Solutes mass percentage

Several measures are used to specify the composition of a solution. Mass percentage (colloquially called weight percentage), frequently used in everyday applications, is defined as the percentage by mass of a given substance in the solution. In quantitative chemistry, the most useful measures of composition are mole fraction, molarity, and molality. 

SOLUTION To calculate the mass percentage of hydrogen in water, we simply find the mass of H atoms in 1 mol F120 molecules, noting that there are 2 mol H in 1 mol H20, divide that mass by the mass of 1 mol H2O, and multiply by 100% ... 

SOLUTION We consider a sample of exactly 100 g, then convert the masses into I amounts in moles by dividing the mass percentage for each element by the element s molar mass. The mass of carbon in a sample of vitamin C of mass 100 g is 40.9 g. Because the molar mass of carbon is 12.01 g-moD1,... 

J.9 You are asked to identify compound X, which was extracted from a plant seized by customs inspectors. You run a number of tests and collect the following data. Compound X is a white, crystalline solid. An aqueous solution of X turns litmus red and conducts electricity poorly, even when X is present at appreciable concentrations. When you add sodium hydroxide to the solution a reaction takes place. A solution of the products of the reaction conducts electricity well. An elemental analysis of X shows that the mass percentage composition of the compound is 26.68% C and 2.239% H, with the remainder being oxygen. A mass spectrum of X yields a molar mass of 90.0 g-moF. (a) Write the empirical formula of X. (b) Write... 

The stoichiometric point is reached when all the Fe2+ has reacted and is detected when the purple color of the permanganate ion persists. A sample of ore of mass 0.202 g was dissolved in hydrochloric acid, and the resulting solution needed 16.7 mL of 0.0108 M KMn04(aq) to reach the stoichiometric point, (a) What mass of iron(ll) ions is present (b) What is the mass percentage of iron in the ore sample ... 

To calculate molality, we use Equation, for which we need moles of solute and mass of solvent in kilograms. To find these quantities, it is convenient to consider 100 g of solution, for which the mass percentage is the mass of one component present. 

C17-0121. Vinegar is a dilute aqueous solution of acetic acid. A sample of vinegar has a pH of 2.39 and a density of 1.07 g/mL. What is the mass percentage of acetic acid in the vinegar ... 

The mass percentage of a solution is the mass of the solute divided by the mass of the solution and then multiplied by 100% to yield percentage. 

What is the mass percentage of acetic acid in this solution ... 

STRATEGY The molality is the number of moles of solute per kilogram of solvent. Therefore, consider a solution made with exactly 1 kg of solvent and work out the mass of solute present from the number of moles and the molar mass. Then calculate the mass percentage of solute by dividing the mass of solute by the total mass of the solution and multiply by 100%. 

Calculate the mole fraction and molality of a solute, given the masses or mass percentages of solute and solvent, Examples G.6 and G.7. 

A 0.3249 g sample of stainless steel was analyzed for iron by dissolving the sample in sulfuric acid and titrating the Fe2+ in the resulting solution with 0.018 54 M K2Cr2C>7. If 38.89 mL of the l C CV solution was required to reach the equivalence point, what is the mass percentage of iron in the steel ... 

Mass percentage is frequently used to represent every component of a solution (possibly including the solvent) as a portion of the whole in terms of mass. 

Figure 6.20 (a) Viscosity of solution of poly(y-benzyl-L-glutamate) (PBLG molecular weight 231,000), in m-cresol as a function of shear rate at 29 C for various mass percentages ranging from dilute ( 0.31%) to semidilute (0.31-2.5%) to concentrated isotropic (5-9.5%). The different symbols and lines refer to data taken on different instruments, (b) Zero-shear viscosity as a function of concentration, (reprinted with permission from Mead and Larson, Macromolecules 23 2524. Copyright 1990 American Chemical Society.)... 

Express the concentration of a solute in solution in units of mass percentage, molarity, molality, and mole fraction (Section ff.f. Problems 3-8). 

There are several ways to measure the concentration of a solution, five of which you should know for the MCAT molarity (M), molality ), mole fraction (%), mass percentage and parts per million (ppm). Molarity is the moles of the compound divided by the volume of the solution. Molarity generally has units of mol/L. Molality is moles of solute divided by kilograms of solvent. Molality generally has units of mol/kg and is usually used in formulae for colligative properties. The mole fraction is the moles of a compound divided by the total moles of all species in solution. Since it is a ratio, mole fraction has no units. Mass percentage is 100 times the ratio of the mass of the solute to the total mass of the solution. Parts per million is 106 times the ratio of the mass of the solute to the total mass of the solution. 

A 25 g sample of CuS04 5H20 is dissolved in 55 g of water. What is the mass percentage of the resulting solution ... 

How many grams of CoCl2 6H20 and water are required to obtain 180 g of cobalt(II) chloride solution with a mass percentage of 5% ... 

Skill 16.4 Solving problems involving concentrations of solutions (e.g., molarity, molality, percent by mass percentage)... 

What is the mass percentage of a saccharose solution if 228 grams of it produces 72 grams of glucose after hydrolysis in acidic medium ... 

A 0.40()-g sample of toothpaste was boiled with a 50-mL solution containing a citrate buffer and NaCl to extract the fluoride ion. After cooling, the solution was diluted to exactly 100 niL. The potential of an ion-selective electrode with a Ag-AgCl(sat d) reference electrode in a 25.0-mL aliquot of the sample was found to be -0.1823 V. Addition of 5.0 mL of a solution containing 0.(X)107 mg F /mL caused the potential to change to - 0.2446 V. Calculate the mass percentage of I in the sample. 

In order to solve this system of equations, it is necessary to set the initial density values PiQo of gas components in the bubble. These values cannot be known in advance. The calculations above show that for any initial composition of gas in the bubble, the componential composition of gas is established very quickly and practically does not change afterwards. The initial composition of the solution is conventionally specified by mass percentages Ili of components. Mole fractions are expressed in terms of mass percentages as follows ... 

A 3.455-g sample of a mixture was analyzed for barium ion by adding a small excess of sulfuric acid to an aqueous solution of the sample. The resultant reaction produced a precipitate of barium sulfate, which was collected by filtration, washed, dried, and weighed. If 0.2815 g of barium sulfate was obtained, what was the mass percentage of barium in the sample ... 

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