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Using the from problem e above, if 10.2 g of H_2S were obtained in the lab numbe

ID: 499159 • Letter: U

Question

Using the from problem e above, if 10.2 g of H_2S were obtained in the lab numbers (actual yield), what is the percent yield? _____ % How many grams of K_2C_2O_4, potassium oxalate, would contain 182 grams of pure potassium? What is the molarity of a solution made by dissolving 6.08g of sodium acetate, CH_3COONa, in water, and diluting it to a total volume of 0.750L? _____ M How many grams of strontium nitrate, Sr(NO_3)_2, are needed to prepare 3.40 times 10^3 mL of a 0.925 solution? _____ g To what volume should 50.0mL of a 6.00M HCl stock solution be diluted to obtain a 1.50M HCl solution? How much water should be used? A 38.5mL sample of 0.875M AgNO_3, solution is mixed with 51.0mL sample of 0.744M NaCl solution. The AgCl precipitated has a mass of 2.06g. Calculate the limiting reactant, the theoretical yield and percent yield. AgNO_3(aq) + NaCl_(aq) rightarrow AgCl_(s) + NaNO_3(aq)

Explanation / Answer

a)

molarity of

6.08 g opf sodium acetate in V = 0.75 L

mol of NaAcetate = 82.0343 g/mol

so

mol = mass/MW = 6.08/82.0343 = 0.07411 mol of NaAc

M = mol/V = 0.07411 / 0.75 = 0.0988 M of

b)

grams of Sr(NO3)2 required fo

V = 3400 mL of M = 0.925 M solution

M = mol/V

mol = MV = (0.925)(3.400) = 3.145 mol of Sr(NO3) =required

MW = 211.63 g/mol

mass = mol*MW = 211.63 *3.145 = 665.576 gof Sr(NO3)2 required

c)

Apply Dilution law

M1¨V1 = M2V2

50*6 = 1.5*V

V = 50/1.5*6 = 200 mL

d)

V = 38.5 mL of M = 0.875 AgNO#

V = 51 mL of M = 0.744 NaCl

mol of Ag+ = MV = 38.5*0.875 = 33.6875 mmol of Ag+

mol of Cl- = MV = 51*0.744 = 37.944 mmol of Cl

clearly, Ag+ is limiting

theoretical yield --> 33.6875 mmol of Ag+ --> 33.6875 mmol of AgCl

mass = molñ*MW = 33.6875 *10^-3*143.32 =4.828092 g of AgCl are expected

% yield = real/Theoretical * 100% = 2.06/4.828092 *100 = 42.6669 %