Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download The Mole: A Measurement of Matter
Document related concepts
Transcript
The Mole: A Measurement of Matter Describe how Avogadro’s number is related to a mole of any substance Solve problems involving mass in grams, amount in moles, and number of atoms of an element The Mole and Avogadro’s Number SI unit that measures the amount of substance 1 mole = 6.022 x 1023 representative particles Representative particles are usually atoms, molecules, or formula units (ions) Examples Substance Representative Chemical Particle Formula Representative Particles in 1.00 mol Nitrogen Atom 6.022 x 1023 N atoms Sodium Atom Na 6.022 x 1023 atoms Calcium Atom Ca 6.022 x 1023 atoms Solve How many atoms are in one mole of 1. Mercury (Hg) 2. Gold (Au) 3. Silver (Ag) 4. Iron (Fe) How many moles of magnesium are in 1.25 x 1023 atoms of magnesium? Divide the number of atoms or molecules given in the example by 6.022 x 1023 Divide (1.25 x 1023) by (6.022 x 1023) Express in scientific notation Answer = 2.08 x 10-1 mol Mg How many moles of silver, Ag, are in 3.01 x 1023 atoms of silver? Answer 0.500 mol Ag Molar mass Mass (in grams) of one mole of a substance Broad term (can be substituted) for gram atomic mass, gram formula mass, and gram molecular mass Can be unclear: What is the molar mass of oxygen? O or O2 ? - element O or molecular compound O2 ? Molar Mass The mass of one mole of atomic hydrogen is 1.01 grams. The mass of one mole of aluminum is 26.98. What is the mass of one mole of barium? Zinc? Neon? Calculating the Molar Mass What is the mass in grams of 3.50 mol of the element copper? 1. Look up the mass on the periodic table. Round it to two decimal places. (63.55 g) 2. Multiply 63.55 g by 3.50 moles. Answer is 222 g Cu (Three significant figures because three figs in 3.50) Solve What is the mass in grams of 2.00 mol of nitrogen? Solve What is the mass in grams of 1.20 x 108 atoms of copper, Cu? 1. Convert the given amount of atoms to the amount of moles by dividing by Avogadro’s number. Answer: 1.99 x 10-16 2. The amount in moles is then multiplied by molar mass (63.55) Answer: 1.27 x 10-14 g Cu
