1. The mole is a unit used to measure very small particles like atoms and molecules and is defined as the number of atoms in exactly 12 grams of carbon-12. 2. One mole contains 6.02 x 10^23 particles and is equal to the substance's molar mass in grams. 3. Only 12g of carbon, 6.02 x 10^23 oxygen atoms, and 22.4L of nitrogen gas are equal to one mole. 1g of hydrogen gas is not equal to one mole.

1. Chemistry Item 03-01 Which is NOT equal to 1 mole? A. 1 g H 2 B. 12 g carbon C. 6.02 x 10 23 oxygen atoms D. 22.4 liter N 2 gas www.upcatreview.com

2. Chemistry Item 03-01 CONCEPT : The MOLE in Chemistry is defined as the amount of substance that contains the same number of particles as there are in 12 g of carbon-12. The mole is analogous to any word that implies a specific value like pair or century but only bigger in value since it is used to count very small particles such as atoms or molecules. www.upcatreview.com

3. Chemistry Item 03-01 CONCEPT : Its value is determined experimentally to be equal to 6.02 x 10 23 which is also known as Avogadro’s number in honor of Italian scientist Amedeo Avogadro. www.upcatreview.com

4. Chemistry Item 03-01 Therefore a mole of any given substance contains 6.02 x 10 23 particles. Particles could be atoms, molecules or ions referring to particles of elements, covalent compounds and ionic compounds, respectively. www.upcatreview.com

5. Chemistry Item 03-01 On the other hand, mole can also be related with a substance mass which is referred to as the molar mass or mass in grams of 1 mole of any substance. For instance, if the atomic mass of the element carbon (C) is 12 amu, then its molar mass would be 12 g. www.upcatreview.com

6. Chemistry Item 03-01 In the same manner for compounds, the molar mass would be the compound’s molecular mass expressed in grams. So for methane, CH 4 having a molecular mass of 16 amu, its molar mass is actually 16 g. www.upcatreview.com

7. Chemistry Item 03-01 To summarize the relationships: 1 mole (of any substance) = molar mass = 6.02 x 10 23 particles (Using the element carbon) 1 mole carbon = 12 grams = 6.02 x 10 23 particles (atoms) of carbon www.upcatreview.com

8. Chemistry Item 03-01 Similarly, molar volume is defined as the volume of one mole of any gas at standard conditions of temperature and pressure. The relationship is actually I mole = 22.4 Liters. Thus oxygen gas (O 2 ) has a molar volume of 22.4 L at standard conditions. www.upcatreview.com

9. Chemistry Item 03-01 Thus from the choices in the previous question, only 12 g carbon, 6.02 x 10 23 oxygen atoms and 22.4 L N 2 gas are equal to one mole. On the other hand, 1 g H 2 is not equal to one mole since a mole is equivalent to a substance molar mass. The molar mass of H 2 is 2 g since there are 2 atoms of hydrogen in the formula. www.upcatreview.com

10. Chemistry Item 03-01 To make it equal to I mole, the mass should be 2 g (which is H 2 molar mass) and not just 1g thus letter A . www.upcatreview.com