Mass percentages

The ranking of carbohydrates/polysaccharides according to mass percentages of subclasses reads ... [Pg.459]

In order to draw the property - composition diagram, coordinates are usually chosen so that the ideal system values correspond with the additive law regarding concentration [313]. It is known, for instance, that in an ideal system, molar volume changes additively with the concentration, and is expressed in molar fractions or molar percentages, whereas specific volume changes linearly with the concentration, and is expressed in mass fractions or mass percentages. [Pg.148]

As a caution, however, one must carefully purify the sample since small amounts of low molecular weight impurities can contribute significantly to II, even though their mass percentage in the sample is small. [Pg.373]

Because the mass percentage composition is independent of the size of the sample— in the language of Section A, it is an intensive property—every sample of the substance has that same composition. A principal technique for determining the mass percentage composition of an unknown organic compound is combustion analysis. Chemists commonly send samples to a laboratory or agency for combustion analysis and receive the results as mass percentage composition (see Section M). [Pg.71]

Sf.I.f-Tfst F.1B The compound a-pinene, a natural antiseptic found in the resin of the pinon tree, has been used since ancient times by Zuni healers. A 7.50-g sample of a-pinene contains 6.61 g of carbon and 0.89 g of hydrogen. What are the mass percentages of carbon and hydrogen in a-pinene ... [Pg.71]

If the chemical formula of a compound is already known, its mass percentage composition can be obtained from the formula. [Pg.71]

EXAMPLE F.l Sample exercise The mass percentage of an element in a compound... [Pg.71]

Suppose wc are generating hydrogen from water to use as a fuel and need to know how much hydrogen a given mass of water can provide. What is the mass percentage of hydrogen in water ... [Pg.71]

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% ... [Pg.71]

From Mass percentage of H mass of FI atoms mass of H20 molecules... [Pg.71]

Self-Test F.2A Calculate the mass percentage of Cl in NaCI. [Pg.71]

Self-Test F.2B Calculate the mass percentage of Ag in AgN03. [Pg.71]

To convert the mass percentage composition obtained from a combustion analysis into an empirical formula, we must convert the mass percentages of each type of atom into the relative numbers of atoms. The simplest procedure is to imagine that we have a sample of mass 100 g exactly. That way, the mass percentage... [Pg.71]

EXAMPLE F.2 Sample exercise Determining the elemental composition from mass percentage composition... [Pg.72]

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,... [Pg.72]

The mass percentage composition of a compound that assists in the coagulation of blood is 76.71 % C, 7.02% H, and 16.27% N. Determine the empirical formula of the compound. [Pg.72]

STRATEGY Divide each mass percentage by the molar mass of the corresponding element to obtain the number of moles of that element found in exactly 100 g of the compound. Divide the number of moles of each element by the smallest number of moles. If fractional numbers result, then multiply by the factor that gives the smallest whole numbers of moles. [Pg.72]

Self-TfsT F.4B The mass percentage composition of the compound thionyl difluoride is 18.59% O, 37.25% S, and 44.16% F. Calculate its empirical formula. [Pg.73]

The empirical formula of a compound is determined from the mass percentage composition and the molar masses of the elements present. [Pg.73]

F.l Citral is a fragrant component of lemon oil that is used in colognes. It has the molecular structure shown. Calculate the mass percentage composition of citral (black = C, gray = H, red = O). [Pg.74]

F.3 What is the mass percentage composition of I-carnitine, C7HhN03, a compound that is taken as a dietary supplement to reduce muscle fatigue ... [Pg.75]

F.5 A metal M forms an oxide with the formula M20, for which the mass percentage of the metal is 88.8%. (a) What is the molar mass of the metal (b) Write the name of the compound. [Pg.75]

F.14 Paclitaxel, which is extracted from the Pacific yew tree Taxus brevifolia, has antitumor activity for ovarian and breast cancer. It is sold under the trade name Taxol. On analysis, its mass percentage composition is 66.11% C, 6.02% H, and 1.64% N, with the balance being oxygen. What is the empirical formula of paclitaxel ... [Pg.75]

F.16 Cacodyl, which has an intolerable garlicky odor and is used in the manufacture of cacodylic acid, a cotton herbicide, has a mass percentage composition of 22.88% C, 5.76% H, and 71.36% As and a molar mass of 209.96 g-mol. What is the molecular formula of cacodyl ... [Pg.75]

F.19 The CO, produced by the combustion of hydrocarbons contributes to global warming. Rank the following fuels according to increasing mass percentage of carbon (a) ethene, C2H4 (b) propanol, C3H-OI I (c) heptane, C-Hl6. [Pg.75]

H.21 Phosphorus and oxygen react to form two different phosphorus oxides. The mass percentage of phosphorus in one of these oxides is 43.64% in the other, it is 56.34%. [Pg.90]

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... [Pg.101]

J.10 (a) White phosphorus, which has the formula P4, burns in air to form compound A, in which the mass percentage of phosphorus is 43.64%, with the remainder oxygen. The mass spectrum of A yields a molar mass of 283.9 g-mol. Write the molecular formula of compound A. (b) Compound A reacts with water to form compound B, which turns litmus red and has a mass percentage composition of 3.087% 11 and 31.60%... [Pg.101]

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 ... [Pg.113]

From mass percentage = Mass percentage iron... [Pg.114]

L.26 Sulfur is an undesirable impurity in coal and petroleum fuels. The mass percentage of sulfur in a fuel can be determined by burning the fuel in oxygen and dissolving the SO, produced in water to form aqueous sulfuric acid. In one experiment, 8.54 g of a fuel was burned, and the resulting sulfuric acid was titrated with 17.54 mL of 0.100 m NaOH(aq). (a) Determine the amount (in moles) of H2S04 that was produced, (b) What is the mass percentage of sulfur in the fuel ... [Pg.116]

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