liquid/liquid -ethanol in water, solid/solid – alloy.

5. Name the 3 steps of solution formation and if they require energy or if energy is

released.

1. Solute separation – solute molecules overcome the attractive forces and dissociate

(energy is absorbed)

2. Solvent separation – solvent molecules make space for solute (energy is

absorbed)

3. Solvation – new interaction are formed between solute and solvent (energy is

released).

6. For example, if for a given solution, solute separation needs 100J of energy, solvent

separation takes 50J and solvation takes -250J, will the solute dissolve spontaneously?

7. Out of the following, which one is more likely to be dissolved in water at room

temperature? CH3Cl, CH3OH or CCl4?

polar solvent dissolves polar solutes, and non polar solvents dissole non polar solutes

8. Entropy is the measure of _______________. When a solution is formed, entropy

______________ (increases/decreases).

9. Solubility depends on 3 things. Can you name them.

10. What is the formula for calculating concentration of a solution?

11. What is the concentration of a solution in which I have mixed 2moles of NaCl in 2500mL

of water?

12. If the molar mass of NaCl is 58.5g/mol, how many grams of NaCl is there in 300mL of 2M

NaCl solution?

13. What is the formula for solution dilutions?

14. How many mL of stock solution do I need to dilute 2M stock to 1M solution of 3000mL

final volume?

15. What would be my final concentration if I add 200mL of 3M solution to 1L of water?

16. What is the formula for percent concentration by mass? Percent composition by

volume? Percent mass/volume?

17. How many g of NaCl is present in 200mL of 10% by mass solution?

18. How many mL of “pure” Ethanol did Dhaval hypothetically consumed if he drank 355mL

of beer (5% by volume) last night.

19. I mix 0.755M Ba(NO3)2 and 1.250M Ca(OH)2 in hope of trying to make 5g of precipitate.

How much volume of each do I need? (molar mass of Ba(OH)2 is 171.34g/mol and molar

mass of Ca(NO3)2 = 164g/mol

20. In order to find the concentration of an HBr solution, I titrate it against 0.1M NaOH

solution. I need 43mL of NaOH to neutralize all the 10mL HBr solution. What is the

concentration of my unknown HBr?

21. What are colligative properties?

don’t depend on property of the solute molecule, but the number of solute

molecules.

22. What are the 3 colligative properties you studied?

boiling – elevation

freezing point depression

vapor pressure decreases.

23. Compare 1 mol of NaOH, NH4Cl, Ca(OH)2, C6H12O6. Which of these will cause the most

change in the colligative property of water when dissolved?

24. Compare 1mole of H2SO4, Ca(NO3)2, (NH4)2CO3, which one of these will cause most

change in the colligative property of water when dissolved?

25. Energy _______________ (absorbed/released) when bonds are broken. Energy is

____________ (absorbed/released) when bond is formed.

26. Whats an exothermic reaction? Whats an endothermic reaction?

exothermic: heat is given out, endothermic: heat is absorbed.

27. Whats activation energy? Whats transition state?

activation: energy required for reaction to start. Transition state: bonds are breaking

and forming/intermediate state.

28. How do you calculate the ΔE of reaction? What does the sign of this value tell you?

29. For a particular reaction, the reactants are at 30J while the products are at 60J and the

transition state is at 100J. Calculate the ΔE of reaction and the Eactivation. Is this

reaction endothermic or exothermic?

30. How does temperature affect the rate of reaction?

31. What does a catalyst do and how does that affect a rate of reaction?

32. In the following rate reaction, name each variable

33. If k is large, what can you say about the rate of the reaction?

34. How does k and Eactivation relate?

35. What is the order of the reaction given in Q32?

36. Calculate the rate constant for the following rate equations

37.