A) Determine the ionic formula of one Cr+6, 4 oxygen atoms (polyatomic ion with a charge of -8) and 2H+ ions. B) Find the molar mass of one mole of the compound in part A. C) The Michigan standard for the maximum permissible level of Cr+6 in ground water is 0.10 mg/L. You take 1.00 Liter of ground water and discover that there is 0.15 mg of Cr+6 present. Convert 0.15mg of Chromium (the +6 charge does NOT change the molar mass) to moles of Cr. D) How many formula units of H2CrO4 are in the number of moles of Cr+6 you calculated in part C? r

A) Determine the ionic formula of one Cr+6, 4 oxygen atoms (polyatomic ion with a charge of -8) and 2H+ ions. B) Find the molar mass of one mole of the compound in part A. C) The Michigan standard for the maximum permissible level of Cr+6 in ground water is 0.10 mg/L. You take 1.00 Liter of ground water and discover that there is 0.15 mg of Cr+6 present. Convert 0.15mg of Chromium (the +6 charge does NOT change the molar mass) to moles of Cr. D) How many formula units of H2CrO4 are in the number of moles of Cr+6 you calculated in part C? r

Chemistry: The Molecular Science

5th Edition

ISBN:9781285199047

Author:John W. Moore, Conrad L. Stanitski

Publisher:John W. Moore, Conrad L. Stanitski

Chapter4: Energy And Chemical Reactions

Section: Chapter Questions

Problem 120QRT

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You need 300. mL of 0.500-M K2Cr2O7. Which method is best to prepare this solution? Explain your choice. (a) Dilute 250. mL of 0.600-M K2Cr2O7 to 300. mL. (b) Add 50.0 mL water to 250. mL of 0.250-M K2Cr2O7. (c) Dilute 125 mL of 1.00-M K2Cr2O7 to 300. mL. (d) Add 30.0 mL of 1.50-M K2Cr2O7 to 270. mL of water.
Five white, 500-mg uncoated ascorbic acid (AA) tablets with an average weight of 0.6152-g were pulverized in a mortar. A sample of the powdered ascorbic acid weighing 0.4700-g was placed in an iodine flask and was dissolved in 50-mL H2SO4 then 5-g of KBr was added to the resulting solution. The solution was titrated with 47.81-mL of 0.09640 N STD. KBrO3 to reach a faint yellow endpoint then 3-g KI and 5-mL Starch TS. The blue color solution is then titrated with 2.73-mL of 0.09123 N STD. Na2S2O3 to reach the disappearance of the blue iodostarch complex. MW: KBrO3 = 167.0 ; KIO3 = 214.0 ; Na2S2O3 = 158.11 ; C6H8O6 = 176.12 Compute the milligrams of pure AA per tablet from the assay. 293.3 mg 502.5 mg None of the choices 383.9 mg
A mixture containing KCl and NaBr was analyzed by Mohr's method. A mass of 0.31011 g of the mixture was dissolved in 50 mL of water, the Na2CrO4 indicator was added, and it was titrated with a 0.11011 mol/L AgNO3 solution. The endpoint was 36.011 mL. What are the % m/m concentrations of KCl and NaBr in the mixture?
A 0.2088 g sample of primary-standard-grade sodium carbonate, Na₂CO₃ (105.99 g/mol) was dissolved in water and diluted to 100.00 mL in a volumetric flask. A 30.00-mL portion of this solution was used to standardize a hydrochloric acid (HCl) solution based on the following reaction: CO₃²⁻ + 2H⁺ → H₂O + CO₂. If 36.09 mL of the HCl solution was used to reach the end point, what is the molarity of the HCl?
The first goal is to make the oxalic acid standard solution. You measure 1.5232 g of oxalic acid on an analytical balance, add it to a 250-mL volumetric flask and add deionized H2O to a final volume of 250.0 mL. Molar mass of H2C2O4•2H2O = 126.07 g/mol Mass of H2C2O4•2H2O = 1.5232g Volume of H2C2O4•2H2O solution = 250.0mL What is the Molarity H2C2O4 standard solution ?
The first goal is to make the oxalic acid standard solution. You measure 1.5232 g of oxalic acid on an analytical balance, add it to a 250-mL volumetric flask and add deionized H2O to a final volume of 250.0 mL. Molar mass of H2C2O4•2H2O = 126.07 g/mol Mass of H2C2O4•2H2O = 1.5232g what is the Number of moles of H2C2O4•2H2O?
Potassium hydrogen phthalate is used as a primary standard in finding the concentration of a solution of sodium hydroxide by the reaction KHC8H4O4 + NaOH → NaKC8H4O4 + H2O. What is the molarity of the base if 32.75 mL is required to titrate 1.732 g of the primary standard?
1. A sample of pure sodium oxalate, Na2C2O4 , weighing 0.2856 g is dissolved in water, sulfuric acid is added, and the solution titrated at 70°C , requiring 45.12 mL of a KMNO4 solution. The end point is overrun and back-titration is carried out with 1.74 mL of a 0.1032 N solution of oxalic acid. Calculate the normality of the KMNO4 solution. Hint: A redox reaction is involed between oxalate and permanganate. Look at the changes in oxidation state by determining the balanced redox reaction: 5C20,2 + + 2MN2+ 2 Mn04 + 10H* → 10CO2 + 8H20
1. A buffer is prepared using lactic acid (HLac) and sodium lactate (NaLac). 0.300 dm3 of the 0.500 mol·dm–3 HLac solution is mixed with 0.300 dm3 of the 0.300 mol·dm–3 NaLac solution to prepare the buffer. Ka for lactic acid (HLac) is 1.4 x 10-4 What will the pH of the above solution be after 5.0 cm3 of 0.200 mol·dm–3 NaOH has been added to only 100.0 cm3 of this buffer? 2. Data in the table below were collected at 25°C for the following reaction:2 I–(aq) + S2O82–(aq) I2 (aq) + 2 SO42-(aq) a) Determine the rate law for the reaction. b) Calculate the rate constant, giving the correct units for k.
When drinking water is disinfected with chlorine, an undesired byproduct, chloroform (CHCl3), may form. Suppose a 70-kg person drinks 2 L of water every day for 70 years with a chloroform concentration of 0.08 mg/L (the drinking water standard). Potency factor for chloroform = 6.1 x 10-3 (mg/kg-day)-1 The upper-bound cancer risk for this individual. a. 0.545 b. 5.45x10-6 c. 5.45x10-4 d. 5.45x10-10 e. 14x10-6 If a city with 300,000 people in it also drinks the same amount water described in the above question, how many extra cancers per year would be expected? Assume the standard 70-year lifetime. a. 0.163 b. 1.63x10-4 c. 1.63x10-3 d. 1.63x10-6 e. 6x10-2
1. Calcium in a sample solution is determined by atomic absorption spectroscopy (AAS). A stock solution of calcium is prepared by dissolving 1.834 g CaCl, 2H,0 in water and diluting to 1 litre. From this stock solution, the second stock solution is prepared by the dilution factor of 10. Three standard solutions of calcium are prepared from the second stock solution with the following dilution factor: 20 (first standard solution), 10 (second standard solution) and 5 (third standard solution). A blank solution is prepared as well. Absorbance signals of AAS are as follows: 1.5 (blank solution), 10.6 (first standard solution), 20.1 (second standard solution), 38.5 (third standard solution), 29.6 (sample solution). (Molar mass; Ca = 40.00 g mol-, CI = 35.45 g mol-, 0 = 16.00 g mol-', H = 1.00 g mol-1) a. Construct ONE (1) plot that could be used to represent the calibration curve. b. From the plot of Q1a, determine the amount of calcium in parts per million.
A 0.3147-g sample of a primary-standard grade Na2C2O4 was dissolved in dilute H2SO4 and titrated with 31.67 mL of dilute KMnO4: 2 MnO4- + 5 C2O42- + 16 H+ → 2 Mn2+ + 10 CO2(g) + 8 H2O Calculate the molarity of the KMnO4 solution.