Chemical formulas determining

To determine the molar mass of a substance, we need its chemical formula and elemental molar masses. From the chemical formula, determine the number of moles of each element contained in one mole of the substance. Multiply each elemental molar mass by the number of moles of that element, and add. 

The chemical formula of a compound contains essential information about its composition. The formula identifies which elements are present, and it states the number of atoms of each kind present in one unit of the compound. We need the chemical formula of a substance to calculate its molar mass. In fact, almost all chemical calculations require the correct chemical formula. How are chemical formulas determined in the first place ... 

Growth—Vitamin A aids in the building and growth of body cells hence, it is essential for body growth. Because of this, prior to the time that vitamin A was isolated and its chemical formula determined, its potency in food was measured by growth rate. Since animals on a vitamin A-free diet stop growing when their bodies are depleted of its stores, foods to be assessed were fed to these animals in... 

The reqmred values of are determined from the initial numbers of moles, and the values of dji come directly from the chemical formulas of the species. These are shown in the accompanying table. 

The phase diagram for the copper-antimony system is shown on the next page. The phase diagram contains the intermetallic compound marked "X" on the diagram. Determine the chemical formula of this compound. The atomic weights of copper and antimony are 63.54 and 121.75 respectively. 

Using the Molecules Database on the Web site for this book, determine the chemical formula and draw the I ewis structure of (a) anthracene (b) phosgene ... 

To determine a chemical formula from a molecular picture, count the atoms of each type and arrange the symbols in the correct order using the guidelines. 

Construct the structural formulas and determine the chemical formulas from the following line drawings ... 

Determine the chemical formulas of calcium chloride, magnesium nitrate, and potassium dihydrogen... 

C03-0012. Determine the chemical formulas of potassium sulfide, barium perchlorate, and calcium... 

Determine the correct chemical formulas of potassium permanganate, dinitrogen tetroxide, nickel(II) chloride hexahydrate, sodium hydrogen phosphate, and iron(Itl) oxide. 

C03-0015. Determine the chemical formulas of barium chloride dihydrate, chromium(III) hydroxide, and sulfur trioxide. 

The line drawing and chemical formula of Sevin, a common insecticide, appear in the margin. Determine the molar mass of Sevin. 

To determine a chemical formula, we would like to count the atoms of each element in one molecule of the compound. Atoms are too small to count, but we might hope to measure the number of moles of each element present in one mole of the compound. Unfortunately, there is no direct experimental method for measuring moles. Instead, laboratory experiments give the masses of the various elements contained in some total mass of the compound. 

The elemental analysis of a compound is usually determined by a laboratory that specializes in this technique. A chemist who has prepared a new compound sends a sample to the laboratory for analysis. The laboratory charges a fee that depends on the type and number of elements analyzed. The results are returned to the chemist as a listing of mass percent composition. The chemist must then figure out which chemical formula matches this composition. If a chemist has reason to expect a particular chemical formula, the observed percentages can be matched against the calculated percentages for the expected formula. This process is illustrated in Example 3-13. 

Analysis of ibuprofen, the active ingredient in several over-the-counter pain relievers, shows that it contains 75.7% carbon, 8.8% hydrogen, and 15.5% oxygen. The mass spectrum of ibuprofen shows that its molar mass is less than 210 g/mol. Determine the chemical formula of this compound. 

The ratio of cations and anions in a solution of a salt is determined by its chemical formula. For example, a solution of NaCl contains Na cations and Cl anions in 1 1 ratio a 1.0 M solution of sodium chloride is 1.0 M in each of Na" and Cl". hi contrast, NiCl2 contains two moles of Cl" anions for eveiy one mole of... 

We can use the ideal gas equation to calculate the molar mass. Then we can use the molar mass to identify the correct molecular formula among a group of possible candidates, knowing that the products must contain the same elements as the reactants. The problem involves a chemical reaction, so we must make a connection between the gas measurements and the chemistry that takes place. Because the reactants and one product are known, we can write a partial equation that describes the chemical reaction CaC2(. ) +H2 0(/) Gas -I- OH" ((2 q) In any chemical reaction, atoms must be conserved, so the gas molecules can contain only H, O, C, and/or Ca atoms. To determine the chemical formula of the gas, we must find the combination of these elements that gives the observed molar mass. 

C05-0072. Gaseous hydrocarbons, which contain only carbon and hydrogen, are good fuels because they bum in air to generate large amounts of heat. A sample of hydrocarbon with m— 1.65 g exerts a pressure of 1.50 atm in a 945-mL bulb at 21.5 °C. Determine the molar mass and chemical formula of this hydrocarbon. 

Follow the six-step procedure, using the chemical formula to determine the bonding framework. 

C09-0021. Hydrazine, occasionally used as a rocket fuel, has the chemical formula N2 H4. Determine the Lewis stmcture of hydrazine and draw a picture that shows the shape of the molecule. 

C09-0083. Fluorine forms compounds whose chemical formula is XF4 with elements from groups 14, 16, and 18. Determine the Lewis structure, describe the shape, and draw a ball-and-stick model of Gep4, SeF4, and Xep4. 

C09-0105. Describe the bonding and determine the empirical chemical formula of the silicon-oxygen network of zircon. 

Determine the chemical formulas and Lewis structures of these two substances. Describe then-bonding completely, including the geometry and hybridization for each carbon atom. 

C17-0072. For each molecular picture shown in the figure, determine the chemical formula, identify it as an acid or base, and draw a picture of its conjugate partner. 

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