Chemical equations, balancing calculations from

Evaluating Results Use the balanced chemical equation to calculate the mass of copper that should have been produced from the sample of iron you used. Use this number and the mass of copper you actually obtained to calculate the percent yield. 

Use the balanced chemical equation to find, from the number of moles of the given substance, the number of moles of the substance sought in the calculation. 

Remind students to multiply 1 the standard molar entropy of each reactant and product by the appropriate coefficient from the balanced chemical equation when calculating the standard entropy of a reaction. 

You are given the mass of the reactant AgNOj and the actual yield of the product Ag2Cr04. You need to write the balanced chemical equation and calculate the theoretical yield by making these conversions grams of silver nitrate to moles of silver nitrate, moles of silver nitrate to moles of silver chromate, moles of silver chromate to grams of silver chromate. The percent yield can be calculated from the actual yield of product and the calculated theoretical yield. 

The process of using a chemical equation to calculate the relative amounts of reactants and products involved in the reaction is called doing stoichiometric calculations. To convert between moles of reactants and moles of products, we use mole ratios derived from the balanced equation. 

To determine the limiting reactant, first calculate the number of moles of each reactant present. Then determine how these numbers of moles correspond to the stoichiometric ratio indicated by the balanced chemical equation for the reaction. For each reactant, use the stoichiometric ratios from the balanced chemical equation to calculate how much of the other reactants would be required to react completely. 

Balancing a Chemical Equation 244 Calculating the Quantities of Reactants and Products in a Chemical Reaction 283 Calculating the Moles of Product from a Limiting Reactant 289... 

Given a quantity in moles of reactant or product, use a mole-mole factor from the balanced chemical equation to calculate the number of moles of another substance in the reaction. 

Section 6.11, when we calculated the enthalpy change for an overall physical process as the sum of the enthalpy changes for a series of two individual steps. The same rule applied to chemical reactions is known as Hess s law the overall reaction enthalpy is the sum of the reaction enthalpies of the steps into which the reaction can be divided. Hess s law applies even if the intermediate reactions or the overall reaction cannot actually be carried out. Provided that the equation for each step balances and the individual equations add up to the equation for the reaction of interest, a reaction enthalpy can be calculated from any convenient sequence of reactions (Fig. 6.30). 

Entropy changes are important in every process, but chemists are particularly interested in the effects of entropy on chemical reactions. If a reaction occurs under standard conditions, its entropy change can be calculated from absolute entropies using the same reasoning used to calculate reaction enthalpies from standard enthalpies of formation. The products of the reaction have molar entropies, and so do the reactants. The total entropy of the products is the sum of the molar entropies of the products multiplied by their stoichiometric coefficients in the balanced chemical equation. The total entropy of the reactants is a similar sum for the reactants. Equation... 

The number of moles of KCIO, may be calculated from the number of moles of O, by means of the balanced chemical equation, and that value is then converted to mass. 

Each calculation uses the stoichiometric coefficients from the balanced chemical equation and the molar mass of the reactant. 

M HC2H302. We base our calculation, as usual, on the balanced chemical equation. The concentration of H30+ from the added HC1 is represented by jc. ... 

We first balance the chemical equation and then calculate the value of AG° with data from Appendix D, and finally calculate the value of with the use of AG° = -RT nK. 

This balanced equation can be read as 4 iron atoms react with 3 oxygen molecules to produce 2 iron(III) oxide units. However, the coefficients can stand not only for the number of atoms or molecules (microscopic level) but they can also stand for the number of moles of reactants or products. So the equation can also be read as 4 mol of iron react with 3 mol of oxygen to produce 2 mol ofiron(III) oxide. In addition, if we know the number of moles, the number of grams or molecules may be calculated. This is stoichiometry, the calculation of the amount (mass, moles, particles) of one substance in the chemical equation from another. The coefficients in the balanced chemical equation define the mathematical relationship between the reactants and products and allow the conversion from moles of one chemical species in the reaction to another. 

The relationship above gives a way of converting from grams to moles to particles, and vice versa. If you have any one of the three quantities, you can calculate the other two. This becomes extremely useful in working with chemical equations, as we will see later, because the coefficients in the balanced chemical equation are not only the number of individual atoms or molecules at the microscopic level, but also the number of moles at the macroscopic level. 

The mass of the sample is converted to moles by using the molar mass. The moles of titrant may be calculated from a consideration of the moles of sample and the balanced chemical equation. The moles of titrant divided by the liters of solution gives the molarity of the solution. 

The pipeted volume is converted to moles by multiplying the liters of solution by its molarity. The moles of titrant are determined from the mole ratio in the balanced chemical equation for the reaction. The molarity of the solution is calculated by dividing the moles of titrant by the liters of titrant used. 

Convert the masses of the reactants and products to moles using their molar masses. Using the mole ratios from the balanced chemical equation, it is possible to determine how much material should react or be produced. These calculated values can be compared to the observed values. 

The final concentration of each reactant is calculated from the final volume and the volume and concentration of the solution pipeted into the volumetric flask. The calibration curve is used to find the equilibrium concentration. Using the balanced chemical equation, the equilibrium concentrations of the other substances may be calculated. 

Comparing and Contrasting Compare the ratio of moles of iron to moles of copper from the balanced chemical equation to the mole ratio calculated using your data. 

Surfactant Properties. Hydrophyllic-lipophyllic balance (HLB) was calculated from equation 2 (3) Molecular weights and chemical compositions were obtained from the literature or from the manufacturers. The partition coefficients and HLB values were not... 

While the chemical mass balance receptor model is easily derivable from the source model and the elements of its solution system are fairly easy to present, this is not the case for multivariate receptor models. Watson (9) has carried through the calculations of the source-receptor model relationship for the correlation and principal components models in forty-three equation-laden pages. 

First, you must have a balanced chemical equation on whidh to base your calculation Because the three C atoms of C3H8 are converted to 3C02- and the 8H atoms are converted to 4H20, you can readily see that the 10 oxygen atoms needed m this much C02 and H20 must come from Therefore,... 

The balanced chemical equation for a reaction is used to set up the conversion factor from one substance to another and that conversion factor, the mole ratio for the reaction, is applied to the moles given to calculate the moles required. 

To calculate A S° for the reaction, subtract the standard molar entropies of all the reactants from the standard molar entropies of all the products. Look up the S° values in Table 17.1 or Appendix B and remember to multiply the S° value for each substance by its coefficient in the balanced chemical equation. 

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