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Published byMelissa Neal Modified over 8 years ago
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Start with Part F Acid may not be strong enough to finish the reaction during the allowed period
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Place small portion of CuSO 4 * 5H 2 O crystals in dry test tube Use test tube holder to heat with bunsen burner Note color change and observe the inside surface at the top of the test tube
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Add NaHCO 3 (baking soda) into 250mL erlenmeyer flask – covering the bottom of the flask Support flask on ring stand with wire gauze Hold a flaming splint in the mouth of the flask, record how long it burns Heat the flask strongly with burner until moisture is observed Hold a flaming splint in the mouth of the flask Record how long it burns
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Put 20 drops of AgNO 3 sol’n in a test tube Add small piece of copper wire Allow few minutes for the reaction Record your observation
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Put 20 drops of HCl sol’n in a test tube Add small piece of magnesium wire Record your observation
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Put 20 drops of DI water in a test tube Add small piece of calcium metal Record your observation
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Put 10 drops of AgNO 3, Cu(NO 3 ) 2, and Al(NO 3 ) 3 sol’ns into separate test tubes (#1-3) Add few drops of K 2 CO 3 sol’n to all 3 test tubes Observe reactions Record observations
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Put 10 drops of AgNO 3, Cu(NO 3 ) 2, and Al(NO 3 ) 3 sol’ns into separate test tubes (#4-6) Add few drops of Na 3 PO 4 sol’n to all 3 test tubes Observe reactions Record observations
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Phenolphthalein is an acid-base indicator that is colorless in acidic and neutral sol’ns and pink in basic sol’ns When you are adding base, make sure to make the pink as faint as possible!! You have added enough base if the sol’n stays faint pink for 30 seconds
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Put 10 drops of HNO 3 (aq), H 2 SO 4 (aq), and H 3 PO 4 (aq) into separate test tubes (#1-3) Add one drop of phenolphthalein to each test tube Add drops of dilute NaOH sol’n into test tube #1 until permanent color change is observed Repeat for test tubes 2 and 3 Record the number of drops of base it takes to neutralize each acid
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Note HNO 3 (aq) monoprotic – releases 1 H + H 2 SO 4 (aq) diprotic – releases 2 H + H 3 PO 4 (aq) triprotic – releases 3 H + Therefore, it should take twice as much base to neutralize sulfuric acid than it does nitric acid It should also take three times as much base to neutralize phosphoric acid as it does nitric acid **Only if they are the same concentration**
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Obtain a post-1982 penny Record the mint date Use metal shears to cut the coin (figure 1) to ensure rapid/complete rxn with sulfuric acid Accurately weigh the penny on the balance, record its mass Drop penny into 100mL beaker Add ~20mL of dilute sulfuric acid
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The rxn requires ~3 hrs for the Zn in the coin to completely react If the acid contacts your skin, wash immediately with water When the coin stops producing gas bubbles, discard the sulfuric acid into the sink Was coin with DI water, discard the wash sol’n Rinse the coin with acetone, and discard sol’n When the coin appears dry, weigh the copper shell, record the mass Calculate the percentages of copper and zinc
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The rxn will most likely not be complete before you leave lab. Therefore, you can come in around 4 on Wednesday to weigh your penny and finish the simple calculations for the lab. The lab and post lab questions will be due at the beginning of next lab period.
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Make sure that you balance the rxn’s when you are writing the products Makes sure to write the phases
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Use the reactions you just determined to answer #1 For #2 use the activity series from your book For #3 use the solubility rules from your book For #4 make sure to balance and write the phases for each reaction #5 is not optional
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