Moles mass and

Converting Between Moles, Mass, and Number of Particles... 

This last example uses a dimensional analysis to convert between moles, mass, and volume. How many liters will 150 grams of S02(g) occupy at STP Remember the importance of keeping careful track of the numbers, units, and substance in a problem such as this one. Start by converting to moles and then to volume ... 

You will use the mole and molar mass to make conversions among moles, mass, and number of representative particles. 

Skill 8.5 Applying the law of conservation of mass to solve problems involving moles, mass, and volume and problems involving solution chemistry... 

You have learned that different kinds of representative particles are counted using the mole. In the last section, you read how to use molar mass to convert among moles, mass, and number of particles of an element. Can you make similar conversions for compounds and ions Yes, you can, but to do so you will need to know the molar mass of the compounds and ions involved. 

I Balanced chemical equations can be interpreted in terms of moles, mass, and representative particles (atoms, molecules, formula units). 

The equation relating the amount of substance in moles, mass and molar mass can be used to calculate any quantity given the values of the other two ... 

The barometric formnla can be revmtten in a different form. Remember that m/K = niNfjKTNf) = (MIR) (M is a mole mass and R is the universal gas constant). Therefore,... 

The Mole, Molar Mass, and Mole-Gram Conversions... 

In this book, we will express our thermodynamic quantities in SI units as much as possible. Thus, length will be expressed in meters (m), mass in kilograms (kg), time in seconds (s), temperature in Kelvins (K), electric current in amperes (A), amount in moles (mol), and luminous intensity in candella (cd). Related units are cubic meters (m3) for volume, Pascals (Pa) for pressure. Joules (J) for energy, and Newtons (N) for force. The gas constant R in SI units has the value of 8.314510 J K l - mol-1, and this is the value we will use almost exclusively in our calculations. 

During the initial stages (when a < 0.04) of the thermal decompositions of the alkali (Na, K, Rb, Cs) perchlorates [845] (giving MC103), the rates of oxygen evolution from all four salts were approximately the same and independent of particle size and sample mass. Experimental values of E ( 190 kJ mole-1) were low compared with those found by Solymosi [846] for the overall reaction (250—290 kJ mole-1) and also lower than the standard enthalpies for anion breakdown (276—289 kJ mole-1) for... 

Convert between mass and amount in moles by using the molar mass (Example E.4). 

STRATEGY We convert from the given volume of gas into moles of molecules (by using the molar volume), then into moles of reactant molecules or formula units (by using a mole ratio), and then into the mass of reactant (by using its molar mass). If the molar volume at the stated conditions is not available, then use the ideal gas law to calculate the amount of gas molecules. 

Two measures of concentration that are useful for the study of colligative properties, because they indicate the relative numbers of solute and solvent molecules, are mole fraction and molality. We first met the mole fraction, x, in Section 4.8, where we saw that it is the ratio of the number of moles of a species to the total number of moles of all the species present in a mixture. The molality of a solute is the amount of solute species (in moles) in a solution divided by the mass of the solvent (in kilograms) ... 

If these equations are written in terms of mass and then summed over all components, the sum must equal Equation (1.1) since the net rate of mass formation must be zero. When written in molar units as in Equation (1.6), the sum need not be zero since chemical reactions can cause a net increase or decrease in the number of moles. 

For purposes of chemical bookkeeping, it is unnecessary to know the isotopic molar masses and isotopic distributions of the elements. All we need to know is the mass of one mole of an element containing its natural composition of isotopes. These molar masses usually are included in the periodic table, and they appear on the inside front and back covers of this textbook. 

As emphasized in Section 2-, many of the calculations in chemistry involve converting back and forth among the mass of a substance, the number of moles, and the number of atoms and/or molecules. These calculations are all centered on the mole. The connections shown in Figure apply to chemical compounds as well as to atoms of pure elements. Molar mass and Avogadro s number provide links between mass of a sample, the number of moles, and the number of molecules. 

The chemicai formuia identifies the ions that are present in the finai soiution. The formula also tells us how many moles of each ion are present in one moie of the sait. Use mass, molar mass, and volume to calculate molarity. 

First, we must identify the chemistry. This is an acid-base titration in which hydrogen phthalate anions (the acid) react with OH (the base). We use the molar equality of acid and base at the stoichiometric point together with the equations that link moles with mass and volume. 

Hydrogen phthalate has one acidic hydrogen atom. As the net reaction shows, there is a 1 1 molar ratio between hydrogen phthalate and hydroxide HCg Hq O4 + OH Cg Hq O4 + H2 O The number of moles of hydrogen phthalate anions is the same as the number of moles of KHCg Hq Oq, which is calculated from its mass and molar mass ... 

The ideal gas equation can be combined with the mole-mass relation to find the molar mass of an unknown gas PV = nRT (ideal gas equation) and n — (mole-mass relation) if we know the pressure, volume, and temperature of a gas sample, we can use this information to calculate how many moles are... 

Whereas liquids and solids have well-defined densities, the density of a gas varies strongly with the conditions. To see this, we combine the ideal gas equation and the mole-mass relation and rearrange to obtain an equation for... 

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