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Chemistry 2210A/B Study Guide - Final Guide: Chromate And Dichromate, Titration, Biochemical Oxygen Demand

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purpleturtle147

12 Dec 2016

School

Western University

Department

Course

Chemistry 2210A/B

Professor

Keith Griffiths

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Document Summary

Acid-base and solubility reactions: control concentrations of dissolved inorganic ions, ph mainly controlled by dissolution of atmospheric co2. Oxidation-reduction (redox) reactions: controls concentrations of organic content in water. Parts per blank is the ratio of mass of solute to the mass of the solution. Solubility of gases and vocs: volatile substances that are dissolved in water can eventually evaporate, substances present in air can dissolve in water. When equilibrium is established, henry"s law is used to determine concentration of substance in water, or partial pressure in air. The main oxidizing agent in natural waters is dissolved molecular o2 gas. Each o atom is reduced from 0 oxidation to -2 oxidation,in h2o or oh-. Sum of oxidation numbers = net charge on formula. Group 1, 2 metals = +1, +2; al is +3. The electrons needed for this process are usually acquired from dissolved or suspended organic matter, producing the overall reaction:

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Related Questions

Iâve attached the lab procedures

Could I get some help with the questions please

Weigh boat is 2.20g

Weigh boat + copper is 2.43g

D) Hedung &f thÃ© precipitate in water decomposes the O)2 into CuO, a black solid (Rxn 3). Sulfuric acid is then added to dissolve the copper oxide, forming a light blue solution of Cu(l) ions (Rxn 4). Finally, zinc metal participates a redox reaction with both the copper ions (Rxn 5a) and the excess sulfuric acid (Rxn 5b) to form solid copper metal and evolve hydrogen gas. Using the initial mass copper and the mass of recovered copper after Rxn 5 is complete, the percent recovered fronm this cycle of copper reactions can be calculated using the equation: % Recovered (Final Mass of Copper/initial Mass of Copper)x100 This experiment is based on the manuscript: https:/www.apsu.edufiles/chemistry/COPPER CYCLE $10.pdf Aithough it doesn't show exactly what you will be doing in the lab today, the following video will give you a general idea of what to expect from this lab https://www.youtube.com/watch?v tyne4AFOVY ur Dissolution of Copper Preparation of Copper (Il) nitrate Obtain a sample of copper wire or turnings that weighs between 0.25 to 0.35 grams and place in a 250 mL beaker. Record the actual mass of copper used in your notebook 2. Obtain 4.0 ml of concentrated nitric acid from your instructor and IN THE FUME copper. Remember you need special gloves for this HOOD add it drop wise to the 3. Heat the beaker gently-but NOT to boiling-under the hood using a hot plate until the copper has completely dissolved and no orange gas is being released. If the liquid evaporates ask your instructor to add additional 2 mililiters of nitric acid into your sample and lower the temperature. BE PATIENCE as this is the slowest step of this series of reactions 4. After the copper is completely dissolved slowly add 15.0 mL of distilled water to the beaker and swirl. After adding water, the solution is safe to handle without special gloves, but you still must use regular nitrile gloves. You should see a blue solution that contains copper (I) nitrate. Preparation of Copper (II) Hydroxide 5. Place about 5 mL of 4 M NaOH in a small disposable test tube. Add the NaOH with a dropper to the solution containing the dissolved copper ions until a precipitate remains in the solution. What color is the new precipitate? Write it in your notebook) 6. Once the copper hydroxide has formed allow it to settle. 43

WHICH OF THE FOLLOWING IS NOT AN ARRHENIUS BASE? KOH NH3 LiOH Sr(OH)2 Mg(OH)2 WHICH OF THE FOLLOWING IS A STRONG ACID IN AQUEOUS SOLUTION? HC2H3O2 HC1 HC1O2 H2S HC1O WHICH OF THE FOLLOWING REACTIONS IS NOT AN ACID-BASE REACTION? CaO + SiO2 rightarrow CaSiO3 CH3CHO + H2 rightarrow CH3CH2OH PO4^3- + H2O rightarrow HPO4^2- + OH- Na2O + SO3 rightarrow Na2SO4 BF3 + NH3 rightarrow F3BNH3 ALL OF THE FOLLOWING ARE OXIDATION-REDUCTION REACTIONS EXCEPT: H2(G) + F2 rightarrow 2HF(G) Ca(S) + H2(G) rightarrow CAH2(S) 2K(S) + 2H2O(L) rightarrow 2KOH(AQ) H2(G) 6Li(S) + N2(G) rightarrow 2Li3N(S) Mg3N2(S) + 6H2O(L) rightarrow 3Mg(OH)2(S) + 2NH3(G) WHICH OF THE FOLLOWING IS BEST DESCRIBED AS AN OXIDATION-REDUCTION REACTION? SO2(G) + H20(L) rightarrow H2SO3(AQ) 2C1(G) rightarrow C12(G) 3O2(G) rightarrow 2O3(G) 2NO2(G) rightarrow N2O4(G) SO2(G) + O2(G) rightarrow SO3 WHICH OF THE FOLLOWING REACTIONS INVOLVES NEITHER OXIDATION NOR REDUCTION? N2 + 3H2 rightarrow 2NH3 NH4NO2 rightarrow N2 + 2H2O Cu + 2Ag+ rightarrow Cu^2+ + 2Ag 2CrO4^2- + 2H+ rightarrow Cr2O7^2- + H20 C2H4 + H2 rightarrow C2H6 ASSIGN OXIDATION NUMBERS TO EACH ATOM IN NITROUS ACID. H = +1, N=+5, 0=-l H=+l, N=+5, O=-2 H=+l, N=+3, O=-l H=+l, N=+3, O=0 H=+l, N=+3, O=-2 FOR THE REACTION THAT OCCURS IN A LEAD STORAGE BATTERY, Pb(S) + Pb02(S) + 2H+(AQ) + 2HS04-(AQ) rightarrow 2PbSO4(S) + 2H20(L) THE OXIDIZING AGENT IS HSO4- PbSO4 Pb PbO2 H+ IN THE BALANCED EQUATION 3Na+ + 3OH- + P4 + 2H2O rightarrow 3Na+ + 3H2OP2- + PH3 WHAT IS THE REDUCING AGENT? OH- Na+ H2O P4 PH3 ALL OF THE FOLLOWING REACTIONS ARE CALLED COMBINATION REACTIONS EXCEPT BaO(S) + SO2(G) rightarrow BaSO3(S) C6H10(L) + Br2(L) rightarrow C6H10Br2(L) Br2(L) + H20(L) rightarrow HOBr(AQ) + HBr(AQ) CaC12(S) + 6H2O(L) rightarrow CaC12 * 6H2O(S) 3H2(G) + N2(G) rightarrow 2NH3(G) A 12.0 SAMPLE OF NaOH IS DISSOLVED IN WATER, AND THE SOLUTION IS DILUTED TO GIVE A FINAL VOLUME OF 1.80 L. THE MOLARITY OF THE FINAL SOLUTION IS 6.67 M 0.167 M 0.300 M 0.150 M 1.85 M HOW MANY GRAMS OF LITHIUM NITRATE, LiN03 (68.9 G/MOL), ARE REQUIRED TO PREPARE 511.5 mL OF A 0.101 M LiN03 SOLUTION? 0.000750 G 3.56 G 0.281 G 349 G 0.0735 G WHICH SUBSTANCE WOULD PRODUCE 2 MOL OF PARTICLES PER MOLE OF SOLUTE WHEN DISSOLVED IN WATER? NH4CH3COO CH2O CO2 SO2 A1(NO3)3 WHAT MASS OF H3PO4 (98 G/MOL) IS PRESENT IN 59.7 L OF A 0.0438 M SOLUTION OF H3P)4? 0.0267 G 0.00390 G 2.56 Times 10^2 G 1.34 Times 10^5 G 13.9 G WHICH OF THE FOLLOWING IS A CORRECT STATEMENT OF CHARLE'S LAW, V/T = k THE VOLUME OF A GAS VARIES PROPORTIONALLY WITH THE PRESSURE THE VOLUME OF A GAS SAMPLE VARIES DIRECTLY WITH THE ABSOLUTE TEMPERATURE ALL GAS SAMPLES OF THE SAME VOLUME OF STP CONTAIN THE SAME NUMBER OF ATOMS THE PRESSURE OF A GAS SAMPLE VARIES INVERSELY WITH THE VOLUME. ALL GAS SAMPLES OF THE SAME VOLUME AT STP CONTAIN THE SAME NUMBER OF MOLECULES. THE DENSITY OF A GAS IS 3.48 G/L AT STP. WHAT IS ITS MOLAR MASS? 115.7 G/MOL 104.7 G/MOL 6.4 G/MOL 22.4 G/MOL 78.0 G/MOL WHAT VOLUME OF AMMONIA GAS, MEASURED AT 455.9 MM HG AND 57.4 DEG C, IS REQUIRED TO PRODUCE 2.78 G OF AMMONIUM SULFATE ACCORDING TO THE FOLLOWING BALANCED CHEMICAL EQUATION? 2NH3(G) + H2SO4(AQ) rightarrow (NH4)2SO4(S) 0.0002233 L 0.000931 L 0.476 L 7.38 L 1.90 L CALCIUM NITRATE WILL REACT WITH AMMONIUM CHLORIDE AT SLIGHTLY ELEVATED TEMPERATURES, AS REPRESENTED IN THE EQUATION Ca(NO3)2(S) + 2NH4C1(S) rightarrow 2N2O(G) + CaC12(S) + 4H2O(G) WHAT IS THE MAXIMUM VOLUME OF N20 AT STP THAT COULD BE PRODUCED USING A 2.40-MOL SAMPLE OF EACH REACTANT? 6.55 Times 10^2 L 108 L 1.86 Times 10^-2 L 53.8 L 22.4 L WHAT IS THE PARTIAL PRESSURE OF CARBON DIOXIDE IN A CONTAINER THAT CONTAINS 7.64 MOL OF OXYGEN, 1.68 MOL OF NITROGEN, AND 1.42 MOL OF CARBON DIOXIDE WITH A TOTAL PRESSURE OF 529 MM HP? 376 MMHG 80.6 MMHG 82.7 MMHG 69.9 MMHG 529 MMHG A SAMPLE OF HYDROGEN IS COLLECTED BY WATER DISPLACEMENT AT 23.0 DEG C AND AN ATMOSPHERIC PRESSURE OF 735 MMHG. ITS VOLUME IS 568 ML. AFTER WATER VAPOR IS REMOVED, WHAT VOLUME WOULD THE HYDROGEN OCCUPY AT THE SAME CONDITIONS OF PRESSURE AND TEMPERATRE? (THE VAPOR PRESSURE OF WATER AT 23.0 DEG C IS 21 MMHG)509 mL 539 mL 552 mL 568 mL 585 mL