5.06 grams of oxygen 2.14 grams of K 0. To confirm your answer, compare the calculated value to the weighted mass displayed on the periodic table. Using a periodic table, give the molar mass of the following: H Se Ne Cs Fe Convert to moles and find the total number of atoms. Add up all and assign unit as grams/mole. Multiply the atomic weight of each element with its number of atoms present in the compound. Make use of the chemical formula to determine the number of atoms of each element in the compound. The atomic mass of oxygen (use percent natural abundance data from Table 2.5.1) would be calculated as follows:Ītomic mass = (%1)(mass 1) + (%2)(mass 2) + (%3)(mass 3) How to find the molar mass of a compound Step 1. For chlorine, there are only two naturally occurring isotopes so there are only two terms.Ītomic mass = (%1)(mass 1) + (%2)(mass 2) + ⋯Īnother example: oxygen exists as a mixture that is 99.759% 16O, 0.037% 17O and 0.204% 18O. For elements with no stable isotopes, the mass number of the isotope with the longest half-life is in parentheses. This is repeated until there is a term for each isotope. Cobalt salts can be given to certain animals in small doses to correct mineral deficiencies. The amount we need is very small, and the body contains only about 1 milligram. The weighted average is determined by multiplying the percent of natural abundance by the actual mass of the isotope. Cobalt is an essential trace element, and forms part of the active site of vitamin B12. Options for hiding the symbol or name of the elements provide a handy learning aid for memorizing the periodic table. The atomic mass of an element is the weighted average of the atomic masses of the naturally occurring isotopes of that element. Use this periodic table for calculating molar mass for any chemical formula. Finally, add together the total mass of each element to get the molar mass of O: 15.9994 g/mol 15.9994 g/mol. Why? The reason is that we need to take into account the natural abundance percentages of each isotope in order to calculate what is called the weighted average. Multiply the number of atoms by the atomic weight of each element found in steps 1 and 2 to get the mass of each element in O: Molar Mass (g/mol) O (Oxygen) 1 × 15.9994 15.9994. = 35.968 \,u \nonumber \]Īs you can see, the average atomic mass given in the last column of the table above (35.453) is significantly lower.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |