Relative Mass and the Mole: Understanding Atomic Masses and Ratio of Masses, Slides of Chemistry

Download Relative Mass and the Mole: Understanding Atomic Masses and Ratio of Masses and more Slides Chemistry in PDF only on Docsity! Chemistry(4) Mrs. Day-Blattner 3 March, 2020 Period 3 3 March, 2020 Agenda ● Return the “The Measure of a Mole” work ● “The new definition of the kilogram is based on Planck’s Constant” Agree https://www.youtube.com/watch?v=Oo0jm1PPRuo ● Relative Mass and the Mole: Pogil Packet ○ With a group (11 mins) ○ All together ○ Turn in ● Quick Check (and exit ticket) Chicken Quail Ratio of numbers of eggs Ratio of masses of eggsNumber of eggs in sample Mass of the sample Number of eggs in sample Mass of the sample 1 37.44g 1 2.34g 1:1 16:1 10 374.4g 10 23.4g 1:1 16:1 438 16, 399g 438 1, 025 g 1:1 16:1 1 dozen 449.3 g 1 dozen 28.08 g 1:1 16:1 1 million 37,440,000g 1 million 2,340,000g 1:1 16:1 3. a) Which basket would be heavier? The one containing chicken eggs. b.) The basket of chicken eggs would be 16 times heavier than the basket of quail eggs. c) Each individual chicken egg is 16 times heavier than each individual quail egg, so if there are the same number of eggs in each basket, the total mass of the chicken egg basket will bet 16 times greater. 4. a) What mass of quail eggs would the farmer need to weigh out to have the same number of eggs in both samples? 32.0kg of chicken eggs. 1 = x gives x = 2.0 kg 16 32.0kg Read this? Let’s take what we learned in the egg model and apply it to atoms. Like eggs, atoms of the same element may have slightly different masses (remember isotopes). The periodic table lists an average atomic mass for the atoms in a sample of each element. These masses are recorded in “atomic mass units” (amu) where 1 amu is approximately equal to the mass of a proton (or neutron.) 6. What is the ratio of the mass of an oxygen atom to the mass of a sulfur atom? 6. What is the ratio of the mass of an oxygen atom to the mass of a sulfur atom? 1: 2 8. When two samples contain the same number of atoms... 8. When two samples contain the same number of atoms...the ratio of the sample masses will be equal to the ratio of the atoms’ masses. 9. The mass ratio does not depend on the number of atoms in a sample, as long as the number is the same for both elements so we do not really need to know how many atoms are in 1 mole. Read this? A long time ago chemists discovered what you have just discovered (or re-remembered) The relative masses of the elements can be used to “count” atoms. If you measure out a sample equal to an atom’s atomic mass in grams, you always end up with the same number of atoms. Chemists call that quantity the mole, a quantity of any sample whose mass is equal to its atomic mass in grams. Model 3 - Molar Mass 12. Look at a periodic table. What number in each element box would a chemist use to find the values in the “Average Mass of a Single Particle” column in Model 3? Model 3 - Molar Mass 12. Look at a periodic table. What number in each element box would a chemist use to find the values in the “Average Mass of a Single Particle” column in Model 3? The average atomic mass values, in amu. 14. Which sample contains more atoms, 18.016 amu of water or 18.016 g of water? 14. Which sample contains more atoms, 18.016 amu of water or 18.016 g of water? A gram is a MUCH larger unit than the atomic mass unit, so the 18.016 g sample has more atoms. 18.016 amu is the mass of a single water molecule. 15. If the formula mass of iron(II) sulfate (FeSO4) is 151.9 amu, what is the molar mass of iron(II) sulfate 16. Use a periodic table to calculate the molar mass of ammonia (NH3) - Show your work. Atomic masses N 14.00 amu 3H 3(1.00) = 3.00 amu Sum 17 amu Molar mass is 17 g/mol Or one mole would be 17g. 17. How would the number of atoms in a 1.01 g sample of hydrogen compare to the number of atoms in a 63.55 g sample of copper? 17. How would the number of atoms in a 1.01 g sample of hydrogen compare to the number of atoms in a 63.55 g sample of copper? The number of atoms would be the same, since these a both 1 mole samples. 18. Fill in the blanks using a periodic table. Be sure to include units of g or amu on all masses. 1 atom of helium has a mass of 4.00 amu. 1 mole of helium contains 6.022 x 1023 atoms, and has a mass of 4.00g. 1 formula unit of calcium chloride (CaCl 2 ) has a mass of 40.078 +(2)(35.453) = 110.98 amu. 1 mole of CaCl 2 contains 6.022 x 1023 formula units, and has a mass of 110.98g. Relative Mass and the Mole Extension Questions 19. a) Fluorine gas consists of diatomic molecules of fluorine (F 2 ). How many molecules of fluorine are in one mole of fluorine? 6.022 x 1023 molecules b) What is the mass of 1 mole of fluorine gas? 19 amu x 2 = 38 amu 1 mole is 38 g of F 2 19. a) Fluorine gas consists of diatomic molecules of fluorine (F 2 ). How many molecules of fluorine are in one mole of fluorine? 6.022 x 1023 molecules b) What is the mass of 1 mole of fluorine gas? 19 amu x 2 = 38 amu 1 mole is 38 g of F 2 c) How many atoms of fluorine are in this sample? 6.022 x 1023molecules x 2 atoms = 1.204 x 1024atoms 1molecule