CHEM 01LA Lecture Notes - Lecture 1: Liquid, Manganese, Standard Deviation

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23 Nov 2014

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Practice our abilities to measure objects and other liquids by using balances and volumetric tubes to find the densities of our solids and liquids. Determine the density of the metallic solid by measuring the volume of water that is displaced by the solid. Part a: weigh the coin in grams to 3 sig figs. 4. record the mass in lab notebook leave the coin on balance re-zero the balance by pressing tare bar: place another coin on the balance, weigh it both again and record its mass. 8. remove two coin from balance re-zero balance: weigh both coins together (record mass as mass of coins #1 and #2 weighed together , weigh other objects to practice skills. 9. repeat step 8 twice by repeating steps 5 and 6: find density again from additional data, if the density of three trials vary by more than 1%, make another trial.

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Need help answering the pre - lab questions

Chemistry 1010 Laboratory Fall 2016 Lab: Percent Sugar Content of Beverages ave you ever been to the ocean? Does it seem that you can float or swim much easier in the ocean than in a swimming pool? Seawater is more dense than freshwater due to the presence of dissolved salt in the cean As a result, our buoyancy-ability to float-is greater in salt water than in plain water. What factors of a particular substance is dissolved in it? Background The density of a pure substance is a characteristic physical property that can be used to identify the substance does not depend on the amount of the substance. The density of any material is determined by measuring its mass and volume and then dividing the mass by the volume. The mass of a substance can be measured directly using a balance. The volume of a liquid can be measured directly using special laboratory glassware, such as a graduated cylinder, buret, or pipet. In this experiment, liquild volumes will be measured using a graduated cylinder Density is defined as the ratio of mass per unit volume. It is an "intensive" property, that is, it The density of a solution depends on its concentration, that is, how much solid is dissolved in the liquid. The higher the concentration of solid, the greater the density of the solution. A convenient way to express concentration is in units of weight percent, which corresponds to the number of grams of sollid that are present in 100 g of solution. A 20% salt solution is prepared by dissolving 20 g of sodium chloride (table salt) in 80 g of water to give a final mass of 100 g of solution. When the density of a solution is plotted on a graph against the concentration of the solution, a regular pattern becomes evident, specifically that density is directly proportional to the concentration of solid in the solution. A 20% salt solution, for example, has a higher density and higher concentration of solid than a 10% salt solution. If the densities of several solutions of known concentration are determined experimentally and plotted on a graph, a calibration curve can be drawn to show a straight-line relationship between the density of a solution and the concentration of solid (note: the calibration curve in this lab reveals a linear (straight-line) relationship, but not all calibration curves are linear). The calibration curve can then be used to find the concentration of solid in an unknown solution simply based on experimentally measuring the density of the solution. Experiment Overview The purpose of this experiment is to determine the percent sugar content in beverages. The density of five reference" solutions will be determined in Part A. The reference solutions contain known amounts sugar " of sugar (0-20%). Their densities will be plotted on a graph to obtain a calibration curve of density versus nt sugar concentration. In Part 8, the densities of two beverages will also be determined, and the The results will be compared against the information provided on the nutrition labels for these beverages 1. if the following mass and volume data are used to calculate the density of solution, how many cal libration curve, created from the data in Part A, will be used to find the percentage of sugar they contain. Pre-Lab Questions significant figures are allowed in the calculated density? Mass of solution 12.53 g: volume of solution = 8.27 mL Calculate the density of the solution described in Question #1 (Hint: This is a 2-step problem. Then calculate the percent sugar in the beverage.) According to its nutrition label, orange soda 2. 3. First, use the density to convert the 355-mL serving size to grams. Lab: Percent Sugar Content of Beverages

Zinc and Copper(II) Sulfate Materials: Two test tube rack, 1 M CuSO_4 (copper(II) sulfate notation). Zn(s) For all the experiments in pans C-F, use small quantities. For solids, use the amount of compound that will fit on the tip of a spatula or small scoop. Carefully pour small amounts of liquids into your own beakers and other container. Measure out 3 ml, of water in a test tube. Use this volume as a reference level for each of the experiments. Do not place droppers or stirring rub into reagent bottles. They may contaminate a reagent for the entire class. Discard unused chemicals as indicated by your instructor. B.l Pour 3 ml. (match the reference volume) of the blue solution. 1 M CuSO_4 (one molar copper(II) sulfate), into each of two test tubes. Obtain a small piece of zinc metal. Describe the appearance of the CuSO_4 solution and the small piece of zinc metal. Add the Zn metal piece to the CuSO_4 solution in one of the test tubes. The CuSO_4 solution in the other test tube it your reference for the initial solution color. Place the test tubes in your test tube rack and observe the color of the CuSO_4 solutions and the Zn piece again at 15 and 30 minutes. Pour the CuSO_4 solutions into the sink followed by a large amount of water. Rinse the piece of zinc with water and place it in a recycling container as directed by your instructor. B.2 Balance the equation given for the reaction. The symbol (aq) means aqueous (dissolved in water). Unbalanced equation: Zn(s) + CuSO_4(aq) rightarrow Cu(s) + ZnSO_4(aq) B 3 Identify the type of reaction that that occurred. Metals and HCl Materials: Three test tubes, test tube rack, small pieces of Cu(s), Zn(s), and Mg(s) metal 1 M HCl Caution: HCl it a carrot ire acid. Handle carefully! C.l Place 3 mL of I M HCl (match your reference volume from part Cu(s) in each of three test tubes. Describe the appearance of each metal. Carefully add a metal piece to the acid in each of the test tubes. Record any evidence of reaction such at bubbles of gas (H_2). Carefully pour off the acid and follow with large quantities of water to dilute. Rinse the metal pieces with water, dry, and return to your instructor C.2 Balance the equation given for each metal that gave a chemical reaction. If there was no reaction, cross out the products and write NR for no reaction. Unbalanced equations: 1.Cu(s) + HCl(aq) rightarrow CuCl_2(aq) + H_2(g) 2. Zn(s) + HCl(aq) rightarrow ZnCl_2(aq) + H_2(g) 3. Mg(s) + HCl(aq) rightarrow MgCl_2(aq) + H_2(g) C.3 Identify the type of reaction for each chemical reaction that occurred. Reactions of Ionic Compounds Materials: Three (3) test tubes, test tube rack Dropper bottle sets of 0.1 M solutions: CaCl_2, Na_3PO_4, BaCl_2, Na_2SO_4, FeCl_3, KSCN For each of these reactions, two substances will be mixed together. Describe your observations of the reactants before you mix them and then describe the products of the reaction. Look for changes in color, the formation of a solid (solution turns cloudy), the dissolving of a solid, and/or the formation of a gas (bubbling). Balance the equations for the reactions. Dispose of the solutions properly. D.1 Place 20 drops each of 0.1 M CaCl_2 (calcium chloride) and 0.1 M Na_3PO_4 (sodium phosphate) into a test tube. Describe any changes that occur. Identify the type of reaction for each chemical reaction that occurred. Unbalanced equation: CaCl_2(aq) + Na_3PO_4(aq) rightarrow Ca_3(PO_4)_2(s) + NaCl(aq).

Using this information: I used 4.00 g potassium dichromate. The amount of Iron ll is 4.00 gram in 2nd flask. Used grey moose vodka 2.00 ml and filled flask with water. This was the 2% vodka solution. For the experiment I used 5.00ml of the vodka and added 35.00 ml of more water to make it 1/8 of 2% or 0.25% of the original. With this information and the answer's i have placed in the table please help with remainder of questions. Need to work to understand answers so I will get correct on upcoming test. Thanks.

Calculate the concentration of the dichromate ion in the first volumetric flask.

Calculate the concentration of the iron (II) ion in the second volumetric flask.

Experiment 2: Titrate the Vodka Sample

Lab Results

Record the following lab data in the table below. If you had to repeat one of the titrations, disregard the value that was different.

(a) volume of potassium dichromate solution added to the Erlenmeyer flask in mL	5.00ml
(b) coarse titration volume of iron (II) solution range in mL	14.10 -14.15 ml
(c) volume of iron (II) solution delivered from the burette in mL during the first fine titration	14.13ml
(d) volume of iron (II) solution delivered from the burette in mL during the second fine titration	14.11ml
(e) average volume of iron (II) solution used in the fine titrations	14.12ml
(f) the color of the analyte solution at the end point of the titration	purple
(g) the color of the analyte solution after adding the indicator	dark green

Data Analysis

Record and calculate the quantities in the table below using the data from your dichromate titrations. Use an average value for the volume of iron (II) solution used in the titration. If one of your values is very different, and you had to perform the titration three times, disregard the value that was very different when computing the average.

(a) volume of potassium dichromate solution added to the Erlenmeyer flask in mL 5.00ml
(b) moles of dichromate ion added to the Erlenmeyer flask
(c) average volume of iron (II) solution delivered from the burette in mL 14.12ml
(d) moles of iron (II) ions delivered from the burette
(e) moles of excess dichromate ions that reacted with the iron (II) ions (remember that the ratio in which they react is 1 dichromate : 6 iron (II))
(f) moles of dichromate that reacted with the ethanol in the vodka (Subtract excess dichromate ions that reacted with the iron (II) ions from the original moles of dichromate ion present.)
(g) moles of ethanol in the 5 mL diluted vodka sample according to the stoichiometric ratio of 2 dichromate ions to 3 ethanol molecules

The amount of alcohol in a drink is typically reported as percent alcohol by volume. Volume percent or volume/volume percent (% v/v) most often is used when preparing solutions of liquids. Volume percent is defined as:
% v/v = V_solute/V_solution Ã 100
Find the percent alcohol (ethanol) by volume for the vodka used in the lab by following the steps outlined in the table below.

(a) given the molar mass of ethanol of 46.07 g/mol, calculate the mass of alcohol (ethanol) in the tested sample solution
(b) given the density of ethanol of 0.7893g/ml, find the volume in mL of ethanol present in the diluted vodka solution
(c) record the volume of vodka used in the experiment in mL
(d) find the percent alcohol by volume (% v/v) in the diluted vodka solution
(e) the diluted vodka solution was prepared by diluting 2.00 mL vodka to 100.00 mL. Calculate the dilution factor used (N:1)
(f) multiply the percent alcohol by volume in the diluted vodka solution by the dilution factor to obtain the % v/v alcohol in the original vodka solution

Conclusions

The Grey Moose vodka tested in this lab reports a percent alcohol by volume of 40.0% on its label. How does your value compare to the reported one? If the values are different, give one possible experimental error that might have contributed to the difference.

Potassium permanganate is another strong oxidizing substance similar to potassium dichromate. An acidic solution of purple permanganate ions can get reduced to colorless Mn²⁺ ions in the presence of ethanol. Write down the redox reaction between permanganate and ethanol, and balance it using the half-reaction method.

Besides vodka, there are other colorless alcohol-containing beverages that can be titrated following the procedure in your lab. Given the average values for the percent alcohol by volume listed in the table below, which beverage do you expect to use the least amount of iron (II) standard solution during the titration? Assume all lab procedures stay the same.

	% alcohol by volume
White rum	37.0%
Vermouth	18.0%
White whine	12.0%

CHEM 01LA Lecture Notes - Lecture 1: Liquid, Manganese, Standard Deviation

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