Conversion factor molar mass

Caicuiate the mass of each reactant and product by multiplying the number of moles by the conversion factor molar mass. 

Solution To calculate the number of H atoms, we first must convert grams of urea to moles of urea using the molar mass of urea. This part is similar to Example 3.2. The molecular formula of urea shows there are four moles of H atoms in one mole of urea molecule, so the mole ratio is 4 1. Finally, knowing the number of moles of H atoms, we can calculate the number of H atoms using Avogadro s number. We need two conversion factors molar mass and Avogadro s number. We can combine these conversions... 

Before you can solve any stoichiometry problem, you must have the reaction equation and the conversion factors between moles and quantities of Given and Wanted substances. For convenience, we will use the expression starting steps to describe these items. Thus, complete the starting steps means to write and balance the equation, if it is not given, and determine the conversion factors. Molar mass is the conversion factor in this section others will appear later. 

Molar mass can be thought of as a conversion factor between mass in grams and number of moles. These conversions are essential in chemistry, because chemists count amounts of substances in moles but routinely... 

Biological Sample Mass Units Conversion Factor Molar Units Reft... 

Apply the conversion factor. Substitute mass Ca = 325 g, inverse molar mass Ca(OH)2 = 1 mol/74.10 g, and solve. 

Conversions between mass, moles, and the number of particles are summarized in Figure 10.11. Note that molar mass and the inverse of molar mass are conversion factors between mass and number of moles. Avogadros number and its inverse are the conversion factors between moles and the number of representative particles. To convert between moles and the number of moles of atoms or ions contained in the compound, use the ratio of moles of atoms or ions to 1 mole of compound or its inverse, which are shown on the upward and downward arrows in Figure 10.11. These ratios are derived from the subscripts in the chemical formula. 

Unfortunately, we cannot count particles—at least, not directly. Instead, we measure masses or other macroscopic quantities. These can be converted into numbers of particles. You already know how to do this conversion with mass, using molar mass as a conversion factor between mass (in grams) and number of particles (in moles) (see Section 7.5). Equation 10.1 can also be interpreted as, Four moles of NH3 molecules react with five moles of O2 molecules to produce four moles of NO molecules and six moles of H2O molecules. ... 

The molar mass of CO2 is a conversion factor between mass (in grams) and amount (in moles) of CO2. Suppose we want to find the number of CO2 molecules in a sample of dry ice (solid CO2) with a mass of 10.8 g. This calculation is analogous to Example 2.8, where we found the number of atoms in a sample of copper of a given mass. We begin with the... 

The dimensions of permeabiUty become clear after rearranging equation 1 to solve for P. The permeabiUty must have dimensions of quantity of permeant (either mass or molar) times thickness ia the numerator with area times a time iaterval times pressure ia the denomiaator. Table 1 contains conversion factors for several common unit sets with the permeant quantity ia molar units. The unit nmol/(m-s-GPa) is used hereia for the permeabiUty of small molecules because this unit is SI, which is preferred ia current technical encyclopedias, and it is only a factor of 2, different from the commercial permeabihty unit, (cc(STP)-mil)/(100 in. datm). The molar character is useful for oxygen permeation, which could ultimately involve a chemical reaction, or carbon dioxide permeation, which is often related to the pressure in a beverage botde. 

A chemical equation tells us the relations between the amounts (in moles) of each reactant and product. By using the molar masses as conversion factors, we can express these relations in terms of masses. 

A Both the density and the molar mass of Pb serve as conversion factors. 

IB For one conversion factor we need the molar mass ofMgCl2. 

B We need the molar mass of ethyl mercaptan for one conversion factor. 

A The molar mass of halothane is given in Example 3-3 in the text as 197.4 g/mol. The rest of the solution uses conversion factors to change units. 

B Care must be taken to use the proper units/label in each conversion factor. Note, you cannot calculate the molar mass of an impure material or mixture. 

Solve these kinds of problems by using the definition of molarity and conversion factors. In parts (b) and (c), you must first convert your mass in grams to moles. To do so, you divide by the molar mass from the periodic table (flip to Chapter 7 for details). In addition, be sure you convert milliliters to liters. 

If we want an amount other than 1 mol, we use the molar mass as a conversion factor from the stated number of moles to the mass required ... 

Then use this molarity as a conversion factor to calculate the number of moles of solute in the stated volume of solution. The mass of solute is given and the number of moles of solute present is now known therefore, to find the molar mass of the solute, divide the mass by the amount. To avoid rounding errors, do the numerical calculation at the end. 

In effect, molar mass acts as a conversion factor between numbers of molecules and mass. If you know the mass of a sample, you can calculate how many molecules you have if you know how many molecules you have, you can calculate their total mass. Note, though, that it s always necessary when using a molar mass to specify the formula of the substance you re talking about. For example, 1 mol of hydrogen atoms, H, has a molar mass of 1.0 g/mol, but 1 mol of hydrogen molecules, H2, has a molar mass of 2.0 g/mol. 

Now that we know how many moles of ethylene we have (0.536 mol), we also know from the balanced equation how many moles of HC1 we need (0.536 mol), and we have to do a mole-to-gram conversion to find the mass of HC1 required. Once again, the conversion is done by calculating the molecular mass of HC1 and using molar mass as a conversion factor ... 

The problem gives the mass of sucrose and asks for a mass-to-mole conversion. Use the molar mass of sucrose as a conversion factor, and set up an equation so that the unwanted unit cancels. 

Use molar mass of Cl2 Use coefficients in as a conversion factor the balanced equation to find mole ratios... 

First, find out how many moles of Cl2 are in 25.0 g of Cl2. This gram-to-mole conversion is done in the usual way, using the molar mass of Cl2 (70.9 g/mol) as the conversion factor ... 

We need to calculate the amount of methyl tert-bu tyl ether that could theoretically be produced from 26.3 g of isobutylene and compare that theoretical amount to the actual amount (32.8 g). As always, stoichiometry problems begin by calculating the molar masses of reactants and products. Coefficients of the balanced equation then tell mole ratios, and molar masses act as conversion factors between moles and masses. 

Next, find how many moles of ethyl alcohol are in 40.0 g by using molar mass as a conversion factor ... 

We therefore need to find how many grams of diethyl ether are in 0.435 mol, using molar mass as the conversion factor ... 

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