Explore BrainMass
Share

Explore BrainMass

    Stoichiometry

    Isotope Occurrence and Natural Abundance

    Boron has only two naturally occurring isotopes. The mass of boron-10 is 10.01294 amu and the mass of boron-11 is 11.00931 amu. Use the atomic mass of boron to calculate the relative abundance (%) of boron-10, and the relative abundance (%) of boron-11. *I know the average amu for boron is 10.81. I don't understand how you so

    Molality of Ions in Aluminum Sulfate

    What is the molality of a solution of aluminum sulfate that contains 37.0 g of Al2(SO4)3 dissolved in 172.5 g of water? Use molar masses with at least as many significant figures as the data given. What is the molality of each of the ions in solution?

    Molar Concentration of Acetone Solution

    Prepare an acetone solution by placing 10.0 ml of pure acetone in a 50 ml size volumetric flask, and diluting to the mark with distilled water. What is the molar concentration of this solution? Density of acetone=0.7857 g/ml.

    Calculating Molarity of NH3

    Calculate the molarity of a NH3 solution made up of 30.0 grams of NH3 in 70.0 grams of water. The density of the solution is 0.982 g/ml. Significant figures should be taken into effect.

    Chrysoberyl (Beryllium Dialuminate) Source

    Chrysoberyl a semi precious stone it is a source of beryllium and is known as beryllium di-aluminate. A piece was analysed with the following results: 12.7g of beryllium di-aluminate contained 0.9g of beryllium and 5.4g of aluminium. Q. Calculate the the mass of oxygen in the sample of beryllium di-aluminate. And from the abouve

    Molarity and Mass Percent

    What is the molarity of a 17% by mass of sodium acetate, CH3COONa in water? The density of the solution is 1.09 g/mL.

    Gasoline Composition To Produce Specified Oxygen Percentage

    Calculate the mass percent of methanol, ethanol, and MTBE each that must be present in gasoline to yield a mixture of 2.9 % oxygen by weight. Hint given: Calculate percent oxygen in each compound. I don't have the density of the gasoline in the question or in the textbook. However, all I can find relevant in the textbook i

    Empirical Formula of a Compound

    A 10.0 mg sample of a compound containing only carbon and hydrogen is burned in oxygen producing 30 mg CO2 and 16.3 mg of H2O. Using this data determine the empirical formula of this compound.

    Percentage Yield in a Chemical Reaction

    If the percent yield of the reaction shown below is 95.50%, how many grams of Cr2O3 must be used to produce 380.0 g of COCl2? Cr2O3 + 3CCl4 = 2CrCl3 + 3COCl2

    CrO42- ions added to PbCrO4 solution to start precipitation

    You have a Lead(II) chromate solution with a concentration of 1.64e-07 mol/L. How many moles of chromate ions do you have to add to just about start precipitation of lead chromate assuming the volume does not change appreciably? n(CrO4^2-)= ? mol

    Removing Lead Using Chloride Precipitate

    You have a Lead (II) solution, and you want to remove the Lead by forming a Lead (II) chloride precipitate. How large do you have to make the chloride concentration at least to be sure that the amount of Lead left in solution is less than 0.28 mg/L? Express in mol/L.

    Fermi Energies of Fermi Gases

    See attachment for full problem and symbols. Calculate the Fermi energies Eg (in units of eV) and the corresponding Fermi temperatures TF for: a. Liquid 3He (density 0.0823 g cm^-3) b. Electrons in aluminium (valence 3, density 2.7 g cm^-3) c. Neutrons in the nucleus of 16O. The radius r of a nucleus scales roughly as r =

    Solubility, Concentration and Precipitation Problems

    At 25 degrees C, the value of Ksp for PbCl2(s) is 1.6x10^-5 and the value of Ksp for AgCl(s) is 1.8x10^-10. 1) If 60.0mL of 0.0400 M NaCl (aq) is added to 60.0mL of 0.0300M Pb(NO3)2(aq) will a precipitate form? Assume that the volumes are additive. Show calculations to support your answer. 2) Calculate the equilibrium value

    Interpreting Chemical Measurements

    A wastewater sample was collected from the influent of a primary sedimentation tank. The following results were obtained from tests conducted on 50 mL wastewater samples. Determine total solids (TS), total suspended solids (TSS), and total dissolved solids (TDS). Tare mass of evaporating dish = 62.003 g Mass of eva

    normality of solution

    For each of the following solutions, the mass of solute taken is indicated, along with the total volume of solution prepared. Calculate the normality of each solution. (a) 0.139 g NaOH; 10.5 mL N (b) 11.5 mg Ca(OH)2; 100. mL N (c) 12.5 g H2SO4; 195 mL N

    Precipitation of Calcium Oxalate

    Calcium oxalate, CaC2O4, is very insoluble in water. What mass of sodium oxalate, Na2C2O4 is required to precipitate the calcium ion from 36.5 mL of 0.106 M CaCl2 solution?

    solution from stock

    If you have a 2 M stock solution of Tris Buffer, a 0.5 M stock solution of Magnesium chloride, and a bottle of crystalline sodium chloride. Use these reagents to make 500 ml of a solution containing 50 mM Tris, 5 mM of MgCl2, and 0.25 M sodium chloride.

    Toxicity of TCDD in Animal Based Foods

    Given that the average TEQ of animal-based foods is about 0.7 picograms of TCDD equivalent per gram, and that the LD50 for 2,3,7,8-TCDD is about 0.001 mg/kg body weight, what mass(kg) of animal-based food would you have to consume to ingest a fatal dose of it?

    Concentration of Glucose in Blood

    On average, glucose makes up about 0.10% of human blood, by mass. What is the approximate concentration of glucose in blood in milligrams per deciliter?

    Picograms

    Im confused on how to do this problem all together. I can't find help in the book because their answers are hard to follow. If you could work this out and explain how each step was done so I could understand how to do it that would be awesome. Thank you Given that the average TEQ of animal-based foods is about 0.7 picograms o

    mass percent of solute

    What is the mass percent of solute in each of the following solutions? a.) 155 mg NaCl/g solution b.) 0.242 L methanol (d= 0.791 g/mL)/kg water c.) 3.8 L ethylene glycol (d= 1.114 g/mL) in 6.5 L propylene glycol(d= 1.036 g/mL)