Student Review Packet Answer Key 1. Label each of the following substances as either acid or base. a. NaOH base b. H 2 SO 4 acid c. H 3 PO 3 acid d. KOH base e. NH 3 base f. HCl acid g. LiOH base h. C 2 H 5 OH base i. HNO 3 acid j. HC 2 H 3 O 2 acid 2. Describe acids and bases as defined by the following scientists: Arrhenius: An Arrhenius acid is a hydrogencontaining compound that ionizes to yield hydrogen ions in aqueous solution. An Arrhenius base is a compound that ionizes to yield hydroxide ions in aqueous solutions. BrønstedLowry: A BrønstedLowry acid is a hydrogenion donor. A BrønstedLowry base is a hydrogenion acceptor. Lewis: A Lewis acid is a substance that can accept a pair of electrons to form a covalent bond. A Lewis base is a substance that can donate a pair of electrons to form a covalent bond. 3. Label the BrønstedLowry acid, BrønstedLowry base, conjugate acid, and conjugate base in the following examples: + a. NH 3 + H 2 O NH 4 + OH base acid conjugate conjugate acid base b. HC 2 H 3 O 2 + H 2 O C 2 H 3 O 2 + H 3 O + c. HCl + H 2 O Cl + H 3 O + d. H 2 O + NaOH OH + + NaOH 2 Page 113
4. Describe the observable properties of acids and bases: acids: tastes sour electrolytes turns litmus paper red will react with a base to produce a salt and water will react with active metals to produce hydrogen gas causes indicators to change color bases: tastes bitter feels slippery electrolytes turns litmus paper blue will react with an acid to produce salt and water cause indicators to change color 5. Indicators use different colors to show what ph range an acid or base falls in. Using the following table of indicators, answer the following questions. INDICATORS Indicator ph range Thymol Blue 1 2.5 Methyl Red 4 6 Bromothymol Blue 6 7.5 Phenolphthalein 8 10 a. Which indicator would you use to measure the ph of hydrochloric acid (strongly acidic)? Thymol blue because HCl is a strong acid. b. Could you use methyl red to indicate the ph of bleach? (Remember, cleaners are typically bases) Why or why not? No, because bleach is a base and methyl red turns color between a ph of 46 which is acidic. 6. Find the ph of the following concentrations. a. [H + ] =.01 M ph = 2 b. [H + ] = 1 x 10 8 M ph = 8 c. [H + ] = 3.8 x 10 4 M ph = 3.4 d. [H + ] = 7.8 x 10 12 M ph = 11 e. [OH ] =.0001 M ph = 10 f. [OH ] = 1 x 10 13 M ph = 1 g. [OH ] = 6.9 x 10 2 M ph = 13 Page 114
h. [OH ] = 2.4 x 10 8 M ph = 6.4 7. Find the poh of the following concentrations. a. [OH ] =.001 M poh = 3 b. [OH ] = 1 x 10 3 M poh = 3 c. [OH ] = 4.7 x 10 6 M poh = 5.3 d. [OH ] = 6.9 x 10 10 M poh = 9.1 e. [H + ] =.1 M poh = 13, technically 1Ō f. [H + ] = 1 x 10 1 M poh = 13, technically 1Ō 8. Label the boxes under the ph scale as slightly basic, slightly acidic, very basic, and very acidic. ph Scale 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 very acidic slightly acidic slightly basic very basic 9. Complete and balance the equations for the following neutralization reactions. a. HCl + NaOH NaCl + H 2 O b. H 2 SO 4 + Ca (OH) 2 CaSO 4 + 2H 2 O c. HC 2 H 3 O 2 + KOH KC 2 H 3 O 2 + H 2 O d. 2HNO 3 + Ba (OH) 2 Ba (NO 3 ) 2 + 2H 2 O e. H 3 PO 4 + 3LiOH Li 3 PO 4 + 3H 2 O 10. Carry out the following neutralization calculations using the following formula: a[a]v A = b[b]v B Page 115
a. How much 3.00 M HF is needed to neutralize 0.750 L of 0.5 M NaOH? (1)(3.00 M)V A = (1)(0.5 M)(0.750 L) V A = 0.125 L =.1L b. How much 6.00 M NH 3 is needed to neutralize 2.25 L of 3.00 M H 2 SO 4? (2)(3.00M)(2.25 L) = (1)(6.00 M)V B V B = 2.25 L c. How much 9.00 M H 2 SO 4 is needed to neutralize 985 ml of 2.85 M Ca(OH) 2? (2 )(9.00M)(V A ) = (2)(2.85 M)(0.985 L) V A = 312 ml 11. Define buffer: a solution that resists change in ph when acids/bases are added to it Circle the correct answer. 12. Recall that bases turn blue litmus paper (blue) and turn red litmus paper (blue). 13. The (solvent) is the part of the solution that you have the most of. Water is typically the (solvent) unless otherwise stated. 14. Imagine that you are in charge of an environmental cleanup crew. You are to neutralize a KOH spill. You select (HBr) to neutralize the spill. 15. A solution is (homogeneous). 16. If you have a solution of salt water, how can you make more salt dissolve into the water? a. add more solvent (more water) b. agitate (stir) c. increase the temperature d. increase the surface area (crush the salt into finer crystals) 17. What does a solubility curve tell you? The amount of solute that will dissolve in 100 g (100 ml) of water at a specific temperature 18. At 30 C, how many grams of KClO 3 are needed to make a saturated solution with 100g of water? ~ 10 grams 19. 50 C and 60g of KNO 3 per 100g of water, is the solution saturated, supersaturated, or unsaturated? Unsaturated 20. At 100 C and 110g of NaNO 3 per 100g of water, is the solution saturated, supersaturated, or unsaturated? Unsaturated 21. Which chemical is most soluble at 30 C?KI 22. Which chemical is least soluble at 50 C? Ce 2 (SO 4 ) 3
23. Conjugate Pairs: Identify the conjugate base of the following acids. a. H 2 SO 4 HSO 4 b. HSO 3 2 SO 3 c. H 3 O + H 2 O d. H 2 O OH