#CACL MOLAR MASS PERIODIC TABLE HOW TO#

For this type of calculation, the molar masses of two different substances must be used-be sure to keep track of which is which. It should be a trivial task now to extend the calculations to mass-mass calculations, in which we start with a mass of some substance and end with the mass of another substance in the chemical reaction. How many grams of N 2 are needed to produce 2.17 mol of NH 3 when reacted according to this chemical equation?ģ0.4 g (Note: here we go from a product to a reactant, showing that mole-mass problems can begin and end with any substance in the chemical equation.) Now, using the molar mass of NH 3, which is 17.03 g/mol, we get: Start by using the balanced chemical equation to convert to moles of another substance and then use its molar mass to determine the mass of the final substance. The conversions are the same, but they are applied in a different order. How many grams of NH 3 will be produced when 33.9 mol of H 2 are reacted according to this chemical equation? The steps are the same but are performed in reverse order. How many moles of Al 2O 3 will be produced when 23.9 g of H 2O are reacted according to this chemical equation?ĢAlCl 3 + 3H 2O(ℓ) → Al 2O 3 + 6HCl(g) AnswerĪ variation of the mole-mass calculation is to start with an amount in moles and then determine an amount of another substance in grams. The last digit in our final answer is slightly different because of rounding differences, but the answer is essentially the same. From the balanced chemical equation, we construct a conversion factor between the number of moles of AlCl 3 and the number of moles of HCl:Īpplying this conversion factor to the quantity of AlCl 3, we get:Īlternatively, we could have done this in one line: Now we can use this quantity to determine the number of moles of HCl that will form. The molar mass of AlCl 3 is 133.33 g/mol, which we have to invert to get the appropriate conversion factor: We will do this in two steps: convert the mass of AlCl 3 to moles and then use the balanced chemical equation to find the number of moles of HCl formed. How many moles of HCl will be produced when 249 g of AlCl 3 are reacted according to this chemical equation?ĢAlCl 3 + 3H 2O(ℓ) → Al 2O 3 + 6HCl(g) Solution

Sometimes the answer may be slightly different from doing it one step at a time because of rounding of the intermediate answers, but the final answers should be effectively the same. The units still cancel appropriately, and we get the same numerical answer in the end. However, it is mathematically equivalent to perform the two calculations sequentially on one line: In this last example, we did the calculation in two steps. So, we will get 1.159 mol of AlCl 3 if we react 123.2 g of Cl 2. Using this conversion factor with the molar quantity we calculated above, we get:

The numbers in the conversion factor come from the coefficients in the balanced chemical equation: Now that we have the quantity in moles, we can use the balanced chemical equation to construct a conversion factor that relates the number of moles of Cl 2 to the number of moles of AlCl 3. We must invert this fraction so that the units cancel properly: The molar mass of Cl 2 (which we get from the atomic mass of Cl from the periodic table) is 70.90 g/mol.

#CACL MOLAR MASS PERIODIC TABLE HOW TO#

We know how to do this by simply using the molar mass of Cl 2 as a conversion factor. So to use the balanced chemical equation to relate an amount of Cl 2 to an amount of AlCl 3, we need to convert the given amount of Cl 2 into moles. How can we determine how many moles of AlCl 3 we will get when the reaction is complete? First and foremost, chemical equations are not balanced in terms of grams they are balanced in terms of moles. We can add that conversion factor as another step in a calculation to make a mole-mass calculation, where we start with a given number of moles of a substance and calculate the mass of another substance involved in the chemical equation, or vice versa.įor example, suppose we have the balanced chemical equation: Recall that the molar mass can be determined from a chemical formula and used as a conversion factor. Mole-mole calculations are not the only type of calculations that can be performed using balanced chemical equations. From a given mass of a substance, calculate the mass of another substance involved using the balanced chemical equation.From a given mass of a substance, calculate the moles of another substance involved using the balanced chemical equation.From a given number of moles of a substance, calculate the mass of another substance involved using the balanced chemical equation.

Cacl molar mass periodic table