DATE: 10/2/2012 LAB 3 – PHYSICAL & CHEMICAL PROPERTIES *Adapted from LabPaq Purpose: To determine whether certain changes in matter are chemical or physical, and to describe the changes in detail using observational skills Observations and Experimental Data: Substance: Mg Color: Silver Odor: Slighty Effect of Heat: Particles moved, bubbles flowing up to top Solub. or Reaction w/cold H2O: No reaction Solub. or Reaction w/hot H2O: Bubbles produced from the gas Litmus test: Red turned blue and blue had no change Dilute HCl: Sizzle, steams, heat output Dilute NaOH: Gas was formed. Substance: Cu Color: Redish Brown Odor: None Effect of Heat: Became darker, almost purple like. Solub.
Calculate the mass of KCl required to prepare 250. mL of 0.250 M solution. 3. Calculate the volume of 0.30 M KCl solution that contains 6.00 g of KCl. 6.00 g x 1 mole x 1 L = 0.27 L 74.6 g 0.30 mol 4. Calculate the volume of 0.250 M H2SO4 that contains 0.250 g H2SO4.
Conclusion 10 Grams of Potassium chlorate when decomposed produces 3.915576 grams oxygen gas and 6.083363 grams potassium chloride Atomic Weight of Magnesium Introduction In this lab we will determine the atomic weight of magnesium by measuring the amount of hydrogen gas evolved when hydrochloric acid reacts with magnesium. The reaction is as follows: Mg + 2HCl -> H2 + Mg2+ (aq) + 2Cl- (aq) There is a one to one relationship between the number of moles of hydrogen gas evolved and the
25 cm3 of a solution of sodium hydroxide reacts with 15 cm3 of 0.1 mol/dm3 HCl. What is the molar concentration of the sodium hydroxide solution? 4. Succinic acid has the formula (CH2)n(COOH)2 and reacts with dilute sodium hydroxide as follows: (CH2)n(COOH)2 + 2NaOH → (CH2)n(COONa)2 + 2H2O 2.0 g of succinic acid were dissolved in water and the solution made up to 250 cm3. This solution was placed in a burette and 18.4 cm3 was required to neutralise 25 cm3 of 0.1 moldm-3 NaOH.
An aqueous solution of ammonium sulfate is allowed to react with an aqueous solution of lead(II) nitrate. Identify the solid in the balanced equation. A) (NH4 )2 SO4 B) Pb(NO3 )2 C) PbSO4 D) NH4 NO3 E) There is no solid formed when the two solutions are mixed. ____ 11. An aqueous solution of sodium carbonate is reacted with an aqueous solution of calcium chloride.
The precipitate(s) for the above reaction is/are: A) Silver nitrate B) Aluminum bromide C) Silver bromide D) Aluminum nitrate E) There is no precipitate 18 – 37: For each of the two REDOX reactions below, perform the following: A) Balance the following equation and place the final answer in the boxes provided; show all work on the exam pages. B) Identify the oxidizing and reducing reagents. C) Assign the oxidation numbers to the elements in bold on both sides of the equation. D) Identify the oxidation and reduction half-reactions by placing LEO and GER, respectively, above the arrows in each half-reaction. E) NOTE that illegible writing will not be graded.
In well A2: Place 10 drops of Magnesium Sulfate, MgSO4 c. In well A3: Place 10 drops of Zinc Nitrate, Zn(NO3)2 d. In well A4: Place 10 drops of Iron (III) Chloride, FeCl3 e. In well A5: Place 10 drops of Copper (II) Sulfate, CuSO4 3. Take the metal solids from your LabPaq; there should be one piece each of magnesium, zinc, and iron plus two pieces of lead. NOTE: Magnesium and lead oxidize very easily and an almost invisible oxidation layer may coat the metal. To insure good reactions you should scrape the surface of those metals with a pocketknife or remove the oxidation layer by rubbing the metal pieces with steel wool or something similar. Evidence that a reaction is taking place is the formation of bubbles or a coating on the metal immersed into the solution.
This reaction can be summed up using the following formula: 5Fe2++8H++MnO4- →5Fe3++Mn2++4H2O After standardization, the potassium permanganate solution is then titrated with 3 different magnesium oxalate solutions. To find the concentration of the C2O42- the balanced net ionic redox reaction formula is used: 5C2O42-+16H++2MnO4- →10CO2+2Mn2++8H2O It is important to note the addition of sulfuric acid (9M H2SO4) in performing this experiment because of the following reasons: 1) Sulfuric acid keeps the iron (II) from air oxidizing into iron (III) 2) Sulfuric acid keeps the iron (II) from hydrolyzing into Fe(OH)2 3) Sulfuric
To do that we had to count the molar mass (M) of zinc sulfate. Then we multiplied the amount of zinc sulfate in moles with the molar mass. Then the answer was the mass (m) of the zinc sulfate to add in grams. M(ZnSO4) = (65.38 + 32.06 + 4 x 16.00) g/mol = 161.44 g/mol n (ZnSO4) = 0.02 mol M (ZnSO4) = 161.44
Test Tube Reactants Products Reaction Type A Copper (II) Sulfate + Magnesium Copper + Magnesium Sulfate Single Displacement B Calcium Chloride + Magnesium Sulfate Magnesium Chloride + Calcium Sulfate Double Displacement C Sodium Carbonate + Magnesium Sulfate Magnesium Carbonate + Sodium Sulfate Double Displacement 3. For Test tube a I had to replace copper with magnesium because on the reactivity chart magnesium is more reactive than copper. For test tube b I had to switch the places of the elements calcium and magnesium since it was a double replacement. For test tube c I had to switch the element sodium and magnesium to form a new compound. 4.